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Message started by frankuitaalst on 03/28/07 at 13:19:12

Title: Asteroids
Post by frankuitaalst on 03/28/07 at 13:19:12

Asteroids are something very interesting to simulate with GS , therefore this new topic .
Hereunder a link to the asteroid 2004GU9.
http://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=2004GU9&group=all
This one has an orbit which comes close to the earth . Special about it is the revolution period which seems to be 1.001 years . This means it must be strongly under influence of the earth . Its rather big . Diameter is estimated to be 170 - 380 m
Running the sim I created an .xls file and represented the distance to earth and the evolution of the SMA as a function of time . Result hereunder ...
The SMA varies a lot and seems to have a cycle of about 70 years . The minima and maxima correspond to the closest approaches to earth . The closest approaches have a period of about 35 years .
There must be a connection between the closest approaches cycles and the SMA .
I just don't feel by intuition or by maths why the period of the SMA is just the double of the period of closest approaches ... Someone does ?

Title: Re: Asteroids
Post by Tony on 03/28/07 at 20:03:16

Your intuition is right.  They are definately related to each other.

This asteroid has a facinating orbit.  Thanks for bringing it to our attention.  I've wondered if any asteroids could exist in such orbits.  I guess they can.  I just grabbed its data and simulated it.  Appearently, it is trapped in a quasi-orbit around Earth.  This is similar to 2004AA29, which is featured on the Simulations link:  http://www.orbitsimulator.com/gravity/articles/2002aa29.html .  But unlike 2004AA29, this asteroid spends a lot more time in the quasi state.

Because of 2004GU9's eccentricity, it traces an oval around its average position in the rotating frame.  And this oval encompases the oval traced by Earth in the rotating frame.  Earth's eccentricity is less, so it traces a smaller oval, as it doesn't venture as far from its average position.

This asteroid's semi-major axis is currently slightly greater than Earth's.  This means its period is slightly greater as well.  Orbit after orbit, the trailing edge of its oval approaches Earth.  Earth's gravity pulls it on it in a retrograde direction.  This causes its orbit to shrink a little.  As its semi-major axis decreases, its period decreases as well.  Eventually, its period exactly matches that of Earth's.  Earth's gravity continues to pull, lowering the asteroid's semi-major axis and period to less than Earth's.  This causes 2004GU9's oval to reverse direction in the rotating frame, as it is now travelling around the Sun faster than Earth.  It continues heading in this direction until the new trailing edge approaches Earth.  The opposite now happens.  Earth pulls it in a prograde direction, expanding its semi-major axis and its period until its period is once again greater than Earth's, causing it to once again reverse direction in the rotating frame.

Here's my simulation.  Rotating frame is turned on, and set to Earth's period.
http://orbitsimulator.com/gravity/simulations/2004GU9.gsim

Here's an animated GIF of~70 simulated years.
http://orbitsimulator.com/gravity/images/2004gu9.GIF

I re-made your graphs to seperate them, and expand them horizontally to zoom in a bit.  Keep in mind, the period of closest approach is not 35 years.  It is 1 year.  Every year, the asteroid makes a close approach to Earth.  But each year, the close approach distance varies, from a minimum to a maximum.  This is what has a 35 year period.  The zoomed-in graph makes this a little clearer.

This graph shows you the state of the system at various points on the graph.
http://orbitsimulator.com/gravity/images/gu9e.GIF

I also Google'd it and found that Astronomy.com has a nice article on this asteroid:  http://www.astronomy.com/asy/default.aspx?c=a&id=2060

Title: Re: Asteroids
Post by frankuitaalst on 03/29/07 at 08:37:54

Looking at the picture in the moving frame I thought , "waw we discovered earths second moon ".  :)
Quite an amazing orbit !
Googling I found out that NASA already discovered this feature ..., but only 9 months ago ...
See the nice link http://science.nasa.gov/headlines/y2006/09jun_moonlets.htm.
According to NASA it has been there for at least 500 years in this orbit .
I'll try a high precision simulation run back in time and see what happened ....

Title: Re: Asteroids
Post by frankuitaalst on 03/29/07 at 13:05:12

Nasa is right ...
Asteroid 2004GU9 was in our neighbourhood for the past 500 years , but where was it before ??
I don't know ....yet
Herunder the result of the simulation "at high definition" of the ast.
The figure shows the SMA of the ast and the diastance to earth .as a function of time ( time in yrs)
It is clear that about 500 years ago , something happened . The ast was not as closely bound to earth as it is now .
The Dist to earth  goes up tu around 3.0 E11 m ie twice the SMA of earth .
Does it originate from the asteroids belt and was it captured around  1500 AC ? Probably not , as the SMA changes , but stays close to the SMA of earth , meaning that the ast was more or less in the same orbit , but not "bound" to earth at it is now....

Title: Re: Asteroids
Post by Tony on 03/29/07 at 14:20:19

After escaping, it should be in a horseshoe orbit.  Examine it in the rotating frame and see.

Title: Re: Asteroids
Post by Tony on 03/30/07 at 01:21:03

Simulating forward, I find that it leaves its semi-quasi state in the year 2605.  And it does indeed enter a horseshoe orbit after escaping.

Title: Re: Asteroids
Post by frankuitaalst on 03/30/07 at 08:38:25

Simulating forwards and backwards for in total about 4000 years it seems that the asteroid indeed comes from and goes to an horseshoe orbit . Right now it is almost at it closed binding with earth . The relationship to earth lasts for about 1000 years as can be seen in the picture herunder ...

Title: Re: Asteroids
Post by frankuitaalst on 03/31/07 at 02:54:07

Here's another interesting one ...2001GO2...
Data were taken from the nasa site hereunder .
http://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=2001GO2&group=all
Simulating forwards and backwards from 01/02/2007 on shows that the asteroid is in an horseshoe-orbit around the earth , but will become bound to earth in about 200 years , staying for about 50 years and then going into horseshoe again . Remarkable is the fact that not so long ago it was bound to earth also , after having been in a horseshoe .
There seems to be some pattern in it .
I wonder what's causing this transition from horseshoe to bound orbit . Is it simple a question of earths gravity , or is it the interaction of venus , or mars or maybe the mighty jupiter ? I think jupiter is strongly involved as due to his enormous mass the force on the asteroid exceeds the forces of the  other planets ( not considering the grav filed of the sun ) .

Title: Re: Asteroids
Post by Tony on 03/31/07 at 03:19:17

You can always delete Venus and Jupiter and try again  ;)  My guess is that they're not major influences.

But don't delete the Sun  [smiley=tongue.gif].  Trust me, it's needed or Earth and the asteroid will depart ways forever.

Title: Re: Asteroids
Post by frankuitaalst on 03/31/07 at 03:39:45


Tony wrote:
You can always delete Venus and Jupiter and try again  ;)  My guess is that they're not major influences.

But don't delete the Sun  [smiley=tongue.gif].  Trust me, it's needed or Earth and the asteroid will depart ways forever.

Just guess whats running now on my computer ? :)

Title: Re: Asteroids
Post by frankuitaalst on 03/31/07 at 08:22:19

You're right Tony , neither Jupiter nor Venus can declare the jumps between horseshoe orbit and  bound orbit ...
Herunder the screenhot .
Blue represents the real SMA of the asteroid .
The pink one is simulated forewards , but with Jupiter deleted from now on .
The yellow one is simulated backwards with Venus deleted .
Jupiter seems to have an influence on the orbit after a couple of hundred years , but does not influence the transition ...Question remains unsolved ....

Title: Re: Asteroids
Post by frankuitaalst on 03/31/07 at 10:21:46

2003YN107.... Asteroid , maybe the last one with interesting changing orbit ...
For reference Nasa has a nice site about it : http://science.nasa.gov/headlines/y2006/09jun_moonlets.htm
This small moonlet was for about 7 years our companion and left the orbit around earth last year . Since then it is in a horseshoe orbit . It will come back in about 60 years , but this time it won't stay ...
Herunder a screenshot of the simulation for 2000 years , zoomed into our lifetime .
The rest of the simulation indicates that this asteroid is not bound closely to earth but prefers its horseshoe ...

Title: Re: Asteroids
Post by frankuitaalst on 04/01/07 at 04:11:44

May Earth get a new Trojan ?
Probably not , but it could haven been ... even not on first of april

Our sister planet Venus has a real Trojan , Asteroid 2002VE68 , discoverd recently (2002) . It's not really big , but has an unusual orbit which takes it close to the orbit of mercury and earth .
Data can be taken from the site http://neo.jpl.nasa.gov/cgi-bin/db?name=2002+VE68.
Running a simulation with this data for about 2500 years the following screen shots were generated in excel :
Like other Trojans or Coorbitals the orbit seems not really stable ( see second image : variation of the SMA of the asteroid )  
The upper image makes clear that , although the asteroid is a Trojan of Venus , it spents some time closer to earth than to venus ! .  It even came inside the orbit of the moon !
The SMA tends to increase with time . That should bring it closer to earth .
I wondered how big is the influence of earth on the asteroid .
Just adding numerically (not vector)  the forces of earth and venus on the asteroid , and take the ratio Fearth/(Fvenus+Fearth), gives the yellow scattered line . It varies between 0.0.. and almost 1.
This means that Earth really has a big influence on the asteroid .
The moving average of this ratio ( red line ) makes clear that the ratio really can exceed 0.5 , meaning Earth has a stronger influence than venus .
At the end of the sim it seems that 2002 VE68 has settled itself on a ratio slightly under 0.5 .
The pictures may seem fluffy due to downscaling in order to get under the 250k limit .

Title: Re: Asteroids
Post by Mal on 04/01/07 at 10:52:28

Do you guys have gravsim render farms or something? How the heck churning out these sims so quickly?!

I have to marvel at the structure of the graphs here too, so regular!

Title: Re: Asteroids
Post by abyssoft on 04/01/07 at 11:31:35

Some of us do, currently overhauling parts of my system to try to increase performance again.  I'm Really hoping to get one of the new Quad AMD systems  ;) :P ;Dhoping Tony recompiles and converts to VB.net, and compiles a multi-processor version [smiley=vrolijk_26.gif]

Title: Re: Asteroids
Post by Mal on 04/02/07 at 00:22:08


abyssoft wrote:
Some of us do, currently overhauling parts of my system to try to increase performance again.  I'm Really hoping to get one of the new Quad AMD systems  ;) :P ;Dhoping Tony recompiles and converts to VB.net, and compiles a multi-processor version [smiley=vrolijk_26.gif]


Yeah, a program like this is crying out for multiprocessor support...  :(

Title: Re: Asteroids
Post by Tony on 04/02/07 at 01:05:38

If I owned a multi-processor machine, I'd probably be writing code for it.  (I don't think dual-core counts)

Title: Re: Asteroids
Post by abyssoft on 04/02/07 at 07:32:01

Yup dual core Does Count with out the proper multiproc code it can't fully utilize both cores.

Title: Re: Asteroids
Post by Tony on 04/06/07 at 01:18:55

http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1565.pdf
Here's an interesting link that fits well in this thread.  It makes me want to modify the rotating frame feature to include side views.

Title: Re: Asteroids
Post by frankuitaalst on 04/14/07 at 03:59:24

This might be a goodie too to simulate ...2001CK32 ... The SMA and dist to Venus indicate this is another Trojan of our sister planet . As the other asteroid 2002VE68 this one comes also in the neighbourhood of earth , so is also under influence of our planet ...The asteroid is not really small , about 1 km in diameter .
Simulation started at 01/02/2007.
Information was taken from this source http://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=2001CK32&group=all

Title: Re: Asteroids
Post by frankuitaalst on 04/14/07 at 05:57:25

Maybe this is a third Trojan of Venus ...Asteroid 2003KO2... it's about 500 meters wide and has an inclination of ca 23° .
The orbit is remarkable stable , in contrast to the other 2 asteroids above.
That s perhaps somewhat surprising as the asteroid comes in his orbit much closer to earth than to Venus , as can be seen from the picture herunder .
In the pictured timescale ( from 1/2/07 on ) the mean distance to earth was only about 20% bigger than the mean distance to venus .

Title: Re: Asteroids
Post by frankuitaalst on 04/15/07 at 13:13:37

A new Trojan for Mars ? Maybe , look at the picture below ...
The ast 1999ND43 is rather big and has a SMA which is about the SMA of Mars ( thats how I identified it ) . The asteroid has an elliptical orbit which brings it in the neighbourhood of earth , meaning our earth has an influence on it .
Out of the graph it is clear that the ast is slowly drifting away from Mars ; but also that Earth changes the SMa und thus the orbit rather regularly . Must be fun to get a rotating frame ....

Title: Re: Asteroids
Post by frankuitaalst on 04/15/07 at 13:27:42

I forgot to append a link for Mars Trojans .
http://en.wikipedia.org/wiki/5261_Eureka

Title: Re: Asteroids
Post by Tony on 04/15/07 at 15:13:14

I haven't tried your new Venus one yet, but I did try the Mars trojan.  At a time step of 16K, it does have trojan behavior.  And if you rotate the frame with the Earth's period, you can see exactly what is causing the sma jumps.  It is in an imperfect 15:8 resonance with Earth.  As one of the perihelion loops approaches Earth, the rate at which it approaches slows down, but not enough for Earth to reverse its direction.  It crosses Earth and picks up speed again.  It spends the majority of its time at the fast clip, and like a rubbernecker on the highway, it slows down every time it gets close to Earth.  So the low sma's that don't last too long on your graph represent this.

Title: Re: Asteroids
Post by Tony on 04/15/07 at 15:22:40

After running the Mars one a little longer, it may not be a trojan, but rather a horseshoe, similar to Earth's Cruithne.  But I'm running at 16K, so I don't exactly trust my conclusions.  I wish I had 10 computers  :-[ ... When I finish playing around with VE68, I'll take a closer look at the Mars asteroid.  I think I'll have to leave it running overnight to do justice to it.

