Some items:
1) My favorite part was Kivelsen mentioned that she "wanted to make a big nose; the biggest noise" and as it turns out, she did. She made the strongest transmission ever known by man. For me, it didn't matter what happened to her after that. She had completed her lifelong quest, even if she didn't realize it.
2) I was skeptical about the reality/unreality of the Voice of Io until the crystalline bridge, and even after that, there was just enough of a shred of doubt. If you've never been on hallucinogenic drugs, or have never gotten so tired/hot/cold/hungry that you start to hallucinate, it might seem impossible. But the brain is weird, and can manifest hallucinations as coping mechanisms in very odd ways.
3) Hols could not have saved Martha. Generally speaking, a landing pod detaches from the orbiter, and descends to the surface, landing on struts. Given that the gravity of Io is very nearly the same as Luna, about 1/6 of Earth, I would imagine the landing would have been done in a very similar way. My only complaint about the design is that Io is known to be very unstable, and the landing pod probably would have compensated for this. Anyway, I digress. The pod, when ready to leave, launches off the surface and reconnects with the orbiter, and they head home. There's no way for the orbiter to land, and really no easy way to get more equipment down to the surface. Even if a drop could have been made, what good would that have done Kivelsen? Given her 8 more hours to suffer before a slow death?
4) Lastly, amazing narration and production. Just spot on all around. The voice work to get in the proper emotional state was exquisite and the radio sounds/voices were superb.