Trying to Recall a Couple of SF Short Story Titles

Watching a trailer for "The Martian" recently ("Help is only 140 million miles away") brought to mind a couple of SF short stories with a similar scenario, in that someone is alone in an isolated location and has to rely on their wits to survive (otherwise) certain death. I'd intended reading them again, but I can't remember the titles, and I've been through all of my SF anthologies and none of the titles match my recollection. (I thought that one of them was J.W.Campbell's "Who Goes There?", but I found that one fairly quickly, and it wasn't (one of them).)

Story 1: The protagonist is (perhaps) surveying some planet with an inhospitable atmosphere, and (maybe) has to stay in some sort of little pressurised dome when not out surveying (or whatever). Then something turns up outside and starts banging on the walls, trying to get in. There are no weapons at the station, the creature is obviously capable of smashing its way in long before any help can arrive, and it's invisible to boot. How does he survive?

Story 2: The protagonist is (perhaps) exploring some planet with an inhospitable environment (a desert of some sort IIRC), accompanied by a guardian robot (there's some friction with the indigenous inhabitants). A camp is set up and the robot is ordered to maintain a defensive perimeter while the surveyor (or whatever) goes out on a reconnaissance, and not to allow anyone else other than the surveyor back in to the camp. On returning, the robot refuses to allow him back in, citing insufficient proof of identity. Whatever method or argument the surveyor tries to employ to prove his identity is countered by the robot. All the food & water is inside the camp, and the heat of the day is becoming increasingly unbearable. How does he survive?

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"Your reality, sir, is lies and balderdash and I'm delighted to say that I have no grasp of it whatsoever."