May 15, 2020 Update: These two achievements are now both finally obtainable! Disregard the following postIt appears this game currently has two unobtainable achievements, as the achievement list is the same as the Steam release, however not all content from the Steam version was ported over onto Xbox.
Explorer has you visiting all 6 of the game's planets and moons (Earth, the Moon, Mars, Europa, Titan, and "Alien"), but the last 3 are nonexistent on Xbox and only available to Steam players. Have tried several different methods of getting this achievement with just the 3 that are available, including loading a fresh game spawning on each planet/the moon, and even using admin tools to teleport to each location with no luck.
Death Wish requires you to spend 5 hours in Armageddon mode, a mode which meteor showers are constantly raining down on you, though this option is not available in Xbox's game settings when you start a new world. On Steam this is found under the "environment hostility" settings, but is also nonexistent on Xbox and the only two options you are given are safe & normal.
I have submitted a bug report for both achievements over on the Keen's support page, and have it linked below if anyone wants to check it out and upvote my report. Doing so will hopefully bring more attention to these issues and get the developers to look into this and put out a fix quickly. I will also continue to update this thread if/when I hear more back from them.
https://support.keenswh.com/spaceengineers/public_test_xbox/...