Title: Re: Asteroids
Post by frankuitaalst on 04/25/07 at 09:45:40

I think 1999ND43 is in a horseshoe orbit ( whats by the way the difference between a horseshoe and a trojan ? ) .
I haven't seen it yet in a rotating frame , but analysed the orbit with Pic and Excel
Here are some schreenshots :
It looks as if the asteroid is moving just a little bit faster than Mars . ( Tast/TMars <~1) .
The distance to the planet increases with time , meaning  it is getting further .
When I saw this I thought : nopes , just a coorbital .
After calculating the angle between them however it seems that the angle "pendles" between max and min , which indicates the asteroid may have an horseshoe .
I think that the asteroid must now be "before" Mars as the angle increases and as the Ast is moving faster .
It may look that after a period of time the Ast may leave the horseshoe , as the max angle increases...
There is some literature about Mars Trojans , about six or even more are known , but I didn't find this one listed ...

Title: Re: Asteroids
Post by frankuitaalst on 05/09/07 at 14:34:34

This asteroid 2007AG ,discovered this year, might  have an interesting orbit as it has almost the same period as venus buth also crosses mercury and earth .
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2007+AG&orb=1

Title: Re: Asteroids
Post by frankuitaalst on 05/09/07 at 22:51:15

An example af an asteroid squeezed between three worlds .
It has an elevated orbit , almost co-orbital with Venus which brings him close to earth and even much closer to mercury . The asteroid is definitivly influenced by both other planets .This becomes clear from the pictures below . Around the year 800 (+2007) it makes some close passes to mercury , changing its orbit ( speeding it up ) . Between the year 1000-1100 some close flybys with earth  slow it down again . In the meantime the asteroid seems to orbit an horseshoe around venus .

Title: Re: Asteroids
Post by Tony on 05/10/07 at 00:33:03

Those little 100 year cycles in the beginning are from an 18:11 mean-motion resonance with Earth.  Here's 300 years of animation in a rotating frame set to Earth's period.  Based on your graph, it looks like it breaks the resonance after about 800 years.  I'm starting to get the sense that these temporary mean-motion resonances protect Earth from getting hit more often.
http://orbitsimulator.com/gravity/images/2007ag.GIF

Title: Re: Asteroids
Post by frankuitaalst on 05/12/07 at 13:14:59

I wonder If there is also a resonance to venus after 1000 years ?

Title: Re: Asteroids
Post by frankuitaalst on 05/13/07 at 12:32:26

Asteroid 2006FV35 , not really big , but size over 100 meters has an orbit with period 365 days . Seems to  be a stable one . It is not mentionned (yet ) as a horse -shoe asteroid to earth as far as I know . Herunder the graph over the next 600 years .

Title: Re: Asteroids
Post by frankuitaalst on 05/30/07 at 12:50:40

Simulating 2006FV35 in a rotating frame aroud Earth shows that the asteroid indeed is in an Horseshoe orbit around Earth . In this frame Earth is the little green line at the left . As Earth has a slightly eccentric orbit around the sun , Earth is not represented as a dot but as a line as the distance from the sun changes . Frames were taken once a year for about 25 years.

Title: Re: Asteroids
Post by Tony on 05/30/07 at 18:07:07


frankuitaalst wrote:
Simulating 2006FV35 in a rotating frame around Earth shows that the asteroid indeed is in an Horseshoe orbit around Earth...

Your animation doesn't span enough time to conclude that it in a horseshoe orbit.

** edit **
I tried simulating it.  It is not horseshoe, it is quasi-orbit, which is more impressive.  And it seems to be stable for long periods of time.  I think I'll let this one run for a while.


frankuitaalst wrote:
...In this frame Earth is the little green line at the left . As Earth has a slightly eccentric orbit around the sun , Earth is not represented as a dot but as a line as the distance from the sun changes...


That's neat that you've got the rotating frame working.  When I do rotating frames, I get ovals instead of lines.  In your case you are probably locking Earth's longitude, which means that your frame is not rotating with a consistent speed.  It's an interesting way to do it though.

The oval in my simulations is caused because when the Earth is closer to the Sun, it also travels faster, so it gets ahead of its average position.  Then when it is farther from the Sun, it travels slower, so it gets behind its average position.

Title: Re: Asteroids
Post by frankuitaalst on 05/30/07 at 22:34:16

yes , i adapt the rotating frame speed at each iteration , so that the planet stays at a fixed "angle" . Needed some time to figure out how to do , but the combination of the scalar (dot) product and the vector product generates the cos and the sin, which are necessary for the rotation so this works  :).
Working this way it is also possible to calculate the momentaneous angular speed . Is quite interesting also .

I ran this sim in a normal frame (see above) for about 600 years and got the impression it might be interesting . I don't find yet any reference in the Inet for this unusual orbit .

This ast is really interesting . It is in a quasi orbit around earth , getting inside the orbit of venus (in rotating frame ) and is oscullating (kissing) the orbit of Mars .

Title: Re: Asteroids
Post by Tony on 05/30/07 at 23:38:26

Looks like someone beat you to it:
http://www.astro.queensu.ca/KIK/brasser.txt

Title: Re: Asteroids
Post by frankuitaalst on 05/31/07 at 08:54:41

Nevertheless , here's an animation for the coming 190 years for the asteroid 2006FV35 in rotating frame aroud Earth.
The period of the oscillation is around 160 years . Please note however that the frames are not equidistant in time.

Title: Re: Asteroids
Post by frankuitaalst on 06/01/07 at 12:19:22

Another interesting Asteroid is the 2005UH6 one .
It has a high eccentric orbit bringing it into the orbit of Mercury , crossing Venus and Earth and into the orbit of Mars .
It's period is only little larger than Earths . So this must be a candidate for a horseshoe orbit around earth.
Along its orbit the asteroid passes regularly it a distance of only 0.02 AU from the four planets .
For some reason this rather big one (0.6-1.3km ) manages to avoid all of the planets .
Heres a simulation in a rotating frame around Earth .
The sim starts in 2007 and ends about 300 years later .
It's amazing to see how the asteroid approaches Earth ( the little green line at the left ) continiously and then reverses ...

Title: Re: Asteroids
Post by frankuitaalst on 06/01/07 at 13:00:13

2000WN10 has a high inclination of about 23°. Its period is a little bit larger than earth . It was discovered in 2000 when it was at a distance of more than 0.2 AU from Earth .
Size is estimated between 270-610m .
Its motion in a rotating frame is not so exciting as the previous . Coming closer to Earth in the next few years it "passes" Earth as can be seen , contrary to the 2005UH6 ast which seems to be repelled . Maybe the distance to Earth remains to big (0.1 AU) so that it is not accelerated enough to be "repelled" .
I accelerated the frames after the close approach to earth in order to save some disk space.

Title: Re: Asteroids
Post by frankuitaalst on 06/01/07 at 22:37:01

2003YN107 was mentionned before in this tread . Its a small asteroid , not much bigger than a church or house here on earth . It was discovered in 2003 when it came close to earth and has a period corresponding to ours.
Its mean feature is that it now seems to orbit a kind of pearl orbit as can be seen in the following rotating frame .  
It has another remarkable feature around 2003 when it came close . I'll try to represent this later .

Title: Re: Asteroids
Post by frankuitaalst on 06/01/07 at 23:08:43

2003YN107 became around 2003 almost a moon of earth as can be seen in the rotating frame herunder .
The gif starts in 2007 and spans ca. 10 years back in time . The gif represents the orbit of 2003YN107 in a rotating frame around earth but also centered on earth .
So Earth is right in the middle .
The green orbit represents the orbit of our present moon .
As can be seen (one should think in reversed mode ) the ast approaches , then makes a couple of elliptical orbits around earth and  leaves ....

This orbit can be compared in some ways with the orbit of 2002AA29 which can be downloaded in the menu simulations

Title: Re: Asteroids
Post by Tony on 06/02/07 at 01:17:06

I was playing around with 2003 YN107 as well  ;)  It's orbit is actually very similar to the orbit of the Spitzer Space Telescope.  See my link in the 'Simulations' page of the main web site.

Here's some other interesting stuff I found.  I want to do long-term simulations on most of these to confirm what the quick simulations are hinting at:

Earth : 2007 FA are in a 7:5 resonance
seems strong.  doesn't cross Venus
Crosses Mars, so Mars may eventually break its resonance
Only the counterclockwise edge has repelling power.

Earth : 2007 AM are in a 5:7 resonance
both edges have repelling power, giving the appearance of quasi, except that quasi is a term applied to 1:1 asteroids.
This lasts for a little more than 3000 years from present before an encounter with an unknown planet breaks if from this quasi-quasi state.


Earth : 2006 FV35 are in a 1:1 resonance.  Frankuitaalst's find.  It is in a long-lasting quasi orbit.

Earth : 1998 KG3 are in a 5:4 resonance.  Very strong resonance.  Lasts at least 20,000 years.  It doesn't cross Mars or Venus, so there's nothing to break it of its resonance.  Maybe it lasts forever.

Earth : 2001 GO2 are in a 1:1 resonance.  Horseshoe at the moment, was quasi in the 1800s.  Will be quasi again in about 200 years.  Seems to jump between quasi and horseshoe frequently.  No intersection with Mars or Venus.  It's all Earth's.

2003 WP 25, almost 1:1, but no resonance.  It does not intersect Mars or Venus.  Perhaps it will enter resonance when its nodes drift.

2003 YN107, horseshoe orbit, very similar to Spitzer Space Telescope.

2004 GU9, quasi orbit.  No intersection with Mars or Venus

2004 YG1, almost 1:1, but no resonance.  It does not intersect Mars or Venus.  Perhaps it will enter resonance when its nodes drift.

2005 CN61, almost 1:1, but no resonance. Compression can be seen as it passes Earth.  It does not intersect Mars or Venus.  Perhaps it will enter resonance when its nodes drift.

2005 QQ87, very slow drift.  Can not crest L1 at ts=1024,  possible L4 Trojan.  Odd orbit.  Not quite like an L4 as its advancing edge passes Earth.  Its trailing edge repels it.  So although it "orbits" the L4 point, its advancing edge drifts past Earth and L1.

2005 TC51, close to 1:1, but no resonance.  Its clockwise edge causes compression.  Might enter resonance as its nodes drift.

2005 UH6, very slow drift.  counter clockwise edge has repulsion far from Earth, even though its nodes are not near Earth.  Can't crest L3.  This thing is an L5 trojan

2006 FV35, Big looping quasi orbit.  Never gets very close to Earth.

2006 YX2, seems to have a 28:17 Venus resonance (Venus : 2006 YX2).  Doesn't pay much attention to Earth.

2007 DD,  doesn't cross Mars or Venus, almost 1:1 with Earth, but no resonance.

2007 FN3, possible Mercury resonance.

2007 JB21,  doesn't cross Mars or Venus, almost 1:1 with Earth, but no resonance.

138175 Horseshoe with 1 repelling edge. Clockwise edge has repulsion power.  This asteroid can reverse course mid-stream due to Venus.  seems at first to have a Venus resonance, but it is quickly broken

Izhdubar, huge 63 degree inclination.  Kozai must mess with this thing. ~130 thousand year Kozai period from Jupiter.

Yorp, sometimes it reverses, sometimes it doesnt.  Kidney-bean

85770, Horseshoe with 1 repelling side

Title: Re: Asteroids
Post by frankuitaalst on 06/02/07 at 01:36:27

waw impressive  :o :). How did you find out this all ? Have 1000 computers ?
Maybe I can simulate some of them if we join forces .
Other idea can be putting them all together in one file , let it run , output the files and then from this file generating the disired screens . May have big advantages on total CPU  :)

Title: Re: Asteroids
Post by frankuitaalst on 06/03/07 at 14:45:51

The orbit of 2003YN107 doesn't seem to be stable for long .
In a simulation starting from now for 600 years the asteroid chooses another orbit after ca. 500 years as it passes close to earth . It seems to jump out of its orbit .
Remark in this rotating frame ( Earth is the "line" at 10 'o clock ) that the asteroid sometimes is repelled from earth , sometimes not .
This gif consists of 60 frames , each covering 10 years . The individual dots have a time lap of ca. 10 days.

Title: Re: Asteroids
Post by frankuitaalst on 06/18/07 at 23:00:39

JPL states that there are now 871 potentially hazardous asteroids known coming close to Earth .
http://neo.jpl.nasa.gov/ca/.

The site also gives a list of the 10 latest  close approaches to the earth. Figure hereunder.
Remarkable is the fact that in this list of 10 bodies only 1 of them was known before this year , 9 of them were discovered this year .  This is due to the fact that
-most of the bodies are discovered when they come close
-the increasing efforts and capabilities of detecting asteroids .
Nevertheless its a little bit scaring that there are a lot of potential impactors which are detected only some days/weeks/months before their close approach

Title: Re: Asteroids
Post by frankuitaalst on 08/10/07 at 09:08:22

Asteroid 1998WZ6 :
How pictures as the following can be misleading .....
The following sim shows the orbit of the (relatively ) large asteroid 1998WZ6.
Screenshots cover a period of 20 years . The asteroid is shown as the green line .
Earth is the planet at the left .
The screenshot shows the asteroids path in a rotating frame around earth , viewed edge-on .
Screen size is 5 AU .
Difficult to follow ...amazing orbit ...
The next post will clarify something ...

Title: Re: Asteroids
Post by frankuitaalst on 08/10/07 at 09:24:00

The following picture may clarify the odd orbit shown above .
In this frame the orbit is shown from "above " .
Earth is the little dot at 11 'o clock in this rotating frame around earth .
In this view it is clear that the asteroid is in resonance to earth .
In fact the resonance is exactly 1:1.75 , meaning the asteroid takes his position again after 8 years .
( look how beautiful the orbit matches the previous orbit after 8 years) .
The odd orbit above is created while the asteroid 1998WZ6 has a rather big inclination of 24° and a rather big excentricity of 0.4 .

