2 things:-
1) With a rocket-assisted landing there's no way to stop this happening. You can't somehow send down a preparation crew and roll out some thermal blankets and insulating foam, and then mop it all up afterwards. Whatewver happens, will and has happened.
2) Don't underestimate the tenacity of ice.
Permafrost is like concrete. It blunts jackhammers, it laughs at blowtorches. A nuclear detonation or meteor impact will rapidly find hard bottom and be repelled back out as a shock wave.
There will be some good stuff down there. Let's be patient and see what turns up.
(There's a small but annoying chance that the ground will be frozen so hard that the scoop won't even be able to dig into it. Let's see what happens, eh?)