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Asteroids (Read 146764 times)
frankuitaalst
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Re: Asteroids
Reply #135 - 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  Smiley
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frankuitaalst
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Re: Asteroids
Reply #136 - 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 ?
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Re: Asteroids
Reply #137 - 04/20/08 at 00:12:57
 
yes
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Re: Asteroids
Reply #138 - 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.
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frankuitaalst
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Re: Asteroids dataviewer
Reply #139 - 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 ...
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« Last Edit: 04/21/08 at 12:51:19 by frankuitaalst »  
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Tony
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Re: Asteroids
Reply #140 - 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.
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frankuitaalst
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Re: Asteroids viewer
Reply #141 - 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 ?
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Re: Asteroids
Reply #142 - 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.
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Re: Asteroids viewer
Reply #143 - 04/24/08 at 16:20:31
 
Quote from frankuitaalst on 04/24/08 at 12:54:53:
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.
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Asteroids : Cruithne orbit
Reply #144 - 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 .  
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CruithnePluto.gif
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Asteroids Cruithne seen from Neptune
Reply #145 - 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° .
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CruithneNeptune.gif
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Asteroids : 2004GU9 a new moon for Earth ?
Reply #146 - 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 .  Smiley.  
Inhabitants of Neptune however are more clever ...
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2004GU9toEarth.gif
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frankuitaalst
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Re: Asteroids
Reply #147 - 04/29/08 at 14:55:01
 
Heres the view of the Neptunians to 2004GU9 , also covering 50 years.
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2004GU9Neptune.gif
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Re: Asteroids
Reply #148 - 04/29/08 at 19:53:52
 
I have no idea what it means, but wow!  That last animation is cool  Cool
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frankuitaalst
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Re: Asteroids
Reply #149 - 04/29/08 at 23:05:29
 
Quote from Tony on 04/29/08 at 19:53:52:
I have no idea what it means, but wow!  That last animation is cool  Cool

I also have some difficulty to interprete this orbit , but I manage to look at it as the orbit being  a patatoo chip  Huhwhich 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°.  
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