Title: Re: Asteroids
Post by frankuitaalst on 09/05/07 at 11:29:35

...Gravity assist procedure for Asteroids ....
The recently discovered asteroid 2007RF1 ( not very much more than a big rock ) must have made a close flyby at Venus on July 14th 1970 (any French compatriots here ?) and gained enough energy to augment its SMA.
Heres a simulation of the path of the asteroid ( data taken from NEA - site ) , simulation goes back in time .
First part shows the path ( in green ) from above . At a given moment 2007RJ1 meets Venus at about 8 'o clock and changes its orbit outwards .
The second part shows the path in rotating frame around Venus . Venus is here the pink dot at 3 o clock .
This sim starts as the asteroid approaches Venus from the outside and comes really really close .
According to the Ephemerides it must have been 0.0008 AU away from Venus.

Title: Re: Asteroids
Post by frankuitaalst on 09/11/07 at 05:10:06

Three  times 10 years in the life of an asteroid or how pictures can be misleading ...
In the following screenshots the orbit of the asteroid 2003FY6 is shown in 3 rotating frames , first around Earth , then Venus and last around Mercury . The first picture shows the orbit as can be seen in the jpl NEA site .
The three frames were generated as the asteroid crosses the orbit of the three planets mentioned above.
It's remarkable how in each case the orbit has a different aspect .

Title: Re: Asteroids
Post by frankuitaalst on 09/12/07 at 10:44:54

Influence of Jupiter on asteroids :
The following sim gives an idea about the influence of Jupiter on the recently discovered asteroid 2007RR9.
The ast is rather big ( mag about 20 ) . It' not really a tread to Earth according to the calculations available now .
In the animation herunder you'll see 3 simulations pasted together :
first : the orbit for the next 100 years
second : the orbit in the past 50 years
third : the orbit in a rotating frame to Jupiter as simulated for about 80 years (one frame per year) .
The initial frames show the data of the asteroid from the NEA site and the NEODSYS site .
The asteroid came close to Jupiter in 1982 and will be close again in 2042 an 2054 .
It's interesting how Jupiter alters the asteroids path :
Now the asteroid crosses the orbit of the Earth . Before the pass in 1982 it was outside the Earth's orbit .
After the next encounter with Jupiter it will again not cross the orbit of Earth anymore ( but will stay "outside").
The results are preliminary as they are calculated on merely 2 days of observation .

Title: Re: Asteroids
Post by frankuitaalst on 09/19/07 at 13:44:11

Very recently a very large asteroid was detected as 2007SJ . Its estimated diameter is about 2 km
On 2017/01/24.91250 57777.9  it will come as close as 0.0213234 AU from Earth (data from Neodsys).
Unlike other asteroids this one was detected when it was still very far from earth ie. more than 0.1 AU ( most of them are detected when they will come close within a few days , or even have passed Earth ) .
Hereunder a screenshot of its close pass to Earth in 2017.
The red circle represents the orbit of the moon .

Title: Re: Asteroids
Post by frankuitaalst on 09/20/07 at 10:52:13

Correction to the post above ....
The asteroid has been observed for one day more and the tread to Earth seems to be gone according to the new ephemerides .
Instead of coming closer the next years ,it is now moving away from earth .
Curiuos about his past I created the following rotating frame back in time ...for 50 years .
The asteroid starts at 2 'o clock and moves towards Earth , but after 30 years it seemed to "hold" .
I never saw this behaviour before .
This asteroid is yet second on the hazard scale of NEA. First is Apophis .
Maybe tomorrow the situation may have changed again after additional observations .

Title: Re: Asteroids
Post by Tony on 09/20/07 at 12:52:29

Not only should it hold, but it should reverse direction.  This looks like a 3:1 resonance with Earth.  It's very similar to Pluto's 3:2 resonance with Neptune described here:  http://www.orbitsimulator.com/gravity/articles/pluto.html

Title: Re: Asteroids
Post by frankuitaalst on 09/20/07 at 13:05:23

You're right : 3.01 years orbit according to NEA . In the sim the ast was receding , but rather hesitating ...

Title: Re: Asteroids
Post by Tony on 09/20/07 at 14:59:18


frankuitaalst wrote:
You're right : 3.01 years orbit according to NEA . In the sim the ast was receding , but rather hesitating ...

3.01 years now, 2.99 years after the reversal, 3.01 after the next reversal...  leading to a time-averaged value of exactly 3.  This is what is meant by mean-motion resonance.  Pluto's not exactly 3:2 with Neptune at any given instance either.  But over long periods of time it averages to exactly 3:2

Title: Re: Asteroids
Post by frankuitaalst on 09/20/07 at 22:42:19

Yeah . The movement is rather exceptional in this case : where the ast moves close in the past and reverses , in the future it moves away from Earth and comes very close after 200 years ( at the opposite site ) , then reverses . But when coming close after 400 years it gains speed and overshoots and crosses the Earth .
I made some screenshots .

Title: Re: Asteroids
Post by Tony on 09/20/07 at 23:08:05

That's what I found too.  So this one is not in a stable resonance.  But after they better refine the orbit, that may change.  The speed at which it progresses is not constant.  I deleted Jupiter from the simulation to verify that Jupiter was the cause of this.  It was.

Here's the simulation for anyone who wants to try it.  It is in a rotating frame with Earth's period:
http://orbitsimulator.com/gravity/simulations/2007SJ.gsim

Title: Re: Asteroids
Post by frankuitaalst on 09/22/07 at 07:38:34

This asteroid 2007SJ may be one to watch ... :-?, as it is very big .
It was tracked for 2 days more now ( total 4 days) . Its period is now calculated to be 2.88 years , giving it a different orbit . Here's a screenshot after more than 10 years in rotating frame to earth . Seems it is heading in our direction ...
The current rating in the Palermo scale is bigger than that of Apophis.

Title: Re: Asteroids
Post by frankuitaalst on 09/22/07 at 12:10:00

As the position and velocity of the asteroid is still not very certain and to get any feeling what this uncertainty implies I simulated the orbit of 2007SJ together with 6 close orbits , each at a distance of 300.000 km of the asteroid in the x+-,y+- and z+-  direction.
This corresponds roughly  with the distance Earth- Moon . This also means a deviation of its current position of 10-4 ! .
I think the uncertainty now is much bigger .
The sim hereunder covers almost 40 years from now .
It is clear that with time the asteroids spread out , but also that the next encounter with earth is closer than the first . I think this asteroid will get into the papers sometime ...

Title: Re: Asteroids
Post by frankuitaalst on 09/23/07 at 06:12:40

New observations are available for 2007SJ ; one day of observation was added ; it's period is now estimated to be 2.87 years.
Herunder is a simulation in which two orbits are shown : the orbit as predicted yesterday in drak green and the orbit with the parameters of today in light green. Both bodies were given "zero" mass .
The asteroid comes much more closer to earth in 2014 than estimated before.
According to the Neodys site it will not come closer than  0.0644834 AU. on 2014/02/19.95404

Title: Re: Asteroids
Post by frankuitaalst on 09/24/07 at 08:55:36

One more day of observation for 2007SJ still keeps it to be the most serious threat .
On 24/09/07 the period was computed to be 2.85 years .
Hereunder the orbit of the asteroid ( in light green) .
The dark green orbit is the orbit as prognosed two days ago .

Title: Re: Asteroids
Post by frankuitaalst on 09/24/07 at 09:20:22

One of the most "tortured" asteroids is surely asteroid 2002GJ8.
This one has a very eccentric orbit and  comes very close to Jupiter . This results in a drastic change of  its orbit as can be seen in the following picture .
The sim spans 150 years . The three first frames are back in time (50 years ) . The rest is straight forward .

Title: Re: Asteroids
Post by frankuitaalst on 09/30/07 at 04:58:51

Asteroid 2007SJ : the threat seems to be gone .  :)
After some more days ob observation the error on the measurements seems to be reduced , giving the asteroid a minimum diestance to earth of about 0.04 AU . Period remains the same as before .
Heres the orbit in a rotating frame : the new orbit appears very close to the last one . The orbit estimated on 23/09 is still indicated as the dark green orbit .

Title: Re: Asteroids
Post by frankuitaalst on 10/05/07 at 12:33:29

A "lost" asteroid was found again recently .
The asteroid 6344-PL was discovered in 1960 and was lost for several years .
Recently another asteroid was discovered : 2007RR9 . I stored its data on 12/09/07.

According to an article in the BAD-forum the asteroid 2007RR9 is now considered as the lost asteroid 6344-PL . This matching was done recently . Good job .  :)
As I stored the data of 2007RR9 on 12/09/2007 and yet have the data of 6334-PL it's easy to compare the orbits . The light green orbit represents the orbit of 6344PL . The dark one the otbit of 2007RR9.
I notced that JPL has deleted the previous data of 2007RR9.
In the figure I marked the situation on 12/09/07 .

Title: Re: Asteroids
Post by frankuitaalst on 10/15/07 at 07:09:34

Another Asteroid is on its way to Earth ...
2007SJ doesn't seem to be a threat anymore but its brother 2007TU24 , recently discovered ,takes over .
According to Neodys the asteroid will make a close pass to Earth on 29/01/2008 within 0.0037 AU , maybe as close as 0.00186 AU .
Hereunder is a picture : shown is the Earth at center with the orbit of the moon .
Light green is the path of the asteroid as known now .
Dark green is the path as it was known yesterday .

Title: Re: Asteroids
Post by Tony on 10/15/07 at 09:36:36

Thanks for keeping us safe, Frank  ;D

I made a .gsim file for anyone who wants to play with this asteroid.  It misses Earth by less than 600,000 km.  It will be interesting to follow it as its orbit is refined.

http://www.orbitsimulator.com/gravity/simulations/2007TU24.gsim

Title: Re: Asteroids
Post by frankuitaalst on 10/15/07 at 12:08:54

I'll do all of my best Tony  ;D . We have to watch this one as the threat according to Palermo is even bigger than that of Apophis ! It's not small either : more than 200 m in diameter . Also the encounter is only 3 months from now ...
BTW : I'm very interested in simulating negative masses but it seems GravSim doesn't allow this .
Any idea why ?

Title: Re: Asteroids
Post by Tony on 10/15/07 at 14:15:24

It should allow it.  I never put a negative filter in the code.  I just tried setting the Sun's mass to its negative value.  The planets all scrammed.

Title: Re: Asteroids
Post by frankuitaalst on 10/15/07 at 14:25:15

Well I guessed it should work also . Thats funny ... I tried to set one planet to negative and it just behaved as normal .  :-/
Reason I want to do this is the following : suppose you have a bunch of masses ( a cloud ) . One part of the cloud is positve , the other negative . I guess we would obtain 2 distinct systems : one positive , one negative . Correct ?  Or maybe all is ejected . I'm anxious to try it .
You're right : setting the Sun to negative mass throws the planets out . Thats fine .
However changing an individual mass to negative doesn't have an effect .  :-/

Title: Re: Asteroids
Post by Tony on 10/15/07 at 21:42:35


frankuitaalst wrote:
However changing an individual mass to negative doesn't have an effect .  :-/

The Sun pulls hard, the planet pushes slightly.  The vectors add to a vector pointed to the Sun at least 99% as strong as if both the planet and Sun pulled.  That's the advantage of being a star.  You overwhelm everything else.

Try making an object orbit the anti-mass planet, and you will see that all is not well.

Title: Re: Asteroids
Post by frankuitaalst on 10/16/07 at 07:56:09

There are days one can feel himself really stupid  :(. yesterday was such a day . Of course ...
Take : m.a= GM.m/r˛ , give the body a negative mass => a= GM/r˛ , doesn't matter .
Give the sun a negative mass : => a= -GM/r˛ , result :body is repelled .

In the meantime 2007TU24 has another observation. It comes closer than yesterday .
In annex the view from aside . In the view from above the change towards earth is much bigger .

Title: Re: Asteroids
Post by frankuitaalst on 10/19/07 at 09:55:39

The asteroid 2007TU24 is now demoted in threat , leaving the honours to Apophis again , as new observations are available .
Herunder the path of the asteroid close to Erath at end of januari 2008. It will not come closer than 0.0375AU . The parallel path shown are previous observations .

Title: Re: Asteroids
Post by frankuitaalst on 10/28/07 at 00:49:48

Recently discovered : the 2007UT3 asteroid .
It has a near 2:3 resonance to earth as can be seen herunder . Moreover it also is a near Venus and Mercury asteroid .

Title: Re: Asteroids
Post by frankuitaalst on 10/28/07 at 04:39:32

According to the latest estimations 2007TU24 will come as close as 1.4 Moon Distance to Earth on Jan 29th 2008.  Due to the close encounter the asteroids parameters are changed considerably as the next figure shows .
The asteroid gets into a wider orbit , is gaining eccentricity and comes closer to the eccliptic plane as a result of Earhs influence .  
Things may change a little as new observations become available after he full moon .

Title: Re: Asteroids
Post by frankuitaalst on 10/28/07 at 05:28:25

The serious threat from 2007SJ seems definitively gone since the last observations on 25/10/07.
The animation herunder gives the path of the large asteroids last three observations ( for 25/10, 12/10 and 30/09 ) . Light green is the last observations prediction .
The animation shows the path from above and from aside , in both cases in rotatiig frame to Earth .  

From the NeoDys Site the data for closest approach to Earth.
  EARTH  1954/01/02.71495
  EARTH  1974/02/02.52411
  EARTH  1994/01/22.55848
  EARTH  2014/01/21.87239
  EARTH  2034/02/25.72364
Remarkable is the period of almost exactly 20 years between 2 close approaches .

