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How come the MAV capsule has a heat shield, is it also the Earth lander? Also, did anybody else notice: - the Hermes thrusting toward Earth when they said they were in the braking burn (before the Purnell maneuver) - during Watney's MAV ascent, a screw floating by his face (as in zero G) while still under acceleration with the engines firing vessbot fucked around with this message at 08:32 on Oct 12, 2015 |
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Oct 12, 2015 04:39
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| # ¿ Apr 29, 2024 09:45 |
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bawfuls posted:That wasn't a heat shield on the top of the MAV quote:Hermes accelerated towards Earth so that they would be going faster when slingshotted around. The Hermes had an ion engine so it works best when thrusting over a long time. That is the Purnell maneuver itself, and would not be happening before they decided to perform it. They should have been thrusting away from Earth so as to slow down, and they said as much in the movie...Just didn't show it. Surely the shot was put there after whoever was responsible for accuracy was finished checking things over. quote:I don't think the screws started floating around until after the MAV engines were spent. They did, there was a shot of a single screw floating by. After engine cut out, there were a whole lot more. vessbot fucked around with this message at 08:48 on Oct 12, 2015 |
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Oct 12, 2015 08:43
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I agree that Purnell is unnecessary and out of place because everyone would have known about the slingshot possibility from the word go. After all, there are only 2 main options, both immediately obvious: Hermes, or the Chinese ship. Everything else is a consequence or further detail of those, to be explored. (Whether there is or isn't enough delta v, how much it would prolong the mission, risk factors, etc.) I could see why they needed the Purnell character as a device to explain it to the audience, but the way he introduced it to the chief of NASA was painfully cringeworthy. They could have handled it, for example, like the real-life story of John Houbolt and LOR, where everyone knew about the maneuver but he championed it. And it was complete with the drama of him risking his reputation by going around everybody and making his pivotal bid straight to the top.
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Oct 13, 2015 06:26
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old dog child posted:The MAV had to land on Mars, vessbot. I'm not taking about the base of the entire stack, but the base of the capsule (the cone-shaped last stage that was left over when all engines stopped firing). That was not exposed for the Mars landing.
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Oct 13, 2015 06:31
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JohnSherman posted:Christ you must be awful to watch movies with. Part of the enjoyment of this sub-genre of sci-fi is realism as an end in and of itself. An egregious mistake in physics can deter from this goal and thus take away from the enjoyment, in a way that wouldn't happen for the same viewer with, say, Star Wars. For a different viewer who doesn't care about that, it may "work just fine" as you say.
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Oct 29, 2015 01:34
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Jerusalem posted:I think somebody mentioned earlier in the thread that in the book (which I haven't read, which I need to rectify) Watney actually makes a point of collecting soil samples along the entire trip because it's a (hopefully) once in a lifetime chance to get samples from across a 3200km stretch of Martian landscape. That's extremely bizarre, considering the absurd lengths they went to in stripping as much weight as they could from the MAV, and still didn't get all the DV they needed. They even (in the movie) specially addressed the weight allotment for soil samples as a "gimme" to obviously omit.
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Nov 3, 2015 03:05
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Ahhh... OK.
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Nov 3, 2015 03:15
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babua posted:When he goes into space he's wearing an EVA (extra-vehicular activity) suit, which has to be a lot sturdier and bigger than the planetside suit, because it has to withstand the pressure difference between the inside of the suit (1 atm) and vacuum (0 atm). It also needs to house systems that take care of storing the excess body heat temporarily, since you can't just cool off with air (like you could on Mars), since the suit is a completely closed system and can't lose heat to the outside. Mars' atmosphere is about half of a percent of the pressure of Earth's, so it's practically a vacuum. So that can't explain the difference in the suits. I like to think of it as being that the surface suit needs to be comfortable and mobile for daily usage and quick donning for a month, and they are able to achieve that with a super duper advanced design... which also came with a super duper advanced price tag, so they stuck with the old one on the Hermes, where they were there only for contingencies anyway. Plus for something needed for emergencies, it's a good idea to have a known quality instead of the bleeding edge tech. Kind of like modern jet cockpits that have more flat panel displays than an Apple store, but still have a mechanical gyro in case everything goes dark. (As an aside, space suits run about 1/3 atm) vessbot fucked around with this message at 08:54 on Nov 9, 2015 |
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Nov 9, 2015 08:45
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