[civilian]

Eh, I've played KSP, an orbital rendezvous in LEO on your return isn't that hard. If you have enough precision and fuel leftover to start a safe decent, you have enough precision and fuel to dock with the ISS.

I'm surprised that we aren't equally worried about contaminating Enceladus with terran microbes.

[Crito]

If you are coming in fast from interplanetary space, you'll either need to aerobrake or burn a good deal of fuel to get yourself into LKO. While aerobraking from interplanetary space to put yourself into a nice orbit is easy enough in KSP, in real life things are much more difficult (just for starters, in KSP your station is probably at 0 degrees inclination unless you went out of your way to put it somewhere else...).

Get FAR, RSS, Deadly Rentry, put your space station somewhere around 50 degrees inclination, then try it with suitably small probe. The Stardust spacecraft was 300kg; the sample return capsule was 46kg and reentered at nearly 13km/s.

Just one full small kerbal RCS tank puts you at 250kg, so you'll need to nearly empty that just for starters...

[InclinedPlane]

KSP is intentionally a lot easier than actual Earth-based rocketry. Orbital velocities in KSP are much lower than in reality, and because the rocket equation is exponential that makes everything in KSP expenentially easier to do.

[mikeash]

You don't need any fuel to start a safe descent, except for a tiny amount for course corrections. The atmosphere does all the work.

[Steuard]

We're very worried about contaminating other worlds. But in this case, the plan (as I understand it) is to collect samples from the plumes of water that Enceladus shoots out into space, without ever landing on the surface.

[Hello71]

psst, kerbal is not a substitute for actual physics.

[Tuna-Fish]

However, it turns out we can introduce actual physics into kerbal. http://forum.kerbalspaceprogram.com/threads/68502-WIP-Princi... + real solar system + realism overhaul.