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Six Minutes of Terror - Landing Humans on Mars
Posted by
Zonk
on Thu Jul 19, 2007 05:22 PM
from the our-red-buddy dept.
from the our-red-buddy dept.
OriginalArlen writes "Universe Today has a fascinating article discussing the difficulty of executing EDL (entry, descent, landing) on Mars for vehicles bigger than MER, Viking and Pathfinder, and the challenges for manned craft in particular. Airbags can't be used for obvious reasons, but the atmosphere is too thin to be used for parachutes or aerobraking by large heavy vehicles. The stronger gravity (compared to the moon) makes an Apollo-style powered descent impossible. The best current idea is a huge inflatable torus called a hypercone: 'Imagine a huge donut with a skin across its surface that girdles the vehicle and inflates very quickly with gas rockets (like air bags) to create a conical shape. This would inflate about 10 kilometers above the ground while the vehicle is traveling at Mach 4 or 5, after peak heating. The Hypercone would act as an aerodynamic anchor to slow the vehicle to Mach 1.'"
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Why land? (Score:5, Funny)
Oh, wait...
Re:Why land? (Score:4, Funny)
Were you talking into your mouse when you said that?
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Re:Why drop? (Score:5, Funny)
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Impact (Score:5, Funny)
Re:Impact (Score:5, Funny)
Don't worry! We'll just tell Quaid to start the reactor [wikipedia.org]. Oh, wait...
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Re:Impact (Score:5, Funny)
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Re:Impact (Score:4, Interesting)
This is where design validation comes in. For those not familiar with this term in the context of system engineering (and, in particular, system engineering of complex aerospace/defense systems), design validation generally refers to the activity whose purpose is to show that a design actually meets the customer's needs (i.e., that it is a 'valid' design). The effort takes design requirements into consideration, of course, but should also make use of system modelling based on the design, among other inputs.
Assuming the statement of work includes support for design validation, and the team doing the validation is competent, a lot of the risk of incomplete requirements can be mitigated, at least in theory. However, the engineering of complex, never-been-done-before systems always has associated 'escape' risks. A lot will depend on how the development effort is phased, and whether or not sufficient system engineering is performed up front, with sufficient lead time to modify/add to the design without severely negatively affecting the overall development in terms of cost or schedule.
In the end, of course, dealing with a competent and ethical development group is key. In my opinion, the contracts folks shouldn't "get in the way" of doing the right thing if problems surface. But in today's world, with today's financial sensitivities--and today's ethics--there are risks.
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Re:Impact (Score:5, Insightful)
LOL. I was once in Aruba and I rented a one of those Ski-doo things. I revved the fucker up to 55 and went off. Then I made a turn. Well, G-Forces took over and I went flying across the ocean. Now, you'd think water was soft (I know YOU don't because of your post, but others...), but when I hit it, it felt HARD. So, I went again, and did the same thing...well, look at my user name...duh! (I live up to it, man!)Oh, the water was still fucking hard at 50+ MPH!
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Re: (Score:3, Informative)
Re:Impact (Score:4, Funny)
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Parachute? (Score:5, Insightful)
Re:Parachute? (Score:5, Funny)
--Vorticity Ltd.
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Re:Parachute? (Score:5, Funny)
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Re:Parachute? (Score:4, Funny)
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Re:Parachute? (Score:5, Funny)
Hitting the ground mach 3 slower.
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Re: (Score:3, Insightful)
Space ladder? (Score:4, Funny)
Re:Space ladder? (Score:4, Interesting)
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Hypercone looks like... (Score:5, Funny)
I wonder when that idea...uh...arose?
Space Elevator? (Score:5, Interesting)
Re: (Score:3, Interesting)
Re: (Score:3, Informative)
Re:Space Elevator? (Score:4, Interesting)
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Re:Space Elevator? (Score:5, Funny)
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Mach 3 Chute (Score:5, Informative)
Also, the problem with a retro rocket the whole way isnt just that its heavier gravity (just means more fuel,) but also the process of igniting a rocket with an incident airflow of mach 3 or higher is not a trivial problem.