Title: Re: Asteroids
Post by frankuitaalst on 11/01/07 at 07:32:31

This asteroid should be in the Kozai posts ...
Asteroid 2001AU43 is the one with the highest known inclination of all Near Earth asteroids .
It is as highly as 72° degrees inclined to the ecliptic plane , making it an example for the Kozai mechanism.
The picture hereunder is the result of a simulation for 450 years , showing the evolution of eccentricity and inclination .
The asteroid still gains inclination .
According to Kozai the function cosi*sqrt(1-e^2) should be constant . The lower picture gives the evolution of this value ( shows to be more or less constant ) .
I was able to find a recent picture of this asteroid taken by the Hubble Space Telescope  , which is pasted in the background :o.

Title: Re: Asteroids
Post by frankuitaalst on 11/01/07 at 09:28:00

Last night on halloweens eve a small asteroid flew by at a distance of 0.6 Moon Distances .
Hereunder an animated gif of the path of 2007US51 (discovered the night before) .
The picture shows the path of the asteroid as seen from above and from aside , first centered on Earth and then centered on the moon.

Title: Re: Asteroids
Post by frankuitaalst on 11/02/07 at 06:08:39

Integrating the orbit of the high eccentricity asteroid 2001AU43 over 15000 years gives the following picture.
In order to speed up the simulation all planets were deleted except Jupiter and Saturn.
The orbits of them are also visible on this side-on vieuw.
It may be clear that this asteroid is the victim of the Kozai mechanism...

Title: Re: Asteroids
Post by frankuitaalst on 11/02/07 at 09:58:34

The Kozai mechanism for above asteroid is very clear in the picture herunder .
Although eccentricity and inclination vary a lot , the SMA is hardly influenced .
Timescale is almost 50000 years.

Title: Re: Asteroids
Post by Tony on 11/02/07 at 22:10:47

Thanks for the asteroid updates.  2001AU43 is facinating.  Nice graph!

Title: Re: Asteroids
Post by frankuitaalst on 11/11/07 at 01:50:25

Recently a very large asteroid was detected : 2007VA85 , measuring 3.300 meters in diameter . Such discoveries are very rare .
The asteroid has an inclination of about 132 degrees , meaning it is rotating retrograde to the sun .
Its path , strongly elongated, brings it beyond Jupiters orbit and inside Earths orbit . The period is about 8 years . I think this is the reason why it wasn't detected sooner . According to the data available now it will never come closer to Earth than 0.15 AU. At this moment it moves away from Earth .
Hereunder is the result of the simulation of the asteroid for a period of more than 100 years , showing Jupiters influence on the orbital parameters .

Title: Re: Asteroids
Post by Tony on 11/11/07 at 15:21:55

2007 VA85 is a very interesting asteroid.  It seems to be in a 3:2 resonance with Jupiter.  I'll post details later.

Title: Re: Asteroids
Post by Tony on 11/12/07 at 00:16:31

It's usually in 3:2 resonance with Jupiter, but sometimes it hiccups as seen from its ~5th to 7th cycle on the graph.  The animation captures the hiccup.  I'm guessing that precession of the nodes is the cause of it skiping a few librations from time to time.
http://orbitsimulator.com/gravity/images/VA85a.GIF
http://orbitsimulator.com/gravity/images/2007VA.GIF

Title: Re: Asteroids
Post by frankuitaalst on 11/12/07 at 09:42:47

Interesting how the asteroid skips from time to time .  
herunder is an animated gif of the same asteroid representing almost 2 cycles .

Title: Re: Asteroids
Post by frankuitaalst on 11/18/07 at 07:30:23

The highest impact possibilty now , apart from Apophis , is given to the asteroid 2007VK184.
It's size is 140 meter and it's expected to come as close as 0.004 AU to Earth in the year 2032 , thus a couple of years later than Apophis .
Herunder is an animated gif of the orbit in rotating frame of the asteroid . The orbit is shown in light green. The expected orbit from earlier observations are shown in darker green.
The latest frames shown the approach of 2007VK184 to Earth ( xy -frame) and the current data from the Neodys site .

Title: Re: Asteroids
Post by frankuitaalst on 11/20/07 at 10:20:29

As more observations become available the odds for a close approach to Earth go up and down for the asteroid 2007VK184.
Herunder is a simulation of the path of 2007VK184 showing the predictions for the latest 4 observations ( 19/11...16/11) . The light green orbit is the latest one .
The first image shows the orbits from above , the rest of the frames show the asteroid in rotating frame to Earth .
It's nice to see how the orbits are diverging alot altough the orbits are indistinguishable in the first frame !

Title: Re: Asteroids
Post by shellandtube on 11/20/07 at 11:00:04

Just goes to show how a slight error can become massive over time. Which begs the question to what limit of accuracy can they determine the orbital elements and over the course of the next few orbits how big an error in position does that introduce? To that end how can we ever be really sure these asteroids arent a threat in either the near future or distant future?

Title: Re: Asteroids
Post by frankuitaalst on 11/20/07 at 12:27:53

Good question what's the accurancy .
In general the prediction becomes more accurate as more observations become available. The theory of prediction is very nice . I think the Near Earth asteroids site gives a good description of how it's done . Basically it is done by reducing the area of a cone in which the asteroid is observed the first time.

Title: Re: Asteroids
Post by shellandtube on 11/20/07 at 13:15:44

I got to thinking about it, perhaps too much but thats just me and the way my mind works. In order to know where something is going to be in the future (time T) we need to know where it is now (time t) and all the forces acting on the body in the time interval t to T. We can't know this as its the future and so we have to guesstimate it. First we have need to know everything about the object itself (position, velocity, dimensions, mass and its distibution, rotation, albedo and probably more) and the same for every object it is going to encounter along the way. That takes care of gravity but what about solar pressure CME's and the Poynting-Robertson effect? Are they significant or over what timescale are they significant? How accurately can we predict any of these? More and more questions seemingly without meaningful answers. Then back to the original question, over the timescale in question how much do these errors compound? The only way to know is to make your best guesstimate and then see at time T how close you were. But by that time it could be too late! Like I said probably thinking about it too much but there you go some food for thought so to speak.

Title: Re: Asteroids
Post by frankuitaalst on 11/20/07 at 14:18:53

you are right in your guess. As far as I have understood the orbit of the body is first calculated after a few observations in relation to the sun , giving it the anomaly , SMA , eccentricity ,inclination , apogee ....
Also the error on this parameters is calculated due to the observational errors . Having this parameters the orbit is then recalculated by the perturbation theory in which the influence of the bigger objects in our solar system is taken into account . Neodys also takes into account the minor planets as Ceres , Pallas aso.
I don't think the influence of solar pressure or Poynting is taken into account for normal asteroids ( Apophis fi. may be an exception ) .
I guess ( but this is a guess ) that in case of close encounters with a mean body at a certain time , Neodys also integrates the motion by some algorithm analogue as the one used over here in order to improve the accurancy which cannot be obtained by the perturbation theory.

Title: Re: Asteroids
Post by Tony on 11/20/07 at 15:17:52

You're going to love these links.  This is Jon Giorgini's paper on predicting the Earth encounters of Apophis.
http://neo.jpl.nasa.gov/apophis/Apophis_CORRECTED_PREPRINT.pdf
In the paper he discusses the difficulties in predicting the circumstances of Apophis' 2036 encounter with Earth.  Factors include:

Perturbations from other asteroids that can shift its position by several Earth Radii by 2036.
The Yarkovsky effect, which we can't predict without knowing the details of its rotation and albedo, can have an effect of several Earth Radii
We don't know precisely where the planets are.  Uncertainties in the positions of the planets themselves can cause an effect of several Earth Radii.

If you don't want to read the whole paper, here's a short article that summarizes the paper:
http://neo.jpl.nasa.gov/apophis/

If anyone is interested, I can make some new Apophis simulations, one with additional asteroids, and one without, so you can compare the difference yourself.

Title: Re: Asteroids
Post by shellandtube on 11/20/07 at 19:04:27

The oracle has spoken.
Cheers tony i think that covers alot of my questions. I read the article understanding alot but not all of it. just goes to show the errors can be huge, a deviation of 1.2km in 2029 can grow to 28600km by 2036 (if i read it right). I never realised how the errors in what we know about about the planets could be so significant, from the table on page 9 it suggests this could be one of the major sources of error.
Very interesting. Cheers again.

PS. I would definately be interested in any simulations.

Title: Re: Asteroids
Post by Tony on 11/20/07 at 23:08:02

Here is a simulation containing Apophis and the 32 asteroids mentioned in Giorgini, et al.
http://orbitsimulator.com/gravity/simulations/apophis2007.gsim

You can run the simulation and record Apophis' closest distance to Earth on April 13, 2036, then run it again, this time deleting all the extra asteroids, and again recording its closest distance on April 13, 2036.  This should give you a clue about how these asteroids contribute to Apophis' trajectory.

But if you do this, you must use a slow time step.  I recommend 1 second.  This will take a long time to do.  You'll have to leave the simulation running overnight, and perhaps a few hours more depending on your computer's speed.  It should run a lot faster when you delete the extra asteroids.

I'd suggest you use either Auto Save from the file menu, or Save from Autopilot on perhaps April 12, 2036 to make sure you capture the simulation just prior to Earth passage.

I have not tried it yet.  Good luck :)

Title: Re: Asteroids
Post by frankuitaalst on 12/08/07 at 03:17:11

The recently NEA Asteroid 2007XK11 seems to be in a beautiful near resonance to Jupiter .
Here's an animaton of the simulation covering 78 years .
The orbit may change as more observations become available .

Title: Re: Asteroids
Post by APODman on 12/21/07 at 04:41:34

Hey dudes !

Maybe this asteroid deserve a simulation !


Quote:
Scientists say there is now a 1 in 75 chance the huge chunk of rock could slam into the red planet next month.

They had initially placed odds of a direct hit at 1 in 350.

"These odds are extremely unusual," said Steve Chesley, an astronomer with the Near Earth Object Programme at NASA's Jet Propulsion Laboratory.

"We frequently work with really long odds when we track threatening asteroids."

If a collision does take place, the explosion that follows could be like the famous 1908 Tunguska incident.

That blast, in central Siberia, wiped out 60 million trees and unleashed the energy equivalent to a 15-megaton nuclear bomb.

The new asteroid, known as 2007 WD5, was discovered last month and is similar in size to the Tunguska object.


more in :
- http://www.space.com/scienceastronomy/071220-asteroid-mars.html


The orbital elements for 2007 WD5 ( litte precise, need more observations ):

Epoch: 2007 11 20
Peri:  311.7
Node: 67.6
M: 2.1
e: 0.611
i: 2.3
a: 2.580
EMoid: 0.02930

font: http://cfa-www.harvard.edu/iau/lists/Amors.html



[ ]´s

Title: Re: Asteroids
Post by Tony on 12/21/07 at 10:06:41

Thanks for the heads-up on that asteroid.  If the current estimate holds, 2007 WD5 should miss Mars by less than 50,000 km on January 30, 2008 at 9:11 in the morning UT.  But Mars and its two moons, Phobos and Deimos are well within the error bars of this estimate and may be struck.  It will be interesting to follow the updated predictions and see if the odds of impact improve.

It would be very good for science if this thing did strike Mars.  With several orbiting spacecraft, we'd get some good data from below Mars' surface if it makes a crater.  With Mars' thinner atmosphere, if this is a Tunguska-sized impactor, it may make it intact to the surface.

Here's a simulation with its current data.  Mars, and the orbits of Phobos and Deimos are visible.  The first image is looking top-down on the ecliptic plane.  The second is from the ecliptic plane.

http://orbitsimulator.com/gravity/images/MarsHt2.GIF
http://orbitsimulator.com/gravity/images/MarsHt1.GIF

Here's the simulation file so you can run it yourself:
http://orbitsimulator.com/gravity/simulations/2007WD5.gsim

Title: Re: Asteroids
Post by frankuitaalst on 12/21/07 at 11:33:29

It really would be nice if this ast would hit Mars ( Oppurtunity and Spirit watch out ! ) as Tony mentions.
The odds of 1:75 are realistic I think .
Herunder an animation of the orbit of the ast .
I created 4 replica's of the asteroid and put them at a 1% different position in the x and y coordinates
( the uncertainty of the AU at this moment is about 1% AU at 1 sigma-uncetainty ).
This means the asteroid has a path between the -sigma and sigma with 90% ( have to look up this number ) chance.
The first frame shows Mars in the middle , to the right is the predicted path . The replicas miss Mars to the left and to the right . So theres a "good" chance the ast may hit !
The next frames show the set of asts as they  approach Mars from the lower bottom .  

Title: Re: Asteroids
Post by frankuitaalst on 12/21/07 at 13:40:20

The NASA came up with a nice article about 2007WD5 :
http://neo.jpl.nasa.gov/news/news151.html

Title: Re: Asteroids
Post by ssc4k on 12/29/07 at 18:17:25

if this asteroid hit mars what would the crater diameter/depth be?

1st post :)

Title: Re: Asteroids
Post by Tony on 12/29/07 at 20:53:10


ssc4k wrote:
if this asteroid hit mars what would the crater diameter/depth be?

1st post :)

Hi.  Welcome!
The crater should be about half a mile to 1 mile, roughly 1 km.  At least that's what I've read.  No one will know for sure until (and if) it hits.

Title: Re: Asteroids
Post by ssc4k on 12/30/07 at 13:23:46

i searched for a program that would allow you to simulate an impact of an asteroid on a planet but i couldnt find any that allowed to you to specify the density of the asteroid and the planet, does anyone here know of any?

ps. this is the best thing i found.... ( http://janus.astro.umd.edu/astro/impact/ . (it let you choose the planet and set the atmmosphere but wasnt very good at the dcensity part.)

