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It's the same reason they tell you to put your oxygen mask on in a plane before you help others. You will pass out quite quickly, because your lungs change from an oxygen input system to an oxygen output system--your lungs work by osmosis. At 40,000 ft, you'll pass out in 15-20 seconds--whereas most people can hold your breath for 1-2 minutes (without training). Also keep in mind this is "useful consciousness", not death. You will be living, but unconscious, for a while longer. If the plane descends quickly enough, you'll simply wake up with no permanent effects.

What this means is that the prisoner could extend their life for 1-2 minutes by holding their breath. But eventually, they'll run out of oxygen either way, and it gets quite uncomfortable to hold your breath for an extended period of time due to the buildup of CO2 and lung reflexes.

You also wouldn't want to hold your breath during explosive decompression, because your lungs would be at risk of damage or rupture. See [2]. So either way, if you're at high altitude without oxygen or a suit, you're in serious trouble. Likewise if you're strapped to a table and people are just waiting for you to finally breathe and die.

Source:
[1] https://aviation.stackexchange...
(See the accepted answer there, although the FAA has updated their website).

[2] http://www.geoffreylandis.com/...

Your answer seems to be in conflict with your credentials. The provider of data should not be the interpreter of information. You state the facts as you know them and your confidence in those facts. If the best they can do is "the United States" then the logical reply is of course "the center of the US" with a radius of inclusion being the maximum distance reaching out from the center that could be included. What is done with that data is the responsibility of the interpreter and communicator of information derived from that data.

Regarding your points: First, the ship. You either have a rigid ship that stays upright until it won't, or you have a ship on gimbals with some "give" to it. Either way, there's going to be a literal tipping point and the amount of anticipated wind is the guide. Obviously they over-played the amount of atmosphere and thus the amount of wind on Mars, and clearly did so for dramatic affect. Accurate: no. Dramatically well played: yes.

The question of Whatney's survival was substitute narration, as already explained. As for freezing, his suit would have had to have not just an insulating effect but a heater just to be out during the -63C day.

Ruptured lungs is pretty much imploding. His capillaries would also rupture, starting with the ones in the skin and outer muscles and he would slowly bleed out internally, except for his lungs where he would bleed out in about a minute.

He was a botanist, so that he knew about hex without "knowing" hex is neither surprising nor egregious. The better question is why the hell didn't he have any music on his own laptop?

I really thought they explained he pointed the pathfinder antenna at one of the satellites, but I may have misheard/misunderstood that.

Simulating Mars gravity accurately would have meant putting not just Damon but all of the stuff he picked up, set down or dropped on a rig. That would have added considerably to the soundstage costs, which I'm sure were already considerable. Given that the movie was about Mars and not Gravity, I happily give them a pass on this one. They did well with the zero gee simulation on the Hermes, I think.

Sound is also a quibble. Almost everything was presented as being heard through the suit mics. The docking and EVA were bad, in that no one was tied down, and the guy crawling over the ship, while not unrealistically done, would have been better portrayed by using a SAFER pack.

I thought that the huge glass windows in the Hermes were the most unrealistic, unscientific aspect of the movie. Structurally not as sound, and a hazard for both radiation and micrometeoroids.

Regarding the punctured suit, during the incident in question on the shuttle EVA the astronaut was injured and his blood sealed the hole ( http://www.geoffreylandis.com/... ). The bigger question, I think, is how large a hole would be required to produce any usable thrust without being so large that there's no explosiveness to the decompression?

The slingshot and gravity assist were, clearly, not "genius" ideas, but more dramatic substitute narration. Unnecessary, but typical Hollywood, so shouldn't be a surprise. And they lifted a from a lot of other movies than Apollo 13 including 2001, various Star Treks, Aliens, and most directly, Lord of The Rings.

Depends how fast. If it was more or less instantanious you'd be dead in seconds from your lungs imploding and other massive internal organ damage and internal bleeding.

Only if you tried to hold your breath, apparently.

http://www.geoffreylandis.com/...

Humans hae survived vacuum exposure and lived to tell the tale.

As to it taking less fuel to get to mars then the moon... How? Just explain how that is possible.

