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Stowaway (Netflix): meh
The premise of Stowaway, a new movie from Netflix, as shown in the teasers: a crew of three leaves for a two-year mission to Mars, and after departure discover an injured worker from the launch pad onboard -- not really a stowaway in that he didn't plan for this, but there he is. But the safety margins don't account for an extra person.
I immediately thought of "The Cold Equations", a classic SF short story. It seemed clear that there could not be a happy ending, but I was curious which of the several possible outcomes we'd get. IMO they chose the wrong one.
Spoilers below.
The trio consists of the captain (Marina) and two younger researchers who've gotten their Mars-dependent research projects approved. Zoe is a medical researcher and David is a biologist trying to cultivate algae on Mars. The accidental fourth is Michael, who's designed to tug all the right heartstrings: pursuing an engineering degree while working to support his younger sister (no other family), hard worker, personable.
Marina is a seasoned captain and is on what's planned to be her last mission. In case you're wondering how a seasoned captain could miss the extra weight, especially when they've been given very small weight allowances for personal effects, it's addressed plausibly.
Zoe is caring and compassionate. We also see her medical knowledge play important roles twice early on -- treating Michael's critical injuries from the accident that caused him to be unconscious on the ship during takeoff, and also treating the captain's broken arm.
David, on the other hand, is so focused on his research that when the captain asks him to activate some of his algae samples to filter carbon dioxide from their air so they don't all die, he objects because it will waste years of his work. Yes, that sucks and I'd expect him to be upset, and he's not career space crew with the corresponding training, but it still left me disliking him.
David lost more points with me by trying to take matters into his own hands to get rid of Michael. Presumably even those who aren't career space crew, as condition of being on the ship, have been thoroughly drilled in things like chain of command. It's a short chain in this case.
There are setbacks and the crew tries everything they can to mitigate them, but it's clear to all that four people will not arrive alive on Mars. There's some sort of Plot Reason that I didn't understand about why they can't turn back, but they can't. So they have to deal with this and obviously there is not going to be a happy ending for all four of them.
There could have been a redemption arc where David steps up. This is the outcome I was hoping for. Instead, we arguably got the worst possible outcome, from a dispassionate perspective of trying to maximize survival chances. If it wasn't going to be David, there was another obvious candidate other than what happened, and it's not even as cold as those equations.
(I'm not trying to completely spoil it here even behind a spoiler warning, but I make no promises about what happens in comments.)
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He's not obviously a genius. I mean, this isn't Sheldon Cooper class. We don't get a ton of character depth for any of them, but I felt we got more for Zoe and Michael than for the other two.
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"Not Sheldon Cooper class" is a relief, hehehe.
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(Anonymous) 2021-04-25 10:00 am (UTC)(link)I haven't watched Stowaway, but depending on the drive system of the spacecraft, there's a very plausible reason why they couldn't just turn around and go back home: they don't have the fuel to do so. Any plausible Mars mission using something resembling current technology will very likely involve either (a) a good burn at the beginning of the mission, followed by a long coast, followed by another burn for Mars orbital insertion, using chemical rockets, very similar to how Apollo got us to the Moon; or (b) a more or less continuous "burn", using an ion drive, with a flip-over about midcourse so that the velocities match on arrival. Ion drives are nice because they require very little reaction mass and can be (read: are) powered electrically, but they draw a lot of power and produce very little thrust, leading to a very low rate of acceleration, which makes them largely unsuitable for manned spaceflight and utterly useless for a surface launch. Chemical rockets offer much greater thrust, but require gobs of fuel and reaction mass. (That external tank on the Space Shuttle, which was about as big as the Orbiter itself? They emptied that in about ten minutes flat, and it only got the Shuttle into a fairly low Earth orbit. Or compare the size of the Apollo command module and lunar module ascent stage/cockpit, which together formed the habitable volume of the spacecraft, to the size of the entire Saturn V stack; the difference isn't only fuel, but fuel is a big part of the difference.)
Thus, particularly if the mission uses chemical rockets, it's quite possible that after the initial trans-Mars injection burn is complete, they are committed to the trip simply because they don't have the fuel to turn around and get back home. For the planned trip home, in-situ refueling on Mars is a very real possibility; even though Mars has a very thin atmosphere, there's still a good amount of carbon dioxide available, and carbon (properly processed) plus oxygen makes a quite passable rocket fuel combination.
The harder part to explain away is that the additional mass would throw off every calculation involved in changing the orbit of the spacecraft to begin with, so unless they adjusted for the unexpected mass without questioning why they needed to do so, they would miss Mars in the first place.
