Isn't it weird that you can't land on asteroids, but Gilly, a captured asteroid, can be landed on?

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Posted (edited)

I understand that you can't land on smaller asteroids, but what about large asteroids the size of Gilly? (if that is even possible) Why can't you land on those? Squad, I demand answers

Edited by Nicodo123
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Posted (edited)

"Why" as in "What is the mechanical difference in how the game implements them?" or "Why" as in "What was the reason for choosing the implementation that has this limitation"?

I can answer the first, but the second is harder as that requires dev insider knowledge.

The mechanical difference is that Gilly, being a moon, is modeled as a kind of CelestialBody, while asteroids are a type of Vessel, much like flags are a type of Vessel and Kerbals floating in their EVA suits are a type of Vessel.

The game does not calculate the effects of a vessel pulling on another vessel due to gravity, since most of the time a vessel's mass is so small that the effect isn't worth the computing time it would take to bother. Also, when you go into time-warp mode, the game doesn't *really* use Newtonian gravity from a celestial body to pull on the ship anymore, it instead just uses Kepler's ellipse formulas to decide where along the orbit path the vessel would be at time=t.  To do that in the stock game model requires that the body you are orbiting be your sphere of influence center point.

So that answers the first kind of "why".  As to the second kind of "why", now I have to speculate about what was in the dev's heads.  But I'll do that.  I just want to throw the caveat that at this point I'm trying to read their minds and this is not definitive:    So here goes: To do gravity with asteroids using the stock system, those asteroids would all have to be modeled as tiny planets with their own little spheres of influence.  The sphere of influence model really breaks down at that point, as you have to be SUPER close to the asteroid before it's gravity is strong enough to treat it like its own little pocket reference frame that ignores perturbations from the sun.  I suspect they didn't bother because it's an organizational mess to have that many asteroids being modeled as planetary bodies instead of as vessels, especially when for the smaller ones their spheres of influence wouldn't even be above their ground altitude.  Imagine if it treated them as planets what the map view would look like with all those little orbit lines.  I think before it becomes even possible to do it well, the game would first have to leave behind the sphere of influence model and use an N-body model like Principia mod does.  And a change like that is *massive* and breaks some other parts of how the game is meant to be simple for players.

Edited by Dunbaratu
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Nothing weird about it. Gilly is only an "asteroid" in flavor text, but in terms of KSP game mechanics it is a moon.

KSP Moon: It has gravity and you can land on it. You can't change the orbit no matter how much thrust you use; it's "on rails".

KSP Asteroid: A free-floating object that you can redirect.

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28 minutes ago, Nicodo123 said:

I understand that you can't land on smaller asteroids, but what about large asteroids the size of Gilly? (if that is even possible) Why can't you land on those? Squad, I demand answers

The celestial bodies in KSP (ie, moons, planets and the Sun) are 'on rails' in terms of physics, meaning that no matter how long you push, you won't be able to shift them. Asteroids and comets are technically parts rather than celestial bodies to enable grabbing them and pushing them around, meaning that they have no gravity. And you don't really 'land' on something with no gravity, it's more like docking.

Also, none of the asteroid or comet sizes are anywhere near Gilly's size.

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On Phobos you have same problems.

Especially since it's at the Roche limit.

Maybe, Gilly, too. We don't know its geology.

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I'm sure you used to be able to land on asteroids and mine them, have they changed it now then? Why?

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1 minute ago, FruitGoose said:

I'm sure you used to be able to land on asteroids and mine them, have they changed it now then? Why?

Nothing changed. You can rendezvous with them and dock with a claw and mine away. You could never actually land on them.

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1 minute ago, Dafni said:

Nothing changed. You can rendezvous with them and dock with a claw and mine away. You could never actually land on them.

Ah ok, so I thought I was landing but actually I was just grabbing.

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2 hours ago, Nicodo123 said:

I understand that you can't land on smaller asteroids, but what about large asteroids the size of Gilly? (if that is even possible) Why can't you land on those? Squad, I demand answers

If those asteroids had gravity you wouldn't be able to tell anyway it would be so weak.

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