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Powered Descent
Jul 13, 2008

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The wheels on the rover have that same spiral thing going on as the wheels on Spirit and Opportunity. This makes me happy.



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Jul 13, 2008

We haven't had that spirit here since 1969.

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Nth Doctor posted:

What purpose does the spiral serve? At first glance, it looks like some sort of torsion spring mechanism that would only work one way.

I don't know if it serves a particular purpose at all; as far as I know the wheel is just a rigid structure. For all I know they picked that design purely because hey, it had to be shaped like something, and the spiral looked cool.

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Jul 13, 2008

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hmmxkrazee posted:

Quick book question:
Was Hermes going to go to Mars regardless whether or not the probe resupply on the Earth flyby was successful? I thought if that failed the rescue mission would just be cancelled. What was the point of the plan where the rest of the crew would commit suicide leaving Johannsen (?) to survive?


Disco!?


The "mutiny" was that they turned the ship away from the nominal trajectory. Once they did that, they COULDN'T brake into Earth orbit anymore, they were committed to an Earth flyby on their way back to Mars, no matter what. They were forcing NASA's hand to either send them a resupply probe full of food or let them all die. NASA had previously rejected this rescue option, even though it had a better chance of rescuing Watney, because it risked six lives instead of one. But now they had no choice but to go along with it and send the resupply probe. And if the resupply fails, the astronauts all die.

Powered Descent fucked around with this message at Sep 2, 2015 around 02:45

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Jul 13, 2008

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CLAM DOWN posted:

I loving loved the book, one of my most favourite reads in years

I enjoyed the hell out of the book too. You just have to keep in mind that it's a Man vs. Nature survival/adventure story, NOT a character drama. The characters are just deep enough to serve their purpose, and not a bit more. Not a single one of them (Watney included) has anything resembling a character arc (except MAYBE for what's-her-name who does the satellite imagery, who gets more confident as time goes by). Almost everyone maxes out at one or two character traits. (Watney is just about the only one who takes more than three or four words to sum up.)

But like I said, it's not supposed to be a character drama. If complex character interaction is what you like, you're going to be disappointed. But if you like creative solutions to plausible problems, you'll have a grand old time reading it.

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Jul 13, 2008

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Groovelord Neato posted:

it's that even in that situation a person of that intelligence/training/age would not be "snarking" like that. it's written like the person only knows how people talk from his favorite pop culture and/or net forums.

Yes, the book would have been more enjoyable if he'd limited his log entries to a terse, professional listing of the events and never allowed his personality to show through.

And besides, real-life astronauts would never ever act like total manchildren or use less-than-business-appropriate language among themselves, no-sir-re-bob.

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Jul 13, 2008

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Groovelord Neato posted:

you guys really don't understand when you link those things

Groovelord Neato posted:

i don't even know why you folks keep linking them

Um... how many of me do you think there are? How many times do you think "we" have linked those, here in this two-page thread?

But in any case, you're right, Watney does talk just like a present-day goony nerd. But he does so pretty realistically. (I work for a company whose name ends in dot-com, and Watney would fit in perfectly at the office.)

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Jul 13, 2008

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old dog child posted:

also I'd love to see the Aquaman one-liner after NASA realizes he's alive and wonders what he's thinking being stuck on Mars all alone

They already used it in the Right Stuff teaser, in very different circumstances than in the book:

https://www.youtube.com/watch?v=Wygmxzp6VzY

(Skip to 45 seconds if you're impatient.)

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Jul 13, 2008

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Erwin posted:

What bothers me is the offset part at the front. That would throw off the center of mass for when they blow the front airlock, unless they adjust the vector slightly but it seems like it's just there for aesthetics.

PMA, perhaps? They're used on the real-life ISS to connect different docking systems -- essentially great big "adapter plugs" for Station modules. There's one between the US segment and the Russian segment (which use VERY different docking and berthing mechanisms), and two more that were used for Shuttle dockings (and will be used soon for manned Dragon / Orion / Starliner dockings). I don't know the reason for the joggle, but they definitely have one.





Perhaps the front section needs to be more easily detachable, or was built by another country. (Or perhaps it was just a way for the moviemakers to add a bit of visual interest and keep it from being one long boring straight line.)

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Jul 13, 2008

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There was a recommendation in the spaceflight thread to see this in 3D, which is somehow the first I'd heard that it was a 3D show at all.

