Need help modeling impact

[reptilelover1995]

Right now I'm in a course called Search for Extraterrestrial Life, and one of the things we're doing is trying to estimate the size an asteroid would need to be in order to vaporize all of Earth's oceans. I've come up with an approximate mass, but I'd like to use Universe Sandbox 2 to simulate the climactic effects of such an impact to see what would happen. Problem is I can't seem to get the simulator to do what I want.

I tried using the default simulation to launch the hypothetical asteroid at Earth, but I kept missing. I then slowed the time step down and was able to hit the earth but the impact was far too mild. I'm pretty sure of this because when I used the "Earth vs Asteroids" simulation, deleted all but one of the asteroids, and assigned it the estimated mass, the crater was many times larger and there were numerous smaller craters from the debris falling back to the surface. However, when I try to speed up the time step in that simulation the Earth starts to freeze over/cool, which obviously is a problem.

Could someone please tell me what I can do to get the impact I'm looking for and still have a good time step so I can see longer-term effects without waiting all night? Thanks in advance for any answers!

[codefantastic]

Climate and asteroids effect on it aren't modeled 100% yet. All I can say is mess with the speed of the asteroid.

[reptilelover1995]

Ah, well the problem is I need to be able to see whether or not the asteroid is able to evaporate the oceans, which would mean surface temps approaching 100C, but that would take a while and with the time step I can't seem to get that.

[Plutonium]

As far as I understand you have been using the general simulations. Try using Create menu then Collisions tab, choose any of presets, hit the edit icon (lower rlght corner of the thumbnail) and you will have everything you need to create the collision you want. But keep in mind that you won't have a Sun so climate will cool down faster.