18 June 2018

Technical Errors in "The Martian"

Andy Weir's The Martian is one of the most technically accurate science fiction stories of all time, although it's not perfect.  I just re-watched the excellent movie, which followed the book unusually well.  This critique is based on the movie:

Martian atmosphere is about 1/10th that of earth.  The wind would not carry all that much energy, even if it's blowing 200mph, and it's hard to imagine it knocking over the MAV or carrying enough sand that the sand might do it.  The pictures of dust devils taken by the rovers are scrawny little things.  It is plausible that it might cause flight in lightweight things that aren't fastened down properly, such as satellite dishes, so the incident that seems to have killed Watney is remotely possible, but the crew would have simply hunkered down and ridden it out.

The Aries 4 MAV is already on Mars, 4 years ahead of its use.  Mission planners expect it to still be standing when the Aries 4 mission arrives, despite frequent sandstorms that apparently can knock a MAV over?

It is inconceivable that a month long surface mission wouldn't have several redundant transceivers that could quickly reestablish communication between a marooned spaceman and earth, even if the primary went back into space with the rest of the crew.  For example, I'd think each rover would have had a high gain antenna analogous to the one on Pathfinder--about a foot in diameter: a phased array with relatively low bandwidth and only needs to be aimed in the right general direction to obtain maximum gain.  Not quite enough bandwidth for SDTV video, adequate for voice, and more than adequate for TTY and still photography.

It doesn't make much sense to have a specialist botanist on an early Mars exploration mission.  A different specialty scientist who happened to have a background in botany, perhaps, but not a specialist.   Had I been in Andy Weir's place, I'd have had Watney have been a farm boy who grew up to be a scientist (geologist perhaps?) and astronaut.  Growing potatoes in martian soil and human manure is pretty basic farm stuff.   I'm pretty sure I could do it and I'm not a farm boy or botanist at all.

Watney manages to keep his potato harvest healthy for over a year after the breach, in the same atmosphere he's living in.  It's probably impossible to keep bacteria and fungus from his own body from infecting them.   I can't keep potatoes for more than a few months, unless I freeze them.    The originals from earth probably survived this way too: vacuum packed and frozen.  He'd have protected his harvest exactly this way, and they would have survived the HAB breach, and he could have started up his garden again.

The HAB is soft skinned.  This is plausible as a covering for non-human stuff and even short term habitation, but unless there is some sort of magic radiation shielding developed between now and then, totally implausible for a month long habitation.  The astronauts might survive, but probably not for long enough to make it home.  I think the only real answer is to put the dwelling underground.

The same point holds for the Hermes interplanetary ship.  They got a lot right for the Hermes design, but there's no evident shielding, which should probably be ten feet thick or more around crew areas.

A great deal of space on the Hermes is given to human-occupied areas in microgravity.  I would doubt there would be many--airlocks and docking berths--but you wouldn't expect the astronauts to need to go through them very often.

The calculations Rich Purnell needs to solve to work out the maneuver are mathematical and demand high precision, but are not especially complex.  He wouldn't need a supercomputer to solve them.  The laptop on his desk would be ample.  (had he been doing it in 1966, he might have needed a supercomputer, but the PC I'm using to type this is about 300 times faster than a CDC 6600, the fastest machine of 1966).   Even if he did need a supercomputer for some reason, he wouldn't have needed to leave his office to do it.  (that said: I met an "Orbits" guy when I worked at Lockheed Missiles and Space.  The eccentric Rich Purnell character is totally plausible.)

The MAVs (both Aries 3 and 4) are entered through an airlock in the middle of the floor.  Underneath that floor is the second stage of the ascent rocket and underneath that is the first stage.   Wrong.  The astronauts would climb up the MAV on the outside and enter through a door in the side.

When Watney enters the MAV with his EVA suit on, he enters through this same airlock door, and closes and fastens it.  It is obviously a big heavy thing.   I'd think it'd have been among the first things to be tossed overboard.

The nose cone is shown sliding right past the MAVs attitude control jets.  Watney is going to need those.  He'd have figured out some way to guarantee not breaking them.

I don't understand why they needed to blow the airlock door.  They can override other safeties, why not that one?   It does make a fun plot element though.

We see personal laptop computers from Commander Lewis, Johansen and Watney, and we can be sure the others left theirs behind too.  Why is it that only Lewis has recorded music on hers?


addenda:
Water has recently been discovered on Mars, trapped in rocks, plentiful and reasonably easy to obtain.  This spoils one of the central plot elements, although Weir couldn't have known that when he wrote the book.

I read Weir's latest, Artemis.  It's almost as good as The Martian.  

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