What's the hivemind of this thread think? Is the 3D worth it?

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Jul 13, 2008

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Zero One posted:

But how much did it really cost to save Watney?

It's not like he used any extra funds to survive on Mars. Anything he did on Mars was a cost already spent by NASA.

The actual cost of the rescue is just two things: The failed supply launch and the successful supply launch. Any rocket launch is expensive but with SpaceX already trying to bring launch costs way down how much could it cost in the future when manned Mars missions are happening?

You can also consider the staffing costs that NASA spends in overtime to work the problem. Not small but probably not huge either. Real NASA already did similar things to bring Apollo 13 home so no doubt they'd be willing to put in the hours again.

The biggest cost I see is the loss of the Ares IV mission. When Watney takes the MAV to escape he has doomed the next mission. So the biggest cost to save him is what NASA had already spent on Ares IV... whatever that was in future dollars. While a substantially bigger amount than the cost of staffer overtime and two small rocket launches they didn't need to get authorization for extra funds. I'm sure the Ares IV crew was more than happy to see their mission used to save their friend (and know that they would have been rescued if the same thing happened to them).

I'm sure it won't cost much to fix the explosion damage to the Hermes. It's not like that ship would be the most expensive single object ever constructed by humanity, or anything.

But seriously, this was a good flick. I did kind of miss how in-depth the book got on all the technical stuff, but they're making a Hollywood movie here and they really can't spare three hours for clever uses of chemistry and heat transfer.

Also, at all of you trying to find a Deep Symbolic Message any more complex than "perseverance and creativity are good" or "people can pull together for a good cause" or "spaceflight is cool".

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Jul 13, 2008

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CommanderApaul posted:

I thought the same thing when he was putting on his EVA suit. Looked like he was maybe inside the Ares IV hab?

What Ares IV hab? The MAV was the ONLY thing that had been landed there so far. This is explicit in the book, and also visible in the film in the long shot we get of the rover approaching the MAV -- I sure as hell didn't see anything else around, did you?

But yeah, I have no idea where he actually was supposed to be for the beard-shaving scene. I guess the MAV had a room in the landing stage or something.

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Jul 13, 2008

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MikeJF posted:

The whole thing was that they needed a heavy rocket. There were plenty of normal rockets hanging around. We launch about two a week. But to get an appreciable mass to Mars rapidly you'd need a heavy.

If we're nitpicking the movie, they used stock footage of present-day boosters for the launches from Earth. The first attempt at sending supplies (the one that blew up) was pretty clearly an Atlas V, a 541 or 551 variant I think. The Chinese booster looked like a Long March, probably a 2 or 3. Also, the launch they see on TV in the epilogue is obviously a Delta IV Heavy. These are all among the heaviest lifters available today, and perfectly capable of throwing something to Mars -- the Curiosity rover rode on an Atlas V, for example. They're also fairly common as boosters go, and there are usually several of them in the pipeline at any given time. But would they be capable of throwing something heavy enough during a not-very-good launch window to Mars? No idea. I guess it'd depend on the mass of the resupply probe and the exact orbital dynamics, and even the book didn't go into THAT much detail.

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Jul 13, 2008

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Nail Rat posted:

Of course, this also begs the question of how the hell they were able to rendezvous with it when they were supposedly traveling at an extremely high velocity.

The big booster brought the probe up to the same velocity as the ship.

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Jul 13, 2008

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Dr. Stab posted:

Though, thinking about the rescue plan, why didn't they just over burn on their budget to make the intercept with the mav and then do the atmosphere trick later on to make intercept with earth rather than do everything all at once by the seat of their pants?

Yeah, that was a lot clearer in the book. Those maneuvering jets were the highest-thrust engines they had -- their main engine was an electric thruster with a teeny tiny force but which could run basically forever. It's made for big slow accelerations lasting months. Great for going between planets, useless for sudden moves. Hence the maneuvering jets. But even using 80% of the fuel for those jets, they could still only change their angle of flight just enough to intercept the MAV after coasting on that new course for forty minutes (or whatever it was). So now they would pass by closely enough, but still with way too much speed. The other 20% of their maneuvering fuel wouldn't have been anywhere near enough to slow them down for a proper rendezvous. What they needed was a big sudden push to slow them down right before rendezvous, none of their engines could do that, hence the unconventional seat-of-the-pants idea.