**Edit... Your http was missing the "h" and read as ttp .  I fixed that so the link works.  -Tony

Title: Re: Asteroids
Post by Tony on 12/30/07 at 19:05:24

Thanks for the link.  The biggest problem in computing the crater size is we don't know the size or composition of the asteroid.  We have good guesses, and these can set upper and lower limits on the crater size.  We've also never seen a crater get formed aside from small craters such as the recently-formed Peruvian crater.  But large objects make craters in a different way than small objects.  Small objects simply punch a hole in the ground, no different than you throwing a rock at the ground.  But large objects create an explosion that leaves you with a round crater regardless of the incoming trajectory.

Title: Re: Asteroids
Post by ssc4k on 01/02/08 at 17:54:04

something else ive always wanted to know. what is the closes asteroid to the sun (average of the orbit)

Title: Re: Asteroids
Post by frankuitaalst on 01/03/08 at 06:37:38

The asteroid with the closest distance to the sun is the 2007EB26. The orbit is herunder :
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=+%282007+EB26%29&orb=1

Title: Re: Asteroids
Post by ssc4k on 01/03/08 at 12:40:17

hmm i thoght it would be closer than .17 au but that is pretty darn close. thanks for the link

Title: Re: Asteroids
Post by Nexus on 01/04/08 at 15:42:49

If you only take gravity into account there is a stable zone inside the orbit of Mercury from 0.08 to 0.21AU where asteroids would be able to exist without being perturbed. But gravity is not the only force involved. There is an influence called the Yarkovsky effect which can change the orbits of small asteroids. Basically what happens is that the temperature of different parts of the asteroid vary because of their rotation, irregular shape or position in its orbit (season). The warmer areas radiate more heat, which exerts a small force on the asteroid. Over millions of years this force will gradually cause the asteroid to spiral inwards or outwards. Near in to the sun the effect is stronger so the Yarkovsky effect will have cleared that area of the solar system long ago. Only large objects like Mercury, which require a huge force to accelerate them, can remain there.

Title: Re: Asteroids
Post by Tony on 01/04/08 at 18:16:58


Nexus wrote:
If you only take gravity into account there is a stable zone inside the orbit of Mercury from 0.08 to 0.21AU where asteroids would be able to exist without being perturbed. But gravity is not the only force involved. There is an influence called the Yarkovsky effect which can change the orbits of small asteroids. Basically what happens is that the temperature of different parts of the asteroid vary because of their rotation, irregular shape or position in its orbit (season). The warmer areas radiate more heat, which exerts a small force on the asteroid. Over millions of years this force will gradually cause the asteroid to spiral inwards or outwards. Near in to the sun the effect is stronger so the Yarkovsky effect will have cleared that area of the solar system long ago. Only large objects like Mercury, which require a huge force to accelerate them, can remain there.

That's interesting about the Yarkovsky effect.  I never thought about it before, but you're right, it would be huge near the Sun.  Perhaps if an asteroid is rotation-locked to the Sun then Yarkovsky won't be significant.  There's also the Poynting-Robertson effect, but I think it is less significant than Yarkovsky.

Title: Re: Asteroids
Post by Nexus on 01/05/08 at 18:40:34

Even then there would still be a small outward force because the sun-facing hemisphere would be warmer than the dark side. If the orbit has any sort of eccentricity then libration will play a part as well.

Title: Re: Asteroids
Post by frankuitaalst on 01/06/08 at 04:55:32


Tony wrote:
[quote author=Nexus link=1175113160/90#104 date=1199490169]If you only take gravity into account there is a stable zone inside the orbit of Mercury from 0.08 to 0.21AU where asteroids would be able to exist without being perturbed. .

Do you have a source describing this stable zone ?

Title: Re: Asteroids
Post by Nexus on 01/06/08 at 22:22:47

There's quite a good site on Vulcanoid asteroids here:

http://www.vulcanoid.org/faq

Title: Re: Asteroids
Post by frankuitaalst on 01/29/08 at 09:56:18

In the Baut  forum someone made the remark that in 2006 the asteroid 2004XP14 made a close pass to Earth , even closer than the present 2007TU24 asteroid .
Heres a simulation of the asteroid ( backwards running ) .
The view was taken from our sun , pointing to Earth .

Title: Re: Asteroids
Post by frankuitaalst on 02/01/08 at 12:30:13

One of the closest documentated close approaches was the approach of 2004FH to Earth in the year 2007 :
http://neo.jpl.nasa.gov/news/news142.html
Seen the Sun the encounter to Earth must have looked as following :
One dot represents the position of the asteroid in 0.5 hours. The deflection of the asteroid is very clear .
The moons orbit is represented by in thick red

Title: Re: Asteroids
Post by frankuitaalst on 03/23/08 at 14:50:18

As mentionned retrograde orbits for asteroids are very uncommon .
Here's one example of the few that are known today : the asteroid DIORETSA ( please read the name from right to left ) .
The asteroid was discovered in 1999 and is supposed to be a captured Kuiper Belt object .
It nowadays has a period of 114 years , is retrograde ( therefor its name ) and has a very elongated orbit bringing it almost as far as Pluto . The inclination is about 20° .
The orbit is very unusual . It has now some resonance properties to Pluto ( 1:2 ) and also  to Neptune .
The most remarkable feature however is its orbit instability . In its orbit it "crosses" Neptune , Uranus , Saturn and Jupiter .
Here's a simulation covering 100.000 years forward .
The innermost orbit depicted is Jupiters orbit .
Screenshots were made every 1000 years .  

Title: Re: Asteroids
Post by frankuitaalst on 03/23/08 at 15:02:40

As can be seen above the asteroid DIORETSA is almost ejected around 61.000 years.
The eccentricty keeps rising from 0.9 (now ) to almost 0.99 at 100.000 years .
I think a "close" encounter to Jupiter is the reason .
The asteroids orbit from aside can be viewed hereunder .
The outermost orbit is Pluto's orbit .
Remarkable in the animation above is the asteroids strong precession of aphelium ( counterclockwise  , regardless of its retrograde orbit ) .
The precession rate seems to be proportional to the period as the asteroid hardly shows precession at the end of the simulation .
The asteroids also seems to evolve to an orbit period of more than 1000 years !

Title: Re: Asteroids
Post by APODman on 03/24/08 at 05:00:48


Quote:
As can be seen above the asteroid DIORETSA is almost ejected around 61.000 years.  
The eccentricty keeps rising from 0.9 (now ) to almost 0.99 at 100.000 years .  
I think a "close" encounter to Jupiter is the reason .  


In my simulations using Mercury ejection really happen after 126.000 years.
The progression of eccentricty also rise  to 0.994183 at 100.000 years

And a close encounter with Jupiter ( at 0.05624548 AU ) after 43.236 years is the reason for the ejection.

Annex the file of the close encounters with Jupiter and the evoluiton of the orbital elements of Dioretsa.


[ ]´s

Title: Re: Asteroids
Post by frankuitaalst on 03/24/08 at 05:17:53

thanks for the annexes . Nice output file .
What mass did you assign to the asteroid ?
Edit : reason I ask this is the fact that I have changed the asteroids mass from arbitrarely 7e+10 to 70 kg and noticed that after 21000 years has a very close encounter with Neptune , throwing it into a very eccentric orbit . The asteroids path is very sensitive I think .

Title: Re: Asteroids
Post by APODman on 03/24/08 at 09:55:47


frankuitaalst wrote:
thanks for the annexes . Nice output file .
What mass did you assign to the asteroid ?
Edit : reason I ask this is the fact that I have changed the asteroids mass from arbitrarely 7e+10 to 70 kg and noticed that after 21000 years has a very close encounter with Neptune , throwing it into a very eccentric orbit . The asteroids path is very sensitive I think .


Hi Frank,

I use mass=0 cause the mass diference between asteroid and planets are to big to be considered.

But I will try new simulations with the mass that you test.

I will post the results here tomorrow.

[ ]´s

Title: Re: Asteroids
Post by frankuitaalst on 03/24/08 at 10:11:37

Here's the screenshot of the approach in 21.000 years , viewed from above and aside .
I can hardly imagine the mass has such a big influence to influence the asteroids path ...

Title: Re: Asteroids
Post by APODman on 03/25/08 at 06:27:43

Well,

I made a simulation of Dioretsa evolution with the mass of 700 kg.

The simulation shows some modifications: Dioretsa are ejected after 70371 years after a close encounter with Jupiter but it don´t show the great and abrupt changes of your simulation.

Maybe  this variations are because the sensibity of the initial conditions ( the chaotic component of the orbital dynamics ).

[ ]´s



Title: Re: Asteroids
Post by frankuitaalst on 03/26/08 at 15:30:32

I think the orbit of dioretsa is very sensitve to perturbations ( initial settings ) and the accurancy of calculations due to the fact that the asteriod orbits in a very elliptical orbit and has numerous encounters with the major planets .
I ran the sim again with the picard integrator once with an accurancy of 10 meters per iteration ( one interation is about 10000 hours ) and later with an accurancy of 1 meter per iteration .
The result after many years is completely different as can be seen in the following picture of the eccentricity evolution.  Time in seconds .
One can see that the eccentricity in both runs matches for some time . This corresponds to about 2000 years , or about 200 revolutions .
I think "Lyapunov" comes in after that time ....

Title: Re: Asteroids close flyby
Post by frankuitaalst on 03/29/08 at 05:11:15

Earth got a visitor some days ago : rock 2008FK flew by at 0.8 Lunar Distances .
In the next days 2008FP is expected to come as close as 0.4 LD .
Both can be seen in the following animation . Vieuwpoint is the sun .
One dot represents one hour .

Title: Re: Retrograde Asteroids Dance
Post by frankuitaalst on 03/30/08 at 11:06:45

Besides Dioretsa there are according to Wikipedia only a limited number of  asteroids in a retrograde orbit (6 in total ) .
Pictured herunder are the orbits of 4 of them :
"1999LE31", "2000 DG8","2002RP120" and "2005NP82" , the other beeing 200DG8 ( not simulated )
Animation looks to the equatioral plane .
Depicted are also the planets Jupiter and Saturn.
One of the above asteroids has a period of more than 300 years and is not always on the frames.
One frame covers 200 years . The whole sim was run for 15000 yeras.
Contrary to the Dioretsa orbit the asteroids seem to have dynamically stable orbits , but with a lot of dynamics .!
Looking from above all of them have a strong precession in the same sense as the other planets.

Title: Re: Asteroids
Post by Tony on 03/30/08 at 22:22:47

forget all about the science value.  That is one cool animation  ;D

Title: Re: Asteroids
Post by frankuitaalst on 04/01/08 at 05:36:27

The sixth known asteroid being in a retrograde orbit is known as 2004NN8.
It has a very high eccentricity ( about 0.98 ) and has an orbit bringing it far beyond Pluto's orbit .
Period is about 1000 years .
As a result the asteroid seems to spend only 50 years out of the 1000 years inside the boundaries of our solar system .
The animation shows the orbit of the asteroid over a period of 70.000 years .
Visible also are Neptunes and Plutos orbit .

Title: Re: Asteroids
Post by Nexus on 04/17/08 at 01:04:13

Turns out the asteroid Apophis is more dangerous than we thought- a kid from Germany realized that there's a chance that when Apophis makes its close pass to Earth in 2029 it could hit a satellite. The impact could change Apophis's orbit so that it becomes more likely to strike Earth on its next close pass in 2036.

Below is a link to the story.

http://www.physorg.com/news127499715.html

Title: Re: Asteroids
Post by Tony on 04/17/08 at 02:05:06


Nexus wrote:
Turns out the asteroid Apophis is more dangerous than we thought- a kid from Germany realized that there's a chance that when Apophis makes its close pass to Earth in 2029 it could hit a satellite. The impact could change Apophis's orbit so that it becomes more likely to strike Earth on its next close pass in 2036.

Below is a link to the story.

http://www.physorg.com/news127499715.html

If someone were going to challenge NASA's math, don't you think they'd be a member of this forum?  ::)

This story is already de-bunked.  NASA and ESA deny having verified the boy's claim, and are sticking with the 1 in 45000 odds.  Apophis will not be near the equatorial plane when it crosses the geosychronous altitude, so the odds of it hitting a satellite are close to nill.  Even if it did hit one, the odds are slim it would alter its trajectory enough to significantly effect the odds.  Compared to a satellite, Apophis is extremely massive.  It's the size of a football stadium... not just a football field, but the whole stadium filled with dirt.  Satellites are less massive than cars.

Title: Re: Asteroids
Post by frankuitaalst on 04/17/08 at 04:24:34

If the German boys name is something like  Einstein or Mozart it might be interesting to go over his calculations ... ;)

Title: Asteroids 2008GD110 and 2008GP3
Post by frankuitaalst on 04/17/08 at 04:40:31

The recently discovered asteroid rocks 2008GP3 and 2008GD110 come as close as ca. 3 LD from Earth .
The first one just flew by , the other will flyby in a couple of days .
Both rocks ( diam . 20-70 m ) are animated herunder .
Viewpoint is the sun .
Edit :  I have to check if I didn't put the figure upside down here  

Title: Re: Asteroids
Post by frankuitaalst on 04/17/08 at 06:32:34

Its quite uncommon that two asteroids flyby to Earth at such a small time interval .
Heres an animation ( still in 2D  :)) of the orbits of 2008GD110 and 2008GP3 in rotating frame to Earth ( little dot at 11 o' clock ) .
They don't seem to have a common origin.

Title: Re: Asteroids
Post by frankuitaalst on 04/18/08 at 08:12:59

Asteroid 2008CC71 was recently discovered and has a low Torino impact possibility .
Running the simulation I noticed it has a near resonance to Earth of 4:7.
In a rotating frame to Earth its orbit is as following .
Sim spans a time period of -50 to 90 years .

Title: Re: Asteroids
Post by Tony on 04/18/08 at 10:58:58

Nice find.  It seems like lots of asteroids are in some sort of resonance with one of the planets.  As long as this asteroid's resonance with Earth continues, it can not hit Earth.  I don't see Mars in your animation, but it seems like this asteroid is probably a Mars-crosser, which means that it one day be perturbed by Mars out of its resonance.

