Friday, July 6, 2018

The Phobos Experience, by Mary Robinette Kowal

★★★☆☆ Average

(Punchcard Punk; Lady Astronaut) The director of the Mars colony sends three people to investigate Phobos, which is apparently hollow. (7,140 words; Time: 23m)

Recommended By: πŸ‘RHorton.r+1 (Q&A)

"The Phobos Experience," by (edited by C.C. Finlay), appeared in issue 07-08|18, published on by .

Mini-Review (click to view--possible spoilers)

Review: 2018.364 (A Word for Authors)

Pro: The mission is accomplished, the pirates are routed, and the general’s plot is defeated.

Con: The three astronauts were way too confident that no one could overhear their radio conversation.

Darlene’s secrecy about her vertigo endangered everyone else. It’s annoying that she suffers no consequences.

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3 comments (may contain spoilers):

  1. This was really grating, for two reasons.

    One was the vertigo. Either the flight surgeon is completely incompetent, or Darlene lies about it in order to get cleared: someone who is experiencing vertigo while looking down at a sheet of paper is having a severe bout. (I've had a few; it's not fun.) And after the usual eye-rolling claptrap about how you have to have a human navigator on board because computers just can't match a human, she's completely incapacitated by her vertigo and is thus useless anyway, although in that part of the story it doesn't matter anyway because none of them can see because of the dust.

    That brings up the second reason: the astrophysics is terrible. The reason throwing a handful of dust into the air produces a different result than a handful of gravel is because the ratio of pressure to gravitational forces is vastly larger for the former than the latter. Take away the atmosphere, and there is no difference in the way they behave. The thrust from their ship is not going to raise clouds of dust that block the ground from view. While it will certainly disturb the layer of dust on the surface, most of that will be blown laterally (because that's how the exhaust will escape from underneath the lander) and follow ballistic trajectories. (Weirdly, Kowal gets this right at one point in the story, where she talks about the dust following inertial trajectories and settling back on the ground.)

    And the whole bit about the astronauts sinking into the three-foot deep dust layer on the surface is also just head-bangingly wrong. Try punching your hand into the top of an open bag of flour and see where that gets you. (Not hard! Your fist isn't going very far.) The only way to get a fluffy dust layer is to have material with a large surface area to mass ratio and support it with air pressure, but planetary dust layers are nothing like that.

    This is an idea that Kowal, ironically, might have gotten from her research for these stories. Back in the early 60s, a physicist at Cornell named Thomas Gold got NASA to waste an enormous amount of time worrying over his claim that the lunar surface was covered with a layer of dust a kilometer deep, and that any spacecraft that landed on it would simply sink out of sight. Apparently NASA didn't have anyone on staff who knew any more physics than Gold. It wouldn't have mattered if the surface of the moon was a kilometer deep in feathers*, you were in no danger of sinking into it.

    Gold seems to have made a career out of being spectacularly wrong; in the 1980s he claimed that there were huge amounts of methane located in the Earth's crust. The geophysical community was not impressed.

    *Slight exaggeration for rhetorical effect; feathers have tensile strength which would keep them from compacting near the surface.

    1. I remember the worry. When the Surveyor probes landed, I remember reading how they'd put that worry to rest.

      But I also enjoyed reading "A Fall of Moondust," by Arthur C. Clarke, where he reduced the problem to a single area of the moon where this was a risk.

      Now that you point it out, yeah, regolith particles are so irregular it's impossible to imagine them slipping past each other enough to let you sink in. On the other hand, although you can't sink into flour, you certainly can drown in wheat.

    2. True, although I think the only way you can actually sink down into it is if it's in motion (as opposed to falling into a hollow and getting buried or having a mound collapse on you). Still a horrifying way to go.

      I also have fond memories of "A Fall of Moondust".