/Your Friendly Neighborhood Anonymous Internet Canine
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Are you referring to the short story or to one of the dramatizations of it?
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Ah, that makes sense -- thanks! I knew the "lots of fuel and locked-in trajectory" is what they used with the Apollo missions, which is why 13 was so dicey -- it's not like the astronauts on board could just adjust a heading at the controls. I had assumed that the approach would be less feasible for a long journey; you can calculate a trajectory and plan to fire and coast, but if anything goes wrong you're stuck, and it seems like there'd be more opportunity for things to go wrong with an eight-month trip than a four-day one. On the other hand, there might not be a choice, for the reasons you gave. As for Stowaway, there was a big many-Gs long blast at launch and no particular evidence of electric-powered ion drives, so that's probably it.
Their initial trajectory at launch was slightly off (they showed a screen onboard of planned vs actual). The captain noted it. Mission control told her the variation was within expected norms of fluctuation, so they didn't abort then. Of course, nobody yet knew the cause of it being off. They spent days with that extra mass on board, so you raise a good point: do they all die anyway because they're going to miss Mars?
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(Anonymous) 2021-04-25 05:43 pm (UTC)(link)Actually, the Apollo 13 crew had on-board burn data for a burn at mission elapsed time 60 hours (IIRC) that would have got them home early, which would have been usable per se since the explosion occurred at MET about 56 hours, leaving them a few hours to come to the conclusion that the mission was unsalvageable. (Such pre-computed burn data would be useful, for example, in case of a loss of communication with the ground.) The problem on 13 was exacerbated by the fact that no one knew the status of the big engine on the service module (the SPS engine), which through a lucky break left them with just the lunar module's descent engine -- which wasn't powerful enough for an early abort, plus the LM wasn't meant to be flown in that configuration and they wanted to retain the service module to protect the command module's heat shield. So all in all, they had to get the combined SM/CM/LM spacecraft back onto a free return trajectory around the Moon instead, which required a much smaller mid-course correction; adding a few days to the journey compared to an immediate turn-around abort, but also ensuring that whatever else happened, they would have been, as Lovell said in a documentary I watched some time in the mid-1990s, on a course that "intersected the Earth in some manner". The burn made on 13 after going around the Moon was more to pick up speed and get the crew home sooner than to get them onto a proper trajectory. The Apollo 13 movie is actually very close to reality in this regard.
If in Stowaway the launch was from the surface of the Earth, it would almost certainly be by chemical rocket propulsion, which adds up nicely with multiple G. (For comparison, the Space Shuttle crew experienced up to about 3-3.5 G during launch, which isn't terrible. I've sat in a small airplane doing 2 G turns, and while things get heavier, that's definitely not immobilizing even without any particular training.) Ion drives, because of their very low thrust, really are only usable once you're already in space. (1 G is about 10 N. Present-day ion drives have thrust in the low mN range, so you might be looking at 0.001 G or thereabouts. From a crew perspective, they might about as well be in a freefall environment.)
Some variance is unavoidable when doing orbital maneuvers, so no one is going to plan a mission such that everything has to work out perfectly for the spacecraft to end up on the correct trajectory. (Apollo also did a few mid-course corrections on each mission; while the lion's share of the trip to the Moon and back was coast, they didn't rely entirely on the trans-lunar and trans-Earth injection burns to be accurate.) Any mission would have some excess fuel and reaction mass so that they can compensate for small errors; but needing to turn around after completing a trans-Mars injection is not compensating for a small error by any means. Realizing after the trans-Mars injection burn is complete that you need to go back would be about equally problematic from a course correction point of view regardless of whether it's minutes, hours, days, or months after TMI. Granted, the sooner you realize that something is very wrong, the longer you can afford the course correction to require to get you to where you want to go, whether that is onto a correct transfer orbit or back to Earth.
In real life, I suspect that the safest course of action for a crewed Mars mission would be to make the initial burn to go from Earth orbit into a transfer orbit toward Mars put the spacecraft on a free-return trajectory around Mars, with a small mid-course correction at some point (quite possibly very late) to leave the free return trajectory and commit to Mars orbital insertion. It would take some fairly complex orbital calculations, and it might limit the available launch windows, but it's not something we wouldn't know how to do. The 2000 movie Mission to Mars had it the other way around; their original trajectory would have overshot Mars, and for different reasons, they botched the Mars orbital insertion. Either works for drama, I guess, but in actual spaceflight one generally tries to avoid unnecessary drama. There's plenty enough risk to go around anyway.