And it may not be in resonance at all.  Unless the errors are taken into account, and it can be demonstrated that all test asteroids within the error ellipse are in this resonance, it is difficult to conclude that this resonance exists.

I'm studying similar asteroids as part of an Independ Study class at my university.  Here's a list of some resonances I found:

http://orbitsimulator.com/astr699/ERS.html

But I have the same problem:  without accounting for the errors, I can't draw any of these conclusions.

Title: Re: Asteroids
Post by Tony on 04/18/08 at 11:18:04

Here's a stand-alone program you might enjoy:

http://www.orbitsimulator.com/gravity/DataViewer.exe

It helps you spot resonances.  To use it, create a simulation that contains a bunch of asteroids.  Use the File > Output File to create an output file.  Choose the asteroids, and choose "a (semi-major axis", "e(eccentricity)", "i (inclination)", "w (periapsis)", "rho (ascending node)", and "P".  You must not choose any more or any less, or it won't work.

Now run the DataViewer.exe
Open your output file that you created with Gravity Simulator.
You can choose the various asteroids from the list.
If you change the number that says "10", this changes the largest values that will be displayed.  For example, at 10, it will display all resonances up to 10:9 or 9:10.  If you change it to 20, it will display all resonances up to 20:19 or 19:20.

B and F change your background and foreground color, so if you want to take screen shots and print your results, you won't use all your black toner if you switch to a white background.

Here's a screenshot:
http://www.orbitsimulator.com/gravity/images/resonanceviewer.GIF

Title: Re: Asteroids
Post by frankuitaalst on 04/18/08 at 23:40:46


Tony wrote:
Nice find.  It seems like lots of asteroids are in some sort of resonance with one of the planets.  As long as this asteroid's resonance with Earth continues, it can not hit Earth.  I don't see Mars in your animation, but it seems like this asteroid is probably a Mars-crosser, which means that it one day be perturbed by Mars out of its resonance.

And it may not be in resonance at all.  Unless the errors are taken into account, and it can be demonstrated that all test asteroids within the error ellipse are in this resonance, it is difficult to conclude that this resonance exists.

I'm studying similar asteroids as part of an Independ Study class at my university.  Here's a list of some resonances I found:

http://orbitsimulator.com/astr699/ERS.html

But I have the same problem:  without accounting for the errors, I can't draw any of these conclusions.

I took a look through the link above . Really impressive ! Seems as a lot of asteroids have very funny orbits !
Concerning the 2008CC71 animation : this sim was run with the total planetary system , but the outer planets were set on "invisible". I also think Mars may disturb after some more time. Studying all the orbits within the error ellipse may take a lot of evaluation time.
 

Title: Re: Asteroids
Post by frankuitaalst on 04/19/08 at 01:16:49

I ran the 2008CC71 sim again and put it on rotating frame on Mars . Mars appears as the brown line at 6 'o clock .
The ast seems to avoid Mars for the next 70 years .
Remarkable was the fact that the orbit in rotating frame was perfectly closed after ca. 25 years .

Title: Re: Asteroids
Post by frankuitaalst on 04/19/08 at 02:39:50


Tony wrote:
Here's a stand-alone program you might enjoy:

http://www.orbitsimulator.com/gravity/DataViewer.exe

It helps you spot resonances.  To use it, create a simulation that contains a bunch of asteroids.  Use the File > Output File to create an output file.  Choose the asteroids, and choose "a (semi-major axis", "e(eccentricity)", "i (inclination)", "w (periapsis)", "rho (ascending node)", and "P".  You must not choose any more or any less, or it won't work.

Now run the DataViewer.exe
Open your output file that you created with Gravity Simulator.
You can choose the various asteroids from the list.
If you change the number that says "10", this changes the largest values that will be displayed.  For example, at 10, it will display all resonances up to 10:9 or 9:10.  If you change it to 20, it will display all resonances up to 20:19 or 19:20.

B and F change your background and foreground color, so if you want to take screen shots and print your results, you won't use all your black toner if you switch to a white background.

Here's a screenshot:
http://www.orbitsimulator.com/gravity/images/resonanceviewer.GIF

Can you provide a .gsim file with a bunch of interesting asteroids ? I want to try the viewer above . :)

Title: Re: Asteroids
Post by Tony on 04/19/08 at 10:42:06

http://orbitsimulator.com/gravity/simulations/sma0.96_0.97.gsim

This file contains all known asteroids with a semi-major axis between 0.96 and 0.97 AU, so you should find some that jump into and out of 1:1 Earth resonances and perhaps some Venus resonances.  Just remember, it is very important that you choose only the orbital elements specified in the above post, as this program is expecting the output file to be in that exact format.

You can also use it with your existing simulations such as 2008CC71, although there is probably only 1 asteroid in that simulation.  But just make more simulations the same way, including more asteroids.

Somewhere on this forum is another stand-alone program for generating .gsim files directly from JPL Horizons data.  I'll post a newer version later that lets you make sims from the searchable asteroid database.  Then you can quickly make simulations with lots of asteroids.

Title: Re: Asteroids
Post by frankuitaalst on 04/19/08 at 12:41:40

Thanks for the file ...Simulation is already running ....
If you can provide more datasets for different AU ranges there is an opportunity for distributed computing  :)

Title: Re: Asteroids
Post by frankuitaalst on 04/19/08 at 23:39:35

A question , just to make sure : the viewer expects the values a,e,i,omega,big omega and P , i.e  first to fifth and nineth checkboxes ?

Title: Re: Asteroids
Post by Tony on 04/20/08 at 00:12:57

yes

Title: Re: Asteroids
Post by Tony on 04/20/08 at 12:52:30

Here's how to automatically generate .gsim files of all asteroids in a specified range:

Visit this thread and download all the files except HorizonsAutomator.exe
http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1182042588/0#0

Download this file into the same directory
http://orbitsimulator.com/gravity/HorizonsAutomator3.exe

Visit this web page:
http://epmac.lpl.arizona.edu/search.php
and enter your desired SMA range (or any range of any orbital elements)

When your results page appears, use your browser's View > Source option to view the page source in a text editor.  Copy this text and paste it into the appropriate box in the first tab of HorizonsAutomator3.  Click the button to tell it where you got the data:  "http://emac..."

Also press "Select Planets, Dwarf Planets, Large Asteroids, and Earth's Moon" button.

Press "Create E-mails"

In the "E-mail #1 box" is the body of the e-mail you will send to Horizons.  Copy it to the clipboard.  Paste it into the body of an e-mail to horizons@ssd.jpl.nasa.gov and put the word "job" in the subject line.

Wait a few minutes for JPL to send you all the replies.  Copy these e-mail files into a folder on your computer.  This is easy to do if you use Outlook Express, as it stores all the emails as files on your computer that you can copy and paste.  But I don't know how to do this with web-based e-mail such as yahoo or hotmail.

Go to the 2nd tab of Horizons Automator:  "Build and Save .gsim file"
Browse to the folder where you stored the email files.
Press Build
Press Save As...

You should now have a .gsim file you can run.

Title: Re: Asteroids dataviewer
Post by frankuitaalst on 04/21/08 at 09:47:30

I used the dataviewer to view the sim provided listing asteroids between 0.96 and 0.97. It runs but the viewer displays a time range of 2008-2008 , although the sim was run for more than 20 years . Also the horizontal lines don't appear . Did I do simething wrong ?
In annex the .text file ( I deleted most of the after coming data ) diguised as a .gsim file
Edit : file deleted to save space ...

Title: Re: Asteroids
Post by Tony on 04/21/08 at 10:40:21

Your data only spans about 1.5 years, from 02/08 to 08/09, which is not sufficient to spot resonances.  You're also sampling your data once a day, which is too often. Nothing changes significantly in 1 day.  To display the range of years, it adds deltaT to the beginning year, which in your case is 2008.  DeltaT is simply the difference between your first data point and your second data point, which in your case is 2008-2008 or 0.  2008+0 = 2008 which is why it gives you 2008-2008.  This issue will disappear if you choose an integer number of years between data points.

1.5 years, or even 20 years won't show you anything as most resonant asteroids have libration periods in the hundreds of years.  To spot resonances, you want to run for thousands of years, so you'll have a few resonant cycles to display.  Try sampling once per year for 10000 years, or even once every 10 years for 100000 years if you want to do a longer simulation.

Title: Re: Asteroids viewer
Post by frankuitaalst on 04/24/08 at 12:54:53

Hi Tony , I created a file to view , selected the bodies as desired , also the proper elements and took 320 years of simulation . But running the viewer I don't get the horizontal lines indicating the resonances . Something other I should keep in mind ? Can you provide a sample input file just to check the viewer on my PC ?

Title: Re: Asteroids
Post by Tony on 04/24/08 at 13:58:02

Even 320 years is not much time.  If you don't get lines, its because you're too zoomed in to see the resonances you've requested.  Change the number (default=10) at the top of the screen to a higher value, and you should see pleanty of lines.

Title: Re: Asteroids viewer
Post by Tony on 04/24/08 at 16:20:31


frankuitaalst wrote:
Can you provide a sample input file just to check the viewer on my PC ?


http://www.orbitsimulator.com/astr699/sma0.96_0.97.txt
Right-click this and choose "save target as..."

Then open it in the viewer.

Title: Asteroids : Cruithne orbit
Post by frankuitaalst on 04/29/08 at 12:45:49

Cruithne is also called Earths second moon , as it is in a horseshoe orbit around Earth . A simulation of this body can be downloaded from this forum.
Running this simulation , outputting the x,y,z values and processing the data through a special visualisation program gives the following picture :
Cruithnes orbit is seen here from the viewpoint of Pluto , viewing straight to Earth . The moons orbit appears here as the little white dot in the center . Depicted also is the orbit of Venus ( in blue ) .
Frames are taken 1 year apart . So the orbit of Cruithne is almost closed due to its 1:1 resonance to Earth.
The simulation was run for 50 years . The horizontal horizon corresponds with the ecliptic plane .
From this viewpoint it seems as if Cruithne is in an orbit around Earth .

Title: Asteroids Cruithne seen from Neptune
Post by frankuitaalst on 04/29/08 at 12:50:05

Out of the next picture it may be clear that Cruithne does not orbit Earth .
Neptunes viewpoint makes clear that the asteroid is not  orbiting Earth  
Simulation also spans 50 years .
Viewangle is about 9° .  

Title: Asteroids : 2004GU9 a new moon for Earth ?
Post by frankuitaalst on 04/29/08 at 14:53:35

Here's a retake of the first asteroid in this discussion : asteroid 2004GU9.
In this view the asteroid is pictured viewed from the sun , looking to Earth .
The moon appears as the little white circle in the middle .
Angle of view is ca. 60° . Simulation covers 50 years.
Inhabitants of the sun , incapable of measuring distances might think Earth has a real second moon .  :).
Inhabitants of Neptune however are more clever ...

Title: Re: Asteroids
Post by frankuitaalst on 04/29/08 at 14:55:01

Heres the view of the Neptunians to 2004GU9 , also covering 50 years.

Title: Re: Asteroids
Post by Tony on 04/29/08 at 19:53:52

I have no idea what it means, but wow!  That last animation is cool  8-)

Title: Re: Asteroids
Post by frankuitaalst on 04/29/08 at 23:05:29


Tony wrote:
I have no idea what it means, but wow!  That last animation is cool  8-)

I also have some difficulty to interprete this orbit , but I manage to look at it as the orbit being  a patatoo chip  :-?which slightly wobbles around its equilibrium point due to libration . In the course of 50 years simulation the projection also rotates due to the motion of Neptune . If the simulation runs for as long as neptunes orbital one can view the orbit from the whole 360°.

Title: Asteroids : Achilles : Jupiter Trojan
Post by frankuitaalst on 05/01/08 at 10:57:44

The "view from" seems to be very well suited to see 1:1 resonances as fi. trojan behaviour .
Heres an example of  Achilles , a well known Trojan of Jupiter .
Viewpoint is the sun . Simulatuon spans 150 years. Jupiter appears as the yellow dot in the center .
Achilles librates around its Lagrangian point .

Title: Re: Asteroids; Jupiter Trojan Patroclus
Post by frankuitaalst on 05/01/08 at 14:33:49

Another Trojan of Jupiter is Patroclus .
This is a real "trojan" , as the Trojan population of Jupiter is divided in two "camps " : those who are leading are called "Greeks" , the other trailing ones are "Trojans" , so Achilles is -of course- a "Greek"  .
Patroclus is trailing as can be seen from the suns viewpoint .
It librates rather heavily around its lagrangian point .
Simulation covers 150 years.

Title: Asteroids : 2 Mars Trojans
Post by frankuitaalst on 05/17/08 at 14:50:22

Mars has ( according to Wikipedia) 4 known Trojans . The orbit of two of them , Eureka and 1999UJ7 are simulated herunder .
Picture is in rotating frame to Mars . Mars is  at 6 'o clock .
The quite one is Eureka .
1999UJ7 seems to be approaching to Mars .

Title: Asteroids : 2 Mars Trojans
Post by frankuitaalst on 05/17/08 at 14:55:42

Pictured from the viewpoint of the sun the orbits of both Trojans are quite different .
Mars is the little dot in the middle of the screen.
Simulation was run for 70 years .
The field of view is about 160 degrees .
In accordance to the animation above 1999UJ7 is heading to Mars .

Title: Asteroids : 4 Mars Trojans
Post by frankuitaalst on 05/18/08 at 02:50:40

For completeness I made a simulation in rotating frame to Mars showing all the known Trojans : 1990MB Eureka in red  , 1998VF31 in yellow, 1999UJ7 in red and  2007NS2 in magenta .
Result is shown herunder . Simulation starts 200 years from now and runs for another 300 years.
One can see 1999UJ7 approach  Mars from the right and then recede again .
Also 1998VF31 has this behaviour , but this one reaches its maximum at about the same time as 1999UJ7 reaches its minimum. .
The other seem to be more stable ...