Aerobraking. The vast majority of your spacecraft's fuel and cost is spent getting out of Earth's gravity well. If you've burnt enough fuel to get into a lunar transfer orbit, it takes just a little bit more to escape Earth entirely and go to Mars. But to *land* on the Moon, you need to spend more fuel to slow down and stop on the surface. To land on Mars, you just need a heat shield, because Mars has an atmosphere you can use to slow down.

http://en.wikipedia.org/wiki/D...

So that's reason #1 why Mars's atmosphere isn't a joke.

I'm quite certain you could "throw" things from the moon to the earth. So the return trip wouldn't even take fuel. You could literally just give it a push.

Unless you can throw things at 2.4 kilometers per second, no. The Moon's gravity is less than the Earth's, but it's still serious business. You need quite a bit of fuel to take off from the Moon. You need fuel to take off from Mars too, but Mars's atmosphere has carbon dioxide: bring a little hydrogen with you (or use the local water) and a source of energy (solar panels or a reactor) and you can synthesize methane and oxygen fuel while you're there. No need to carry fuel for the trip home!

http://www.geoffreylandis.com/...

Reason #2 why Mars's atmosphere isn't a joke.

[Mars's atmosphere] is not enough to appreciably reduce radiation to the surface.

Oh, but it is. Mars's atmosphere is thick enough to shield radiation about as well as several inches of concrete, reducing radiation exposure by a factor of 2-3. It's also further from the Sun than the Moon, which reduces solar radiation by a factor of 2. Neither of these effects are enough on their own: you're right that Mars habitats will have to be underground too. But going outside is noticeably safer.

http://www.lpi.usra.edu/lunar/...

Reason #3 why Mars's atmosphere isn't a joke.

Mars's atmosphere doesn't provide complete radiation shielding, but it does provide complete protection from meteorites up to about 1-2 meters in diameter.

https://janus.astro.umd.edu/as...

Reason #4 why Mars's atmosphere isn't a joke.

And finally, the Moon has craters and lava flows and that's all. Mars has those, plus volcanoes and canyons and ice caps and wind and clouds and storms and snow and glaciers and sand dunes and landslides and groundwater and river valleys and maybe an ancient ocean and maybe, once upon a time, life. Why? Because Mars has an atmosphere.

Reason #5 -- the most important one -- why Mars's atmosphere isn't a joke.

As to why not do it on earth? That question doesn't even make sense.

It was a rhetorical point, not a serious proposal. I'm saying that if you're going to spend your whole life hiding in a sterile burrow, does it really matter that you're on another planet?

For the record, none of these ideas are my own. I'm quoting chapter and verse from "The Case for Mars" by Robert Zubrin. Zubrin's got his problems -- he's a little too casual about the radiation dangers, for instance -- but IMO it's a good starting point for any serious discussion of colonizing the solar system.

http://www.amazon.com/Case-Mar...

A human would have approximately 5 to 10 seconds in which to respond to the tear in their suit, and if repressurized within 60 seconds, have a fairly good chance of survival.

From the source:

Has Anybody Ever Survived Vacuum Exposure in Real Life?

Human experience is discussed by Roth, in the NASA technical report Rapid (Explosive) Decompression Emergencies in Pressure-Suited Subjects. Its focus is on decompression, rather than vacuum exposure per se, but it still has a lot of good information, including the results of decompression events involving humans.

There are several cases of humans surviving exposure to vacuum worth noting. In 1966 a technician at NASA Houston was decompressed to vacuum in a space-suit test accident. This case is discussed by Roth in the reference above. He lost consciousness in 12-15 seconds. When pressure was restored after about 30 seconds of exposure, he regained consciousness, with no apparent injury sustained.

Source:
http://www.geoffreylandis.com/...

The use of a form-fitting pressure suit, like that used by a fighter pilot (or those being demoed by MIT for use on mars, which have form-fitting metal coils to supply mechanical compression) would buy the suit occupant even more time in the event of a tear in the suit by preventing ebullism, and resulting drop in blood pressure, and resulting loss of consciousness.

There are a number of potential mechanisms that could be implemented into a space suit of the MIT type, that would make abrasion type holes in the suit less lethal, such as the non-newtonian silicon shear thickening liquid that is used in ballistic vests. A thin layer of this inside the suit would harden under the pressure being exerted on it by the occupant of the suit against the reduced pressure outside, exerted through the tear. This would reduce the effects of the hard vacuum on the suit occupant, buying more time to apply an appropriate patch to the suit.

