# Asteroid gravity

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Would it be possible to give the E class asteroids gravity of like 0.0001 G so you would have an actual ability to land a light probe on it and have I fight the gravity of it to dock to it it would make the game more realistic and challenging also the smaller they are the lighter the gravity just a thought so you could in theory orbit them but it would be really hard just like real asteroids.

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I have been hoping for this for so long. Yes! GRAVITY!!!

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All asteroids are considered parts to KSP, so adding gravity to asteroids in stock is impossible. However, procedural asteroid "planets" might be possible.

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I have wanted to orbit asteroids, for like... EVER.

Edited by Lo Var Lachland

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This is a FAQ. I'm too lazy to look up previous answers, but IIRC:

a) in KSP things are either movable, or they have gravity. For some reason or other it would require a major code overhaul to change this.

b) our asteroids are really really small and lightweight. Your pulse, through the soles of your shoes, would suffice to send you on a escape trajectory. It's just not worthwhile to give them gravity because there would be no noticable effect on anything.

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To bad I was hoping to do a lander orbiter mission

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Let's calculate the smallest class E asteroid gravity

by the kspwiki and game description, class E asteroid no less then 18m in radius and the minimum mass is 854 ton

so the gravity=G M/ r2

=(6.67x10-11) x (854 x 1000)/182

=0.0000001758 m/s2

Gilly gravity is 0.049, it already need to land it like docking, asteroid gravity is total negligible

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Im not really sure if it would be usefull, every small movement could change your orbit alot.

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It was just an idea thanks for all the input I was hoping it was possible but sorry if I wasted anyone's time

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If you want to land on an asteroid, just go to gilly.  or bop.  But somebody should make a mod where there are a bunch of resized gilly and bop copies around the sun.

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On 24/09/2016 at 6:25 AM, AlexTheNotSoGreat said:

All asteroids are considered parts to KSP, so adding gravity to asteroids in stock is impossible. However, procedural asteroid "planets" might be possible.

it's very disappointing to hear that. but i do think if asteroids turn into planets or stuff that would have gravity, the ksp folder will double in size. THERE ARE MORE ASTEROIDS THAN THERE ARE PLANETS!!

*i'm pretty sure there are

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5 hours ago, Buzz light fear said:

It was just an idea thanks for all the input I was hoping it was possible but sorry if I wasted anyone's time

Genuine suggestions like this are never a 'waste of time'.  Even if the ideas turn out to not be possible,  practical or viable we can still learn something from them, and maybe even sow the seeds for variations on the ideas that could work.

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How about putting some gilliteroids around dres just for baking rendezvous more difficult for the generated asteroids that would be fun and hard at the same time.

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I like the idea of having some tiny gilly or smaller sized asteroids around the sun on similar orbits to dres.  Also some around dres.

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On 26-9-2016 at 6:20 AM, Buzz light fear said:

How about putting some gilliteroids around dres just for baking rendezvous more difficult for the generated asteroids that would be fun and hard at the same time.

When I read your suggestion, I misread gilliteroids (asteroids like Gilly) for "glitteroids", and thought of these:

And I was immediately enthusiastic because what Dres really needs is more action and more attention. Maybe add some party lights too?

Edited by Magzimum
typos

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The core problem is:

Gravity would be too weak. Assuming that a Class E Asteroid has 3000 tons, and a diameter of 30 meters, the acceleration would be 0,00000089 m/s^2.

That means that "falling" from a height of 100m would take you 4 hours! How fun is that? Also, how would you "stick" to the ground without the Klaw? You'd bounce off of it due to the slightest touch.

And the biggest problem is actually the KSP physics accuracy. KSP uses double precision floating point numbers for storing position and momentum. This means, there are tiny little drifts/uncertainties in position/speed. Those don't matter too much when around a body like Kerbin, but when "gravitationally bound" to such a rock in space, 0.00001 m/s can be the difference between impact trajectory and escape velocity.

Basically, your orbits would be all over the place.

Try this out: go around a small object like Minmus or Gilly, then circularize the orbit *perfectly*, say 100.000m apo, 100.000m periapsis. Now watch how the Apoapsis/Periapsis flickers. These are the the physics inaccuracies.

The best way to land on such an asteroid is to basically "dock" with it, using your own propulsion, and you can do that with the current system just fine.

Sorry, but I don't think this is a good idea.

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Look, gravity or not, that is only a feature of a display on the map. In reality, there is no real boundary between spheres of influence. I actually count Earth's quasi satellites as extra moons, whose orbital periods are longer than a year. If you intercept the asteroid and burn retrograde at the closest encounter, you can consider yourself in an orbit.

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On 23.09.2016 at 10:25 PM, AlexTheNotSoGreat said:

All asteroids are considered parts to KSP, so adding gravity to asteroids in stock is impossible. However, procedural asteroid "planets" might be possible.

I wouldn't mind the docking port style attraction force within 100 meters from the surface. No need for genuine gravity that would affect orbits. I'd love if asteroids could attract each other, so you could form a clump of them.

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2 minutes ago, Sharpy said:

I wouldn't mind the docking port style attraction force within 100 meters from the surface. No need for genuine gravity that would affect orbits. I'd love if asteroids could attract each other, so you could form a clump of them.

If you want the real values depending on the mass, the game engine precision is not enough (notice that KSP is a *game* in a computer that has limitations). Collision physics would shove everything apart, and floating point errors would be more influental than gravity.

What you could of course do is make it super exaggerated, for example as strong as gilly's gravity. But that just seems very silly to me.

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1 minute ago, Kobymaru said:

If you want the real values depending on the mass, the game engine precision is not enough (notice that KSP is a *game* in a computer that has limitations). Collision physics would shove everything apart, and floating point errors would be more influental than gravity.

What you could of course do is make it super exaggerated, for example as strong as gilly's gravity. But that just seems very silly to me.

The gravity could be "exaggerated" to 1% of Gilly Then cheat with a weak autostrut once things touch the asteroid surface - something that is trivial to break but overcomes the rounding errors.

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On 9/24/2016 at 0:01 AM, Buzz light fear said:

To bad I was hoping to do a lander orbiter mission

For a lander mission, I just attached a small probe with mining arms to an E class asteroid with a grabbing arm to make it look like it landed.

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I don't actually see the big problem. It shouldn't be too difficult to throw a quick plugin that applies the gravity of an asteroid to all the parts in physics range. You could never be in its SOI, but that would be silly anyway.

What would be actually interesting would be to find a way to model the uneven gravity of the asteroids, but that's something I'll leave for @eggrobin and Principia.

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How would you even tell?  These asteroids are all so tiny the gravity is unnoticeable.  Even the gravioli doesn't have the decimal places to show it.

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On September 29, 2016 at 6:11 AM, Sharpy said:

I wouldn't mind the docking port style attraction force within 100 meters from the surface. No need for genuine gravity that would affect orbits. I'd love if asteroids could attract each other, so you could form a clump of them.

This could be problematic because what would it attract a docking port or all parts within the 100 m range though a clump of asteroids could turn into a small moon( that's no moon that's the Death Star) type scenario and it could destroy kerbin if it was large enough.

Edited by Buzz light fear
Not enough words

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I actually almost support adding an exaggerated "fake gravity" force to asteroids, but that has one pretty important limitation. Imagine you land a probe on an E-class without any claws or harpoons. Then you leave it there and do other missions. When you return after a year, the probe will be megameters away from the asteroid. Even though the two objects had zero relative velocity, they had different centers of mass and thus different patched conics trajectories. There can be no permanence on asteroid surfaces without a large amount of new code.

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