Title: Asteroids : 4 Mars Trojans
Post by frankuitaalst on 05/18/08 at 02:58:20

The same simulation as above , but viewed in a perspective view from Sun to Mars ( in the middle) gives the following picture .
Here again the approach of 1999UJ7 is visible.
I noticed something strange when running this simulation . It may be a coincidence .  
All 4 Trojans seem to reach the same point in their orbit ie. the upper top of the "eight" at about the same time .
Seems as they are "synchronised" in anomaly . As the frames all cover 1.88 years this fact isn't visible in the animation .  

Title: Re: Asteroids
Post by Tony on 05/18/08 at 10:20:32

Some of your animations are similar to mine on this page:
http://www.orbitsimulator.com/gravity/articles/eureka.html
but your shapes are a little different.  I wonder if that's because you hold Mars stationary where mine lets Mars orbit its average position?  Mine is looking top-down on the ecliptic plane.  Are yours ecliptic, or orthogonal to Mars' orbital plane?

Title: Re: Asteroids
Post by frankuitaalst on 05/19/08 at 12:15:14


Tony wrote:
Some of your animations are similar to mine on this page:
http://www.orbitsimulator.com/gravity/articles/eureka.html
but your shapes are a little different.  I wonder if that's because you hold Mars stationary where mine lets Mars orbit its average position?  Mine is looking top-down on the ecliptic plane.  Are yours ecliptic, or orthogonal to Mars' orbital plane?

I took a look to your simulations . There are little  differences indeed . Without any doubt this is due to the fact that I keep Mars stationary i.e I take the immediate velocity instead of the mean orbital period.
The animation is also looking down to the ecliptic .

BTW : what is the general appearance of the animations ?
At my home computer the animations run smooth . One another ( older ) computer the animations are performing very slowly .
However : if the frames seem to freeze , it helps clicking on the link of the animation and another window pops up , running at normal velocity .


Title: Re: Asteroids
Post by Tony on 05/19/08 at 18:42:59

They appear fine.  But if they're jumpy to you, it might be because there are several displayed at the same time.  To solve this, you could put a link to your animation, rather than the animation itself so people only see 1 animation at a time.

Title: Re: Asteroids
Post by muad on 05/22/08 at 15:17:50

When I'm opening horizonsautomator3 there's something like that:  >Run time error '76': Path not found< and then when I press buttons such as 'select all' or 'create e-mail' program doesn't do that... What should I do? Thanks for any help :)

Oh yeah and I have of course American English regional settings...

Title: Re: Asteroids
Post by Tony on 05/22/08 at 17:34:41

Hi, and welcome!  I'm glad you're using external tools.  Horizonsautomator3 needs support files in the same directory.  You can get them here:
http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1182042588/0#0

Let me know if this is the problem.

Title: Re: Asteroids
Post by muad on 05/23/08 at 00:59:38

Yeah, I have these files and the problem still exists :'(

Title: Re: Asteroids
Post by frankuitaalst on 05/23/08 at 12:22:16

I have the same problem , but acknowledging the OK button gets me further ...

Title: Re: Asteroids
Post by muad on 05/23/08 at 13:29:12

OK, but then some options like Select All or send e-mail aren't working...

Title: Re: Asteroids
Post by Tony on 05/23/08 at 16:16:30

At what point do you get the error?

There is no "send e-mail" option.  It creates an e-mail for you that you must copy and paste into your own e-mail program.

I'll see if I can find the source of this error.

Title: Re: Asteroids
Post by Tony on 05/23/08 at 16:22:56

Create a folder on your computer called

C:\Program Files\Gravity Simulator\my sims\Horizons Data\

and see if that solves the problem.  This is the default folder that HorizonsAutomator3 tries to save the .gsim files it creates to.  It always gives you the option to select a different folder, so if adding this folder takes away the error, you can delte the new folder if you like and simply ignore the error.

Title: Re: Asteroids
Post by muad on 05/24/08 at 01:55:38

yes, of course  'create e-mail', my bad, sorry

error still exists, i just have to select objects one by one, by 'tick' and then i cannot create e-mail
okay, never mind, thanks for help

Title: Re: Asteroids
Post by Tony on 05/24/08 at 09:55:03

Thanks for pointing this out.  I get the same problems you do if I run the version straight off the web.  Let me look into this.

Title: Re: Asteroids
Post by Tony on 05/24/08 at 10:17:41

As best as I can tell, the line of code causing the crash is:


Code:
Open App.Path + "\planetdata.dat" For Input As #1


which basically says it is expecting to find the file planetdata.dat in the same folder as horizonsautomator3.exe

I know you've confirmed that this file exists.  I'm not sure if there's anything that European Windows does differently with filenames, preventing it from finding a file that exists.  Frank, do you have insight?  Does this program work for you, or do you get the same errors?

When I move horizonsautomator3.exe out of its folder so it is not with the support files, I get all the same errors as maud:  "File Not Found", unable to "select all", and unable to create e-mails.  But when I move it back to the same folder as all the support files, it works fine

Don't give up yet, maud!!  We'll figure it out.  This is the toughest part about sharing software:  assuming it will work fine on other computers.

Title: Re: Asteroids
Post by frankuitaalst on 05/24/08 at 14:12:43

The program does not perform smoothly on my PC either .
I get the same error as above ... but ...
I got to the link you gave , downloaded all again and ran the "zero" version , not the "3" .
The "3" does not perform any button action .
In the "zero" version I get :
Selecting "all " works , create e-mails also , but at the end I get the following message ....maybe this is a hint ...

Title: Re: Asteroids
Post by Tony on 05/24/08 at 20:25:51

At what point do you get that error?  It looks like you pressed "select all" :)

Do you get that error if you try to make simulations that are under 200 objects?

Title: Re: Asteroids
Post by frankuitaalst on 05/25/08 at 00:39:38

The program ; without index "3" works !  :).
I selected all the planets and some asteroids ... and created an e-mail .
Thats fine !
Maybe the program "3" has some difficulty with the / in the filename , as the typeboard in Europe has other characters ?
Do you need the full drive name in Vbasic ? In Powerbasic I only use the filename to import files in a program .

Title: Re: Asteroids
Post by frankuitaalst on 06/01/08 at 14:57:17

I came to this particular asteroid through another post .
1999TZ1 is a Jovian asteroid , about 51 km wide , in the L5 point but with a srtong dynamical orbit .  Its a miricle this asteroid is stable ...
8-) In the animation herunder  one can see the asteroid as seen from the sun , viewing to Jupiter .
Simulation was run for ca. 45 years .
The picture shows that an orbit around a "L" point orbit isn't really a static orbit but can show a lot of dynamics...

Title: Asteroids : june 2008 close encounters
Post by frankuitaalst on 06/03/08 at 13:13:29

Between june 1st and 9th Earth got 4 close encounters with the following asteroids :
2008KO, 2008KT, 2008LD and 2008LB, ranging from 3.4 to 1.1 Lunar Distances .
Heres a animation of this flybys . First part shows the view from Sol .
8-) Second part shows the same viewpoint but in 3D anaglyph .
1 Frame corresponds with 36 days .  There seems not to be an orbital connection between the four asteroids . It is quite unusual to have 4 close flybys in such a short time .
Clicking on the icon above opens a new window wich in my opnion gets the best view.

Title: Asteroids : 1999TZ1's heartbeat ..
Post by frankuitaalst on 06/04/08 at 10:18:20

What's causing asteroids 1999TZ1 heartbeat as shown in the simulation herunder ?
I don't know .
1999TZ1 is a Jovian Trojan orbiting in a high inclinated orbit . The SMA seems to pulsate in a rather regular way .
Animation spans for 400 years . every frame covers 11.86 years . Jupiter and the ast are viewed from above .
Running the simulation for a much longer time gives a precession of perihelion , but also a pulsating change of the perihelion .
Where the perihelion is at 2 'o clock the perihelion shifts to 8 'o clock periodically .
??.

Title: Re: Asteroids
Post by Tony on 06/05/08 at 14:22:32

It's probably just an artifact of the viewing angle.  For example, the following image can be perceived as the planets having 2 perihelions each:  one at 12 o'clock and 1 at 6 o'clock.
http://www.orbitsimulator.com/gravity/articles/ssystem.GIF
If its a trojan, the semi-major axis should pulsate, causing a periodic change in its orbital period making it drift ahead of and behind the Lagrange point.

Title: Re: Asteroids
Post by frankuitaalst on 06/05/08 at 22:55:48


Tony wrote:
If its a trojan, the semi-major axis should pulsate, causing a periodic change in its orbital period making it drift ahead of and behind the Lagrange point.

Yes its a Trojan of Jupiter, and you're right :it should pulsate , but it"s the first time I observe this this clear.  I made a picture of the evolution of SMA and inclination . Eccentricity however is stable. Both pulsate and are dephased over 180° . I wonder what gives this long period , seeming to be about 175 years .
Any idea how the pulsation frequency is related to the major body's orbital period ?

Title: Asteroids: a big one is on its way : 2008BT15
Post by frankuitaalst on 06/06/08 at 09:26:16

2008BT15 must have been discovered long time ago , but for some reason it has a 2008 designation .
It has a diameter of about 1 km and will come as close as 5.9LD on july 14th .
Herunder is a frozen picture of its path in anaglyph showing the orbit seen from the sun centered on earth . The line in the middle represents moons orbit.
The asteroid comes from the left , seems to make a loop and approaches Earth going to the left again .
If the 3D glasses work fine the asteroid should come out of the screen at the right . Is it ?

Title: Asteroids- very eccentric
Post by frankuitaalst on 12/28/08 at 12:30:31

I've made a selection of two asteroids with very high eccentricity .
Here they are 2006HY51 and 2008HW1. Both have eccentricities above 0.95.
They seem to be twins in this animation ...
They might  have been  twins , although they're separated in inclination by about 20°.
Moreover :the orbits of the minor plantes Ceres , Pallas , Juno , Vesta and Hygiea are the greyscaled orbits .
It's funny : 3 of them seem to go through one point .
Lets take another look in another thread

Title: Asteroids : first big one of 2009 discovered
Post by frankuitaalst on 01/04/09 at 03:31:48

Maybe an early gift of 2009 :
On 02/01/2009 this really big asteroid was discovered . It ranks highest in Palermo scale among the newly discovered ones with an estimated diameter of about 900 meters .
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009+AV;orb=1.
The orbital parameters still show a lot of sigma ( sma = 0.88 +/- 0.14sigma) after only 10 observations .
Remarkable is the fact that 2009AV must have been closer to earth in the past years , so it's a mystery to me why this one hasn't been discovered earlier ...
The animation herunder shows the most likely orbit in rotating frame to Earth . Animation starts at 01/02/2007.
The green dot in the last picture shows the approximate location of 2009AV at the time of discovery .
As more observations will become available I'll try to update if necessary .

Title: Re: Asteroids
Post by NeutronStar on 01/04/09 at 12:24:06

WHere can I get the Horizons Automator. It looks cool!

Title: Re: Asteroids
Post by Tony on 01/04/09 at 14:40:06

You can find it here:
http://www.orbitsimulator.com/cgi-bin/yabb/YaBB.pl?num=1182042588

Title: Re: Asteroids
Post by NeutronStar on 01/04/09 at 18:03:25

Okay.

Title: Re: Asteroids : first big one of 2009 discovered
Post by frankuitaalst on 01/10/09 at 06:58:06


frankuitaalst wrote:
Maybe an early gift of 2009 :
On 02/01/2009 this really big asteroid was discovered . It ranks highest in Palermo scale among the newly discovered ones with an estimated diameter of about 900 meters .
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2009+AV;orb=1.
The orbital parameters still show a lot of sigma ( sma = 0.88 +/- 0.14sigma) after only 10 observations .
Remarkable is the fact that 2009AV must have been closer to earth in the past years , so it's a mystery to me why this one hasn't been discovered earlier ...
The animation herunder shows the most likely orbit in rotating frame to Earth . Animation starts at 01/02/2007.
The green dot in the last picture shows the approximate location of 2009AV at the time of discovery .
As more observations will become available I'll try to update if necessary .

New observations of the asteroid solve the mystery why it wasn't detected earlier : the initial orbit has changed dramatically in this sense the asteroid actually moves slower than Earth and is approaching ...
The danger for a collission seems to be gone with a MOID of 0.02AU .
Herunder is an animation of the path of the asteroid in rotating frame to Earth . The fisrt part is a top view , the second part shows a side view. The "old" orbit is in grey , the newly calculated orbit is shown in white ...


Title: Re: Asteroids
Post by NeutronStar on 01/10/09 at 09:04:04

I was looking through asteroids on there and I found that. COOL! I didn't know it was that big.

Title: 2000SG344 : a nerveous asteroid
Post by frankuitaalst on 01/17/09 at 05:49:45

2000SG344 is a small asteroid measuring only 40 meter s in diameter .
Currently it is one of the asteroids having the biggest chance for collision with Earth . It ranks lower than Apophis due to its lower mass .
The asteroid will make numereous close encounters with Earth in the future ( as it did in the past also) .
Each close encounter changes it's orbit , sometimes in a dramatic way .
Herunder is an animation of its orbit over the next 500 years in time frames of 10 years ...

Title: Re: Asteroids
Post by NeutronStar on 01/17/09 at 09:53:33

Why did yo change the objects colors

Title: Re: Asteroids
Post by frankuitaalst on 01/17/09 at 10:03:51

I didn't change anything . What you see is Earth in blue and moon in silver .

Title: Re: Asteroids
Post by NeutronStar on 01/17/09 at 11:53:56

Mercury in yellow-green and venus in blue. Mine is mercury in gray and venus in... I forgot.