Well, the National Space Society already has a space roadmap:
http://www.nss.org/settlement/...

I will also unapologetically list my twenty-some-year old Footsteps to Mars, presented at Case for Mars V, Boulder CO, 26-29 May 1993.
http://www.geoffreylandis.com/...
http://www.wired.com/2014/03/f...

You are right, the effects of a vacuum are vastly overblown in movies and books. The first thing i looked up when i saw the comment about punctures in the summary was this http://www.geoffreylandis.com/vacuum.html which includes a bit describing when one of our astronauts had a 1/16th inch hole punched through his suits glove. The same page goes into some details on the effects of vacuum on people.
part of people's problem with vacuum, is they seem to mentally correlate it with pressure like on a submarine. In a submarine, at depth, you have thousands of pounds of pressure pressing inward on the hull, and a puncture is catastrophic, a needle of water that can cut like a razor. people mentaly invert this situation when thinking of vacuum. They assume the same is true, only in reverse.
The truth is, the difference in pressure between the inside of a space craft, and the outside vacuum is more or less 1 atmosphere. That is a *tiny* amount of force. which is why they could build the lunar lander walls 'the thickness of a couple sheets of tin foil'.
the reason our current suits are so bulky is not mainly for puncture prevention (although there is some of that) its largely for insulation/radiation barrier. and to cover the large amount of weird gear that the astronauts wear to stay at a safe temperature. a suit of underwear with tubing knitted in that carries liquid that is either warmed or cooled, depending on what the need is, among other things.

... After RTFA, I was a little concerned;

- The presumption is that the stuff they actually can't see doesn't 'seem' like anything else, except it does 'seem' like water. So they think it's water. I'm a little concerned they went out on a limb here, but nothing that couldn't be settled by sending up a rover and tasting it. Right?

- All the ideas that colonizing the Moon if for no other reason than to launch from there seem to think the Moon has, among other things, minimal problems with waste, pollution, and climate change. Nothing could be further from the truth. We've sent precious little there, and already thre are concerns about potential pollution and abuse .

By all means, let's get up there and mine out all the water, uranium, and silica before someone else does! Sure!

ps- I think there have been complaints about how we have treated the Moon and other objects.

FTFA: the White House is more intrigued by missions to asteroids and Phobos and Deimos as a precursor to a human landing on the Red Planet in the distant future.

This is great news. A mission to Phobos would make a lot of sense. It has a lower delta V than a moon or Mars landing. It is estimated to require half the propellant and hardware weight compared to a mission to the surface, half the mission cost, and significantly lower risk due to the fact that no surface manned lander is required. More importantly, it has less than half the engineering and development cost (and time). The other big plus is that there is no rotation so the mission would be protected from radiation by Phobos on one side and Mars on the other. The only question is whether the Russians will beat the US and get a manned mission there first. They have been looking at going to Phobos for a while now. They have an unmanned mission going there and returning with samples scheduled for 2011.

I apologize for unclear writing. I didn't mean to imply that NASA was still trying to handle all launch needs. I was referring to the dark days before the Commercial Space Launch Act:

From the beginning of the Shuttle program until the Challenger disaster in 1986, it was the policy of the United States that NASA be the public-sector provider of U.S. launch capacity to the world market.[4] Initially NASA subsidized satellite launches with the intention of eventually pricing Shuttle service for the commercial market at long-run marginal cost.

http://en.wikipedia.org/wiki/Private_spaceflight#American_deregulation

Clearly private launch is not killed now, given that SpaceX is taking over resupply of the ISS! But it would have been rather difficult to get SpaceX funded in 1983 or so, would it not?

My first-ever conversation with Geoffrey Landis and it's about my vague, unclear writing? Pardon me, I need to go weep in a corner.

steveha

"Spacesuit puncture is not nearly as dangerous as you think ", sayeth you. The link, however, does not sustain this statement:

"It is very unlikely that a human suddenly exposed to a vacuum would have more than 5 to 10 seconds to help himself. If immediate help is at hand, although one's appearance and condition will be grave, it is reasonable to assume that recompression to a tolerable pressure (200 mm Hg, 3.8 psia) within 60 to 90 seconds could result in survival, and possibly in rather rapid recovery."

