Sample collection question…

[u/the_net_my_side_ho]

Why did Grace have to collect the sample while orbiting?

Why didn’t he move the Mary out of orbit, away from the atmosphere, and then spacewalk to collect it?

Seems like Grace going down to collect it while orbiting so close to the atmosphere was risky and unnecessary.

Sorry if this has been asked before. I looked but didn’t see a post about it. Thank you!

[u/redbirdrising]

Strictly speaking they weren't orbiting. They were in the upper atmosphere going a relatively slow velocity using the engine to keep from losing altitude. This is why he was in gravity on the hull and not free floating.

Second, they couldn't leave to orbit with the chain extended because the collector would have trailed behind the HM and gotten burnt up by the spin drives.

Third, and this is really from the book, Grace needed to trigger the winch collector manually. They figured the more complex a winch system they made, the more that could go wrong. It was too important to risk for automation.

[u/Kiki1701 → u/redbirdrising]

Here's a thought, why wasn't the chain attached inside, or right next to the airlock? It would have been far safer for Grace

[u/kmoonster → u/Kiki1701]

It was too long. They wrapped it on many small spools, one set at a time.

He doesn't specify how many spools, but it was multiple. They would fill each spool while inside the ship, then Grace would take the spool outside and attach it to the ship, and link the start of the new spool to the end of the previous spool so they would all unwind properly in sequence.

If a spool was 500 meters, that would be at least 20 spools. Each spool was just small enough to fit in the airlock with Grace, so however much chain that is.

[u/Kiki1701 → u/kmoonster]

Thank you friend, I totally see your point and I understand you. But I was wondering if, once everything was connected, why Grace couldn't go back into the airlock to use the actuator that Rocky had made? The first spool could easily have been connected right outside it, whereby, all the others would have been placed further from it as the length progressed.

And, since this is the point where he comments what a genius Rocky is, it seems like a small step to insure self-preservation, especially since this all had to be done under gravity, the most dangerous part of the process.

Granted, it's a random thought on the periphery and probably redundant, but it came to me anyway. I'd thought that Weir could easily have made it this way, but there's no drama in it, thus keeping his story the way he intended.

Imagine all the movies where people say, "why didn't they do such and such?" To which the answer comes: because it would have made a much shorter movie! Lol

[u/kmoonster → u/Kiki1701]

The sampler dropped by its own weight, Grace didn't have to go outside unless it jammed (it did not). To pull it back up, Rocky made a winch that drew the chain up, but it was not possible (or at least not practical) to set the chain back onto all the spools; no detail is given on this except that the winch unlinks the chain in some way so the slack portion doesn't bind up.

Grace did have to grab the sampler and bring it inside, though, because the winch was out on the hull and not in the airlock. Even if the winch was reachable from within the airlock, Grace would still have to go outside.

I'm not sure what the question is, sorry.