Title: Asteroid : update of Neo from JPL
Post by frankuitaalst on 01/22/09 at 12:58:26

JPL announces to have updated the known risks for asteroids .
http://neo.jpl.nasa.gov/risk/
Haven't yet read the paper but its remarkable that two "old" known preditors 2001WN5 and 1999RQ36 have been promoted ito the top in the risk ranking .
These two guys are really big ....
As far as I can see now the risks rise because the new system evaluates the risk over more than 100 years , where the previous system cut at 100 years .
Maybe even other asteroids will be promoted the next days.

Title: Asteroids : 2009BD : temporary moon
Post by frankuitaalst on 01/26/09 at 10:39:12

THe Baut Forum ( Universe Today ) announced today the detection of a stalking moon to Earth : 2009BD
The body is only 10 m across and will come as cloes as 1.8 LD . Moreover it is claimed it will stay as another moon for some time .
I simulated this one a couple of days ago . One may see in this rotating frame the asteroid will make some revolutions around Earth , but will leave soon . ( in this sim at 02/05/2011 after a close encounter of 0.0023 AU ) .

Title: Re: Asteroids
Post by Tony on 01/26/09 at 12:59:33

I made a reply on the BA's blog about this asteroid yesterday:

It seems this asteroid doesn't quite deserve all the attention its getting.  Despite what's been reported, It is not co-orbital with Earth.  Co-orbitals can't come this close to Earth.  Using JPL's numbers, here's some diagrams of 2009 BD's orbit.

This image shows its trajectory during its 4-year stint in Earth's vicinity.  This image was made in a rotating frame, which would keep the sun still if the image were zoomed out enough to show the sun.
http://orbitsimulator.com/gravity/images/2009BD_2.GIF

The next image shows the next 20 years of its orbit.  This is also in a rotating frame.  There's nothing in this trajectory that suggests that this asteroid is co-orbital with Earth.
http://orbitsimulator.com/gravity/images/2009BD.GIF

Title: Re: Asteroids
Post by frankuitaalst on 01/26/09 at 13:45:34

The asteroid escapes , isn't it  ? ( around may 2001 ? )
BTW : how do you manage to add time stamps ?

Title: Re: Asteroids
Post by Tony on 01/26/09 at 14:24:07

It was never really captured, so I wouldn't use the word 'escape'.  But in 2011 it makes a very close pass to Earth, closer than the moon, which pumps up its sma, extending its period, making it less Earth-like, so rapidly departs Earth's vicinity.

The time stamps?  I just photoshop them in afterwards. ;D

Title: Asteroids : 200BD from sun
Post by frankuitaalst on 01/27/09 at 11:05:14

In order to complete the "picture" of this odd stalking asteroid I made this animation :
Viewpoint is the sun , looking at Earth .
Moons orbit is shown in white .
One can see the asteroid approaching from the left , make some revolutions and then "leaves" after a close approach around May 2011.
Each frame covers 0.05 years . The animation starts 1 year ago .  

Title: Asteroid 2009BD
Post by frankuitaalst on 01/28/09 at 12:46:27

Where does the asteroid come from ?
In the Baut Forum someone remembered another celestial body was later identified as being a part of afaik a Saturn rocket  , and had the thought also 2009BD might be a human made object , given it small size ( several meters) .
It's possible ...if the current orbit varies from the nonimal orbit .
Given the JPL nominal orbital parameters the object must have been close to Earth around june 1955, at a distance of about 0.003 AU .
This close approach was two years before the first Russian Sputnik , which was I think the first launched sattelite , so  this object is probably not man made  .
In annex a simulation in rotating frame to Earth , going back in time .

Title: Re: Toutatis
Post by NeutronStar on 01/31/09 at 20:08:16

This is something when I was going through my gsims.

Title: Re: Asteroids
Post by Tony on 01/31/09 at 21:48:42

Toutatis is in resonance with Jupiter.  If you hold Jupiter still, it looks like the animation on this page:
http://www.orbitsimulator.com/gravity/articles/toutatis.html

Title: Re: Asteroids
Post by NeutronStar on 02/01/09 at 07:36:10


Tony wrote:
Toutatis is in resonance with Jupiter.  If you hold Jupiter still, it looks like the animation on this page:
http://www.orbitsimulator.com/gravity/articles/toutatis.html


Neat! I thought that if it cam close passes of earth 2 times in the last 5 years, that it would be in resonance with Earth, but against Jupiter, it has no power.

Title: Re: Chariklo 4:3 with Uranus
Post by NeutronStar on 02/12/09 at 16:47:52

;D

Title: Re: Chariklo 4:3 with Uranus
Post by kheider on 02/13/09 at 09:30:17


NeutronStar wrote:
;D


Hi NeutronStar;

Nice animation.  I had not thought about the Centaur Chariklo.  I know that Chariklo is suppose to be near the 4:3 Uranus resonance. (Horner 2004)  I suppose this animation is showing Chariklo "displaying resonant like behaviour".

Simulations of the Population of Centaurs I: The Bulk Statistics
http://arxiv.org/abs/astro-ph/0407400v1  (click PDF in upper right to read article)
Ctrl-F (Text Find/search) 4:3
-- Kevin

Title: Re: Asteroids Chariklo
Post by frankuitaalst on 02/13/09 at 12:13:51

Unfortunately Chariklo doesn't seem to have a 4:3 resonance to Uranus if we keep Uranus fixed .
The pattern is very unusual but the orbit doesn't match a resonance  
Animation was run for 20.000 years .  

Title: Re: Asteroids Chariklo
Post by NeutronStar on 02/13/09 at 12:32:47


frankuitaalst wrote:
Unfortunately Chariklo doesn't seem to have a 4:3 resonance to Uranus if we keep Uranus fixed .
The pattern is very unusual but the orbit doesn't match a resonance  
Animation was run for 20.000 years .  

how come my chairiklo seems to liberate? And how do you get your planets in a straight line, mine make an oval?

Title: Re: Asteroids Chariklo
Post by kheider on 02/13/09 at 22:55:50


frankuitaalst wrote:
Unfortunately Chariklo doesn't seem to have a 4:3 resonance to Uranus if we keep Uranus fixed .
The pattern is very unusual but the orbit doesn't match a resonance  
Animation was run for 20.000 years .  


I am glad that Chariklo does not show a resonance.  Other wise it would likely be in conflict with the findings of Horner 2004.  The current JPL orbital data is based on 532 observations spanning 20 years (through 2008-07-03) with an orbit quality of 1.  So it is near the resonance but misses it.

I would be curious to see how 55576 Amycus (2002 GB10) behaves itself.
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2002GB10

-- Kevin

Title: Re: Asteroids Chariklo
Post by frankuitaalst on 02/13/09 at 23:37:12


NeutronStar wrote:
how come my chairiklo seems to liberate? And how do you get your planets in a straight line, mine make an oval?

In order to get the resonance presented you should adapt the rotating frame setting to the correct orbital period . This makes the primary stable . This wasn't the case in your animation .
Once this is done Uranus will make an oval which will stay at its location . One can also take the asteroid as the primary , but this isn't generally done .
The reason why Uanus makes a straight line in my visualisation is that I used my own simulator (similar to GravSim ) . Here I adapt the screenshot continiously in order to position the orbit of the primary at a fixed angle . So while the angle is fixed Uranus orbit shows up as a line due to its eccentricity .
If eccentricity would be zero the primary will show up as a point .

Title: Re: Asteroids Chariklo
Post by frankuitaalst on 02/14/09 at 02:50:51

[quote author=kheider link=1175113160/195#204 date=1234594550
I would be curious to see how 55576 Amycus (2002 GB10) behaves itself.
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2002GB10

-- Kevin[/quote]
First screenshots show Amycus isn't behaving ..Seems to be a rebel...
>:(

Title: Asteroid Amycus
Post by frankuitaalst on 02/14/09 at 03:29:43

Amycus seems to be sandwitched between the orbits of Uranus and Neptune .
The animation covers ca. 25.000 years . Uranus appears in rotating frame to it as the blue line at 3 'o clock . ( each frame covers 3*84.07 yeras) .
Neptune in white .
Amycus can hold its wildly librating 3:2 resonance to Uranus for about 12.000 years , but then , probably due to a to close encounter with Uranus it breakes up the resonance.

Title: Re: Asteroids Chariklo
Post by NeutronStar on 02/14/09 at 09:26:05


frankuitaalst wrote:
[quote author=NeutronStar link=1175113160/195#202 date=1234557167]
how come my chairiklo seems to liberate? And how do you get your planets in a straight line, mine make an oval?

In order to get the resonance presented you should adapt the rotating frame setting to the correct orbital period . This makes the primary stable . This wasn't the case in your animation .
Once this is done Uranus will make an oval which will stay at its location . One can also take the asteroid as the primary , but this isn't generally done .
The reason why Uanus makes a straight line in my visualisation is that I used my own simulator (similar to GravSim ) . Here I adapt the screenshot continiously in order to position the orbit of the primary at a fixed angle . So while the angle is fixed Uranus orbit shows up as a line due to its eccentricity .
If eccentricity would be zero the primary will show up as a point .
[/quote] I used the preset thing... but why does it liberate?  :-? I don't understand

Title: Re: Asteroids Chariklo
Post by NeutronStar on 02/14/09 at 09:30:16


frankuitaalst wrote:
[quote author=NeutronStar link=1175113160/195#202 date=1234557167]
my visualisation is that I used my own simulator (similar to GravSim )

Can I download it, or do you think it would be confusing?

Title: Re: Asteroids Chariklo
Post by frankuitaalst on 02/14/09 at 14:34:35

[quote author=NeutronStar link=1175113160/195#208 date=1234632616
Can I download it, or do you think it would be confusing?[/quote]
I'm afraid the simulator isn't very useful for the public . It misses a lot of nice input and output features GravSim has . Input has to be done manually and there's no correction possible once the sim is started .
I use both programs . GravSim is much better for input and visualisation and performs very well even for large systems.  One advantage : the integrator adapts its timestep in order to get a preset accurancy .  We once tried to combine the integrator with GravSim but this wasn't a succes till now.

Title: Asteroids close aproaches to Earth Okt 2010
Post by frankuitaalst on 10/18/10 at 22:42:33

Recently Earth got 4 visitors within 1 Lunar Distance :

2010 RF12
2010 UE
2010 TE55
2010 TG19

The animation was generated with a timeframe of 1 day

Title: Re: Asteroids Okt 2010
Post by frankuitaalst on 10/18/10 at 23:07:25

I see I overlooked one : 2010 TD54 .
Here's the total picture

Title: Re: Asteroids : 2005 YU55 close approach
Post by frankuitaalst on 03/14/11 at 10:55:43

According to the neo site : http://neo.jpl.nasa.gov/news/news171.htm the asteroid 2005YU55 , some 400 m in diameter will make a close appraoch wihin the Lunar distance in november this year .

Hereunder is an animation from different viewpoints depicting this event .

the first frames show the approach as seen from the sun in a 2° field . The asteroid comes from the right , comes near and then "returns" going upwards to continue its orbit . The reversal is due to the fact that the angular velocity of the asteroid becomes smaller than earths angular velocity .
the second frames show the asteroid as seen from above , centered on earth . Each dot represents 0.5 hours .
the last part gives an overview of the solar system showing the effect of the close approach on the asteroids orbit .

Clicking on the frame in the link also starts an animation which is also worthwile viewing ....

Title: Asteroid 2011MD close approach to Earth
Post by frankuitaalst on 06/23/11 at 12:52:33

Asteroid 2011MD will make a cloes pass to Earth on 27th june , within 0.05 LD .
Here's a screenshot showing the path in yellow , relative to Earth.
Earth is marked with the white line . In this view the asteroid moves upward.  

Title: Re: Asteroids
Post by Tony on 06/23/11 at 19:08:17

Here's a .gsim of 2011 for anyone who wants to play with this asteroid (or perhaps space junk).  It's amazing how close this thing gets!
http://www.orbitsimulator.com/gravity/simulations/2011MD.gsim

Title: Asteroid 2011MD
Post by frankuitaalst on 06/25/11 at 03:25:03

Thanks Tony for the gsim .
I believe if the orbit changes color then the object is under the ecliptic ? Am I right ?

I've run the sim in 3D also .
Here's a screenshot as viewed from the suns perspective .
In this view the asteroid comes from the right above and leaves Earth to the left above .
One pixel represents one hour .
It is obvious how the asteroid is accelerated as he approaches Earth . A very nice slingshot !
At closest encounter its speed is about 90° in two hours ; this will be hard to follow by telescope

Title: Re: Asteroids
Post by Tony on 06/25/11 at 11:35:00

I have a new LED monitor, and I'm not getting the 3d effect as well as on my old CRT.  Can you make a 3d animation?

Title: Re: Asteroid 2011MD
Post by frankuitaalst on 06/26/11 at 01:20:16

Here's a 3D animation with viewpoint from sun .  
In reference of the previous picture I've optimized the parallax in order to get a better view . Increasing the parallax would result in a worser depth view as our eyes may have difficulties to get focus.
I've noticed that in order to get a maximum effect its a good idea to have no screens open with a white texture.  

Title: Re: Asteroids
Post by Tony on 06/26/11 at 11:07:45

Thanks Frank.  I'm still having trouble.  Perhaps its the new monitor.

Title: Re: Asteroid 2011MD
Post by frankuitaalst on 06/27/11 at 07:30:37

Please check out this site :
http://www.frankdeboosere.be/nieuws/news2011/news2011.php
maintained by our national weather forecast man Frank De Boosere .
Sigh , wished I had this software too  :-X

Edit : I think the above animations come from this Rumanian site :
http://sonkab.wordpress.com/2011/06/25/mic-asteroid-trece-pe-langa-terra/

Edit : originally this site may be the original : http://orbit.psi.edu/~tricaric/2011MD.html

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