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Jul 13, 2008

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SavTargaryen posted:

So I've got a question that I'm pretty sure I'm just dumb and missed:

After he loses the potatoes but still had some left, why couldn't he just build a new farm? Was the actual HAV unit destroyed? For some reason I thought it was just the airlock, and he could set up a new farm with some potatoes. A bit of a gamble, maybe, but...

All the potatoes died when the hab breached and they were exposed to subarctic cold and near-vacuum for a day or so. Any potatoes he had would still be edible, but they sure wouldn't sprout anymore after that. (Also, the bacteria in the soil died too, but the movie doesn't call that out.)

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Jul 13, 2008

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Deteriorata posted:

Even then they would have a fully redundant backup system, just because they're NASA and everything is always maximally redundant whenever they design anything.

Yup, NASA would never put people on a complex system that required everything to work basically perfectly and had essentially no options for abort or escape if something went haywire at just the wrong time, and---



Oh. Oh yeah.

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Jul 13, 2008

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Panfilo posted:

-While two existing Martian probes are mentioned, its a little strange there aren't any others they sent out.given that Opportunity crapped out in 1997 I would assumed there were more. They mention fourteen pressupply probes each mission. Id assume one would survey the landing site before the mav arrived.

Yup, that's actually a bit of a plot hole -- in one of the little "life of a particular sheet of hab canvas" vignettes, it specifically says that the supply mission announced its successful landing to Earth. That radio would probably have been a lot easier to rig something up to than a decades-old busted probe. I suppose those radios might have been destroyed in the process of unpacking the probes, but that's kind of a stretch.

Panfilo posted:

-I'm surprised there was no contingency for stranded astronauts. Everything hinged on the mav working perfectly. If it tipped over,malfunctioned, etc six people would be trapped instead of just one.

During Apollo, everything depended on the LM ascent stage. If the ascent engine doesn't light, two astronauts die. Full stop.

Panfilo posted:

-Also surprised the Hermes was left vacant while the rest of the crew was on Mars.many if not all of the Apollo missions had a crew member stay on the spacecraft. This kept a human element onboard for emergencies.

During Apollo, the CM pilot had all sorts of jobs to do - mostly taking photos and turning experiments on and off. That's the sort of thing we'd have a computer do these days, and in fact the short-lived Project Constellation back-to-the-moon plan brought all the astronauts down to the surface, with no one but the computer minding the store on the orbiting mothership.

Panfilo posted:

Loitering in martian orbit, they could have rescued him much sooner.

How? Even if Watney had started modifying the rover on day one, it still would have taken months at least for him to reach the other MAV. The crew has limited food aboard the Hermes, and their launch window back to Earth is going to close sometime.

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Jul 13, 2008

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Macdeo Lurjtux posted:

I'm not sure why Dong Lover's character was even necessary. Using gravity wells to slingshot acceleration has been in NASA's repertoire since at least the 70s.

Computers can calculate orbits, even complex gravity assists, really easily these days. But they can't come up with an idea to do something no one had thought of -- in this case, resupply the Hermes en route and send it back to a Mars flyby ASAP instead of bringing it home to fit it out for a full rescue mission, as had been the plan before. It's the sort of thing that only an orbital dynamics engineer would have even thought of. And that's why the character is there. You need to think of an idea before you can calculate its orbital parameters, after all.

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Jul 13, 2008

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MikeJF posted:

I think his point was more that that'd be basically the first thing NASA thought of. They're all about slingshots.

So because they're aware of the concept of a gravity assist, they'd automatically and immediately think of an entire mission plan that's totally the opposite of the obvious one?

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Jul 13, 2008

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Deteriorata posted:

The first thing they would do is hold a meeting to discuss all their options. Getting Hermes back to Mars ASAP would be #1 on their list. While it's certainly possible that the idea of using a gravity assist would be overlooked, it seems rather unlikely.

There was more to the idea than "use a gravity assist". The Hermes was on its way home, with only enough supplies to last for the rest of the cruise back to Earth. It would be due for refurbishment and refueling so that it could be used at the next launch window for Ares 4, which was the obvious thing to build a rescue mission around. So getting it home was the plan, not sending it back to Mars ASAP.

A thing about gravity assists is they aren't available all the time. It's very common to need to wait years for the planets to line up just right for an assist that gets your probe where you need it to go. To find one that would work exactly when and where it was needed, and then realize that there was a way to build an entire mission mode around it that was just barely within the capabilities of no less than three spacecraft (Hermes, Taiyang Shen, MAV), was the clever bit.

