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undormant

Banned

Registered: 2012-03-25

Posts: 18

Move Mars To L4 / L5

Hi, I've recently learnt a bit about l1-l5 and it's very interesting.

If you could move a planet say Mars to l4/l5 would it remain a constant distance from Earth in the orbit, always trailing behind?

I presume Venus is too big?

What is the maximum size of the body in the l4/l5 range?

I've probably misunderstood the concept so please help I find it very interesting.

It seems obvious worlds would rarely develop naturally this way but if terraformers a thousand years from now could do this it opens up worlds of opputunity.

R

Terraformer

Member

From: Ceres

Registered: 2007-08-27

Posts: 3,817

Website

Re: Move Mars To L4 / L5

The system is stable for, I recall, a mass 1/22th of the smallest body. So it wouldn't be stable, in the case of Mars. Indeed, the prevailing hypothesis for the formation of Luna was a Mars sized body forming there and hitting Terra...

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"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

undormant

Banned

Registered: 2012-03-25

Posts: 18

Re: Move Mars To L4 / L5

Sorry I wasn't clear I was talking about sun-earth l4/l5 does this make a difference to the calculation, I didn't mean earth-moon.

R

Tom Kalbfus

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Registered: 2006-08-16

Posts: 4,401

Re: Move Mars To L4 / L5

Problem is getting it there. A planet, if it is to m moved at all, has to be moved gradually, so moving Mars involves in spiraling towards the Sun and thus closer to Earth orbit, if it gets too close there is a danger of collision!

undormant

Banned

Registered: 2012-03-25

Posts: 18

Re: Move Mars To L4 / L5

We're going to assume the planet can be moved in some distant future for the purpose of this hyperthetical situation.

I'm more concerned as to whether Mars or Venus would be stable in the sun-earth L4/L5 range.

R

Tom Kalbfus

Banned

Registered: 2006-08-16

Posts: 4,401

Re: Move Mars To L4 / L5

Venus would not be, but there is another solution, there are two satellites of Saturn which exchange orbits with each other, Janus and Epimetheus are called co-orbital moons.[16] They are of roughly equal size, with Janus being slightly larger than Epimetheus.[34] Janus and Epimetheus have orbits with only a few kilometers difference in semi-major axis, close enough that they would collide if they attempted to pass each other. Instead of colliding, however, their gravitational interaction causes them to swap orbits every four years.[41].
http://en.wikipedia.org/wiki/Moons_of_Saturn

What if we had a co-orbiting Earth and Venus? One potential problem may be the tidal effects that occur when Venus and Earth have to pass close to exchange orbits. I don't know what the minimum distance would be for an orbit swap

undormant

Banned

Registered: 2012-03-25

Posts: 18

Re: Move Mars To L4 / L5

That's an interesting concept I wonder how stable that would be for the planets I'd be paranoid living in a system like that!

Anyone able to answer my question?

R