Fridge Brilliance: At several key points, Sarah will give you hints on certain actions to take. These actions aren't necessary to complete the game, however. The hints in question are: trying to break the glass when the body is trapped in the tube, commenting that perhaps she could warm up the man in the freezer, and thinking about how cold the fully assembled body looks. While from a Doylist perspective this could be taken as the game's attempt to avert Guide Dang It, from a Watsonian perspective, it's a sign that Sarah has genuinely earned her chance at redemption — it's possible to earn the Redemption ending if you do all or two of these actions. Also note that she warns you against clipping the wires in the Analyzer, which is the only action in the game that can lower your Karma Meter.
Fridge Logic: So Sarah's reward for atoning for her sins is... Spending eternity completely alone on a tiny island in the middle of an eternal ocean? And not even the whole island at that; it's too densely forested to even walk between the trees maybe 25 yards from the coast.
Judging by the ending cheesecake shot, she's doing quite well for herself. Set up a camp, a fishing line, and got that bikini from somewhere.
Or alternately, the trees seen when back up in the ship were so dense because the artefact could only project a small portion for our heroine to explore. There's no telling what the real beach at the end was like, though we do see her amongst some flora during the Fanservice credits.
It's better than the alternative endings...
I just assumed the escape pod had a tracking device, so she'd be rescued eventually. Given the fact that it seems that humanity has spread acoss the galaxy, you'd think this'd be a given.