Was the explanation of the gravity assist plan hammed up for the movie audience? Absolutely. But it's not at all unrealistic that nobody would have thought of the idea for a while.

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Jul 13, 2008

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TinTower posted:

Because of what happened to Airlock 1, basically. Messing with the pressure in a working airlock would be an incredibly bad idea.

Also, the airlocks got a LOT bigger for the movie. In the book, they're phone booth sized.

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Jul 13, 2008

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Deteriorata posted:

His process for catalytically decomposing the hydrazine released nitrogen gas and hydrogen gas. The hydrogen was then burned to make water. There was no need to decompose it, he could have just reacted it with oxygen directly.

We can rationalize that by saying that Watney wasn't a chemist. He was just kind of going on the half-knowledge he got from being Vogel's occasional lab assistant, and came up with a procedure that was more complex than it needed to be.

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Jul 13, 2008

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Simplex posted:

So something I just don't understand. They have to abandon the mission and evacuate Mars because a large storm is coming through with winds strong enough to possibly tip their escape vehicle over, which would leave all of them stranded on Mars. This is a possible contingency that everybody knew about. Watney eventually gets off of Mars by using the escape vehicle from a future Mars mission. It is kind of half-assed explained in the movie, NASA plans ahead really far in advance so they land the MAVs years into the future of when the manned missions are due to arrive. This makes absolutely no sense to me. If you know the escape vehicle is susceptible to getting blown over by a strong gust of wind, why would you land it years before you need it? I enjoyed the movie quite a bit overall, but that seems a pretty major plot hole with the entire premise.

I think the idea was that it was a freakishly powerful storm. Think of it like having a building that can stand up to a category 4 hurricane. There's always the possibility that a cat 5 will ruin your whole day, but chances are excellent that that won't happen in the next two years.

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Jul 13, 2008

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NotJustANumber99 posted:

Now, I wonder, it doesn't happen in the film, but in the book does he take those mpegs home on a USB stick or whatever? Because it kind of seems like he should as they surely represent the most valuable training/marketing/whatever material NASA will ever get out of this whole thing. Maybe the spaceship sees the updates when it reappears around Mars and auto down(up?)loads them?

In the book they're text in a computer, not video. (Which is pretty unsurprising. Video as the main format of a book is as awkward as a lot of text in a movie.) And I don't think it's ever really specified, but he could have pretty easily uploaded his logs once he got to the MAV, or kept a copy in his spacesuit during launch. Come to think of it, he writes an entry once he's aboard the Hermes, and doesn't mention that he's starting a whole new one, so presumably he still has it.

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Jul 13, 2008

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NotJustANumber99 posted:

I realise I'm annoyed by commander Lewis buggering off to save the day at the end.

She's already assigned everyone their roles and got it all figured out.

Then other fella, Beck I think, is, at a moment's notice, bouncing around outside at apparently a million miles an hour seemingly without a tether, handling a homemade bomb and gets back into the airlock to do his actual job, only to be met by his boss saying no, I'm not prepared to risk anyone else. Er? wtf?

So the commander does his job instead, which is basically just being a fishing hook but with the bonus of getting to be the person that grabs (is grabbed by) Watney. Its such a Captain Kirk ego nonsense.

Its no wonder she's not on the next mission. Fired.

For whatever it's worth, she doesn't do that in the book. For the movie I guess they figured the big hero moment should go to a character they've spent a little more time on than what's-his-Beck.

But speaking of book vs. movie endings... in the book, Watney says something like "If this was a movie, the entire crew would have met me at the airlock for high-fives." And sure enough, in the movie, they do exactly that.

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Jul 13, 2008

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NotJustANumber99 posted:

He appears to be the second most competent 'computers' nerd on the team.

Not necessarily. At the risk of making this the eleven billionth case of "it was clearer in the book", it was clearer in the book. At one point he wanted to override the environmental failsafes in the Hab computer, but he couldn't figure out how, so he had to trick it with an oxygen tank and a bunch of duct tape. And here's a line from his email to Johanssen:

Mark Watney posted:

Looking like that, why are you such a nerd? And you are, you know. I had to do some computer poo poo to get Pathfinder talking to the rover and oh my god. And I had NASA telling me what to do every step of the way.

Competent with the mission computers? Sure. An expert? Nope.

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