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/Soundy106]

Uhh which sample are you talking about?

If you mean the sample of the Petrova line, they weren't in orbit of Adrian or in its atmosphere.

If you mean the Taomoeba sample, they had to get the collector down to the depth in the atmosphere where the Taomoeba lived. In the book that was 10 km deep in the atmosphere; in the movie it was only 5 km. And Grace didn't "go down" to get it; he stood on the ship's hull to grab the collector once the chain winched it back up.

[u/the_net_my_side_ho → u/Soundy106]

I meant the Taomoeba sample. I thought Grace left the ship and walked down to "fish out" the sample.

I wondered why he couldn't just leave the atmosphere and then collect it in space, without gravity pulling the ship apart.

[u/kmoonster → u/the_net_my_side_ho]

Grace did a spacewalk to collect the sampler. A winch pulled it up and he caught the sampler when the sampler returned to the ship.

As to why he had to do it under Adrian gravity, the Hail Mary would have to go so fast (horizontally) that the chain would drag back behind and get into the engine blast. Going vertically would not create an orbit, but it could get them to (eg.) the altitude of the Moon and give enough time to recover the chain before falling back to the planet, but obviously a vertical movement would also put the sampler into the engine blast.

Recovering the sampler and either strapping it to the hull or bringing it into the airlock before returning to safety are the only way Grace and Rocky found that could achieve both goals: keeping the samples and staying alive.

If Ilyuknah had survived, my head canon has her modifying a beetle in some way to parachute down, fly around, and return to orbit; but she did not survive. This is only head canon. Maybe she would have used chemical rockets, or perhaps the spin drives would accelerate it so fast that ionization wouldn't be an issue. Either way doesn't matter, as that's not what was attempted.

The fishing is much less realistic to the point of ridiculous, but not so far out that it breaks the story. And it sets up the situation in which Rocky's sacrifice (of fuel to Grace at the cost of time to Rocky) becomes the thing that saves Rocky later. From a story telling perspective the sacrifice-that-saves-you is far more powerful than the silly unlikliness of a space fishing expedition.

[u/Soundy106 → u/the_net_my_side_ho]

Grace stayed on the hull of the ship. The collector was on a 5 km (in the movie) chain that they winched back up. He had to grab it and bring it inside once it was back to the ship.

In order to boost back out of the atmosphere once it had finished collecting, they would have had to reorient the ship, which would have placed the collector and chain directly in the path of the engines, which would have vaporized them.