It is rare even on Earth, with our concentration of people, that an accident victim can be helped within 60 to 90 seconds. Look at auto racing - there are teams ready to go on a moment's notice, and they do go even before the debris stops flying - and nevertheless they need about half a minute to just reach the site of an accident. Then you need to access the victim and do whatever needs to be done.

So imagine that you are a worker on the Moon. A small avalanche immobilizes you and tears your spacesuit in a few places. If you haven't radioed for help within seconds you are as good as dead. If you have a buddy always with you, chances are that the buddy is sharing your fate. If he was keeping his distance then he is welcome to start lifting stones - he has at most 90 seconds to free you, patch your suit up and recompress from a spare oxygen bottle. Secondary damage, like severe bleeding, can be controlled on Earth but is impossible to stop on the Moon. If the guy bleeds to death, or drowns in his vomit, or has a heart attack, blame vacuum - these are often survivable situations when a rescuer has access to the body of the victim.

Given that even on Earth the buddy system is used only rarely, on most dangerous missions (diving, fire, nuclear) - what is the likelihood that a Moon team will include people who do nothing but just tag along and watch your back? We routinely have police officers doing potentially deadly traffic stops alone; we have miners who work in their own section of the mine; we have steel mill workers who control rivers of fire alone; we have air traffic controllers who make decisions about life or death without anyone available to look over their shoulder and, once in a year, shout "belay that order." I don't say it's a good thing, but if we operate like that on Earth, where a buddy is relatively easy to get, what chances does the Moon have?

On the Moon the vacuum will be a major killer because an accident that on Earth leaves you with a minor wound will puncture your spacesuit and you'll be dead as a mummy before anyone can pull you to safety.

Spacesuit puncture is not nearly as dangerous as you think

Who cares if it is hard? It is that difficulty that should be making us want to do it!

Indeed. But we should do it in achievable footsteps.

Not one quick flags and footprints mission. Step by step, building capability all the way.

I can see an argument of humans vs space probes, but the idea of putting the humans in orbit to release the space probes seems to be the worst of both worlds.

If we are going to send humans out there, they should be landing on something, otherwise send probes.

It turns out that the last 200 kilometers, getting from orbit to the surface and back, is vastly, completely, incredibly the hardest part. It is much, much simpler to get humans into orbit than to land them on the surface of Mars. Among other things, to land on the surface, you need design, build, test, quality, and fly two additional vehicles, a lander vehicle and a launch vehicle, both of which are flying in regimes that are hard to engineer for. Not to mention a long-duration habitat for the Mars surface, and spacesuits that will survive for hundreds of EVAs on the Mars surface-- not easy.

Orbiting Mars is vastly simpler than landing on it.

Of course, I've talked and written on that subject many times before-- Teleoperation from Mars Orbit: A proposal for human exploration, Footsteps to Mars, etc.

(I agree, however, that L-1 is silly-- nothing there to explore.)

These are pretty much general principles in life that apply everywhere....

Sure. Just like, "Everything I really needed to know about life I learned from playing Tetris"

Jeez - read the abstract. Its a calculation based on a theoretical model using some very speculative physics for which there is NO EVIDENCE WHATSOEVER. Really. Ignore it.
The main thing to keep in mind is, cosmic rays have energies vastly higher than the LHC. If the LHC could produce black holes, then there would be black holes floating around everywhere.

at 63,000 is the Armstrong Line or Armstrong Limit. The oxygen in your blood "boils" out, in that it turns into vapor. Now, let's see, air we breathe passes in and out of our lungs...see a problem here? What a rapid decompression results in is damage to the lungs (and heart and CNS). No delicate way to put it. The lungs "explode". Now, let's not think Hollywood special effects. Each little--okay, many--little airsacs in the lungs rupture from differential pressure. This is called ebullism. For you reference folk, check out Wikipedia Armstrong Limit, although the entry there isn't entirely correct, or more accurately, complete. More importantly check out its 2nd reference. Here is the reference for simplicity: http://www.geoffreylandis.com/ebullism.html It's not crap, folk. It's physics.