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Asteroid May Hit Mars on January 30, 2008 (Read 18481 times)
APODman
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #15 - 12/28/07 at 10:39:31
 
Thanks by the help Tony,
 
I will try simulate again.
 
 
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Nexus
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #16 - 12/28/07 at 13:54:14
 
I wonder if the Spirit or Opportunity robots on Mars will have a good view of the close encounter.
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frankuitaalst
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #17 - 12/28/07 at 14:05:53
 
I'm afraid their resolution is not good enough . The size of the asteroid is estimated at about 50 meters across.  The object is to dim to detect for them .  
The MRO , orbiting Mars , has better resolution . It might catch the asteroid if its position is well .
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frankuitaalst
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #18 - 12/28/07 at 14:14:35
 
A question for Tony : do you have any idea how to translate a given deviation of a , e...etc in a deviation of x,y,z , vx, vy, vz ?  
x, y, z may be simple , but how about vx,vy,vz ?  
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #19 - 12/28/07 at 19:37:02
 
Quote from frankuitaalst on 12/28/07 at 14:14:35:
A question for Tony : do you have any idea how to translate a given deviation of a , e...etc in a deviation of x,y,z , vx, vy, vz ?
x, y, z may be simple , but how about vx,vy,vz ?

The formulas are included in Gravity Simulator, so it's probably easiest to use Gravity Simulator rather than directly use the formulas with a calculator.
 
Let's say for example that your SMA is 1 AU with a 1 standard deviation of 0.1 AU
 
menu Objects > Create Objects
Create 1 object with an SMA of 1 AU, and whatever numbers you want for the other elements
Create 1 object with an SMA of 0.9 AU, and the same numbers you used for the 1st object
Create 1 object with an SMA of 1.1 AU, and the same numbers you used for the 1st object
 
Now use menu Objects > Edit Objects to view their x,y,z, vx, vy, vz.
 
Let me know what you get.  I've been wanting to populate the region of uncertainty from the elements in the link you earlier provided, but I haven't had time yet.
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #20 - 12/28/07 at 19:42:24
 
NASA now sets the odds at 1 in 25 after finding pre-discovery photos.  But Horizons hasn't updated its numbers yet:
 
http://neo.jpl.nasa.gov/news/news153.html
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frankuitaalst
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #21 - 12/29/07 at 01:33:41
 
It's weird : the observations of nov 8th appear in the list of Neodys.  
http://131.114.72.13/cgi-bin/neodys/neoibo?objects:2007WD5;obs;1;200
The Apache Point observatory made some observations at that time . Maybe they are already included in the predictions ?  
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #22 - 12/29/07 at 01:55:06
 
If it misses, the asteroid orbit's surely going to be changed considerably, right? Could it swing back for another possible impact?
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frankuitaalst
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #23 - 12/29/07 at 09:15:44
 
As far as I can get out of the simulation provided by Tony the deflection of the asteroid is rather "small" ie. not a big bending . As the asteroid is not really attracted by Mars , but is rather "by accident " heading to Mars it will not stay in Mars' influence and continue its way . After some decades it will be again in the neighbourhood of Earth . See link herunder .  
http://131.114.72.13/cgi-bin/neodys/neoibo?objects:2007WD5;main
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frankuitaalst
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #24 - 12/30/07 at 09:03:03
 
I made a simulation  to show what happens after the close approach to Mars .  
Light green is the present prediction . Dark green is one of the earlier predictions.  
The arrow indicates the point of closest approach to Mars.
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2007WD5ChangeAnim.gif
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frankuitaalst
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #25 - 01/01/08 at 04:45:08
 
New observations are avalable .  
Seems that the distance to Mars has increased to 238e-6 AU.
Source : Neodys
Planet Date MJD Nominal Distance (AU)  
MARS  2008/01/30.51234  0.0002389  
 
For some reason the JPL site which generates the ephemeris is out now.
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #26 - 01/01/08 at 13:06:53
 
Quote from frankuitaalst on 01/01/08 at 04:45:08:
New observations are avalable .
Seems that the distance to Mars has increased to 238e-6 AU.
Source : Neodys
Planet Date MJD Nominal Distance (AU)
MARS  2008/01/30.51234  0.0002389

For some reason the JPL site which generates the ephemeris is out now.

It seems the JPL sites are down today.  Horizons still responds.  It does not indicate any new observations have been made.  But the site http://newton.dm.unipi.it/cgi-bin/neodys/neoibo?objects:2007WD5;obs;1;200 mentions 2 additional observations, one on the 29th, and a group of 3 on the 31st
I don't know how to interpret the Neodys table.  What does Stretching and Width mean?  Although the nominal path is further, what has happened to the error bars?
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frankuitaalst
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #27 - 01/01/08 at 14:05:16
 
I don't know what they mean with streching and width . ( maybe it is the error along the path and the width of the path ??) . I have send an email to neodys for more information about this .  
My guess is that the error should be smaller as there is an extra observation ( sigma is reduced ) .  
It may be possible by now that Mars isn't anymore within the error ellipse.  
 
Note : as I was typing I saw the site is available again , but the new observations aren't yet in it .
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #28 - 01/01/08 at 14:15:02
 
The minimum distance is 2468 km, which is less than Mars' radius, so I don't think its out of the oval yet.  I wonder if minimum distance means 1 sigma?
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frankuitaalst
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Re: Asteroid May Hit Mars on January 30, 2008
Reply #29 - 01/02/08 at 14:23:14
 
The new observations of 2007WD5 of 31/12/2007 came in ...
Heres the picture of the latest simulation .  
The nominal distance to Mars has increased to 238E-6 AU , ie almost the double of the estimated distance on 23/12/07 . So the chances of a collosion become smaller . Mars was drawn manually in the following picture .
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2007WD5Rev0201.gif
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