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Message started by Tony on 10/14/15 at 19:27:56

Title: Lunar trojan asteroid
Post by Tony on 10/14/15 at 19:27:56

It's difficult to get objects to stay at the Moon's L4 & 5 points.  Here's a hypothetical asteroid orbiting Earth as a Lunar Trojan.  The starting conditions were obtained from John Chambers.
http://orbitsimulator.com/gravitySimulatorCloud/simulations/1444874023132_Lunar_Trojan.html

Title: Re: Lunar trojan asteroid
Post by frankuitaalst on 10/15/15 at 14:38:05

Waw !  Definitevely some debris must be "there" , afaik I haven't herad of .
Would it be possible to generate a companion in the other ( l4 or L5 point ) ?

Title: Re: Lunar trojan asteroid
Post by Tony on 10/15/15 at 22:27:48

There probably aren't any there according to Chamber's paper: http://www.researchgate.net/publication/229330972_Solar_and_planetary_destabilization_of_the_EarthMoon_triangular_Lagrangian_points
With only the Sun included, this orbit should last for billions of years.  But add the perturbations of the planets, and this trojan probably only lasts millions of years.  The planets are included in my simulation, but it would take a few weeks to simulate, so I haven't tried it.

A few years ago, Chambers sent me data for 81 objects, but they all seem to have similar LAN and peri, so they're all at L4.

I tried moving it to L5 simply by subtracting 120 degrees from its MA.  It worked, but in only lasted a few months at L5.
You can try it.  Objects> Edit Objects (Elements).  Choose "object" with reference of "Earth" and change the MA.  I'm guessing there are some configurations that would work, but it's not as easy as simply shifting it by 120 degrees.

Title: Re: Lunar trojan asteroid
Post by frankuitaalst on 10/16/15 at 15:02:37

I tried the L5 point substracting ca.  120° .  Initial Ma : 308 to 311 , different  values , keeping all other elements the same as the "object" .  
Some lasted for ca. 3-5 years in L5 .
Maybe modifying some other elemnts may yield a longer stability , but indeed I have the impression one should generate a bunch of clones in order to get some more stability .

Title: Re: Lunar trojan asteroid
Post by frankuitaalst on 10/17/15 at 03:47:19

Hi Tony ,
I see in the html version there is a new method for adding clones . I would like to do this for a moon in the L5 point .
Can you give some information how this feature works ?

Title: Re: Lunar trojan asteroid
Post by Tony on 10/17/15 at 12:51:54

"Create Object With Clones" is for creating clones of an asteroid from a covariance matrix.  It's not what you would want to use to create the L5 clones.  Instead, use "Create Objects".  
Set the reference object to the L5 object.  Choose the number of objects you want.  Set their SMA to perhaps a few thousand kilometers.  For Inclination, Longitude, and Periapsis, change them from 0 to 180 degrees.  After the +/-% buttons, change all the 0s to 100 for each orbital element.  That should give you a nice random cloud of particles around your L5 object.

I'll make another thread with instructions on how to use the clones feature.

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