Overall, Mars is the hardest place to land in the inner solar system. the Moon and Mercury are small and have no atmosphere, so Apollo is an obvious and easy choice. Venus has an atmosphere so thick you can drop any funny shaped item in and it will drop to the surface at low speeds, assuming the static heat doesnt destroy it. Earth, obviously, you can do well enough if you're careful with the shape and throw up some parachutes at the end. Mars though has such a thin atmosphere it makes everthing hard.
This concept sure looks interesting though.
Re:Mach 3 Chute (Score:4, Insightful)
They already have designs that work, simply triple them up. They are also going to haveto do a powered decent no matter what, you are not going to get a plane to get any bite in that atmosphere at all (although a delta wing would be able to do breaking maneuvers lust like the shuttle does so it might not be a bad idea.)
Honestly they will have to send a robotic test mission like they did with apollo unless they are willing to accept a "oops" moment as we hear the news that 7 astronauts plummeted to their death because someone divided by zero.
The support ship will have to be huge, and the dry run with the support ship is not only a great idea, but will also tell us if the astronauts will get there with only one left and all the rest for some reason went for a walk and will be "back real soon now"
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Re: (Score:3, Interesting)
The real challenge is that no matter what you do, you are moving *fast* at the beginning of the entry to the Martian atmosphere.
1) Very Large Heat Shields. The primary challenge to this is that it is next to impossible to launch them from earth. So don't launch them from earth-- assemble in earth orbit instead. This would require switching to more established systems after reaching mach 1.
2) Ver
Oh Yeah? Try Landing on Jupiter! (Score:5, Interesting)
I'm a little bothered that the article dismisses as useless components that in actuality will probably be used for landing on Mars and are unrelated to the problem addressed in the article, and it tends to treat each idea as a complete solution, rather than pieces of a multistate solution.
The problem is not touching down on the surface. It's that first bit of decelleration during which you cover most of the distance to the ground. You've got to bleed off a lot of speed really fast, and Mars atmosphere isn't very conducive to accomplishing that. The article does cover this part well.
Previous landers, especially the Mars Exploration Rovers, have used multiple stages. The first is the heat shield. Because of their small size, the MER's have a high surface area/mass ratio. The heat shield slowed them down to mach 2 and a supersonic parachute deploys. Then retrorockets fired, slowing it to a complete stop a little ways above the ground, and lastly, the cable cut, dropping it relatively gingerly onto the airbags.
So just for the little MER's, there were actually 4 stages involved: heat shield, parachute, retro-rockets, and airbags. Although the article on focus on the airbags in its discussion of the MER, those were really only to allow a margin of error for the retrorockets (although a needed one), and were unrelated to the supersonic transition part.
The hypercone is basically a specially-shaped parachute, but it still won't slow a lander sufficiently to survive hitting the ground. I'm expecting the final solution if we ever commit to it will include heat shield, hypersonic chute, possible a middle stage chute, main chute, retrorockets, and airbags.
Also, you mention lighting a rocket in a supersonic airstream is hard (I'm not sure about that...the combustion chamber is static), and the article claims it would be better if Mars had no atmosphere. Regardless, if you're committing to rockets for anything more than what a modestly sized parachute leaves you travelling, then it doesn't much matter if you use the rockets down near the ground, or as part of a longer de-orbit burn. Either way you're getting rid of KE.
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Re:Mach 3 Chute (Score:5, Funny)
I think the sun presents a greater issue.
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One lander per person? (Score:4, Interesting)
Mmmmm... RAIA (Score:3, Funny)
The real question is (Score:5, Insightful)
Probes are an extension of humanity's collective intelligence, and they bring back to humanity at least as much data as a real, flesh and bone human. So why send humans at all? Of course, if we're talking about colonizing Mars for good, there's some terraforming to do, but heavy machinery isn't necessarily required for that either, and it's not going to start within our lifetime anyway, and the planet won't be ready for us in 200 years minimum anyway.
I say forget about hauling big stuff over to Mars. The only folks who care are prez Bush, for demagogic purposes, and people who think watching a Neil Armstrong type character utter some silly piece of wisdom when setting foot on a planet is the pinnacle of human space exploration. What we need is more research into nanotechnology, so probes get smaller and lighter, and educating people.
Re:The real question is (Score:5, Interesting)
Do we really need to land heavy stuff on Mars? "Something heavy" here means some spacecraft with human creature comfort (you know, a hull, life support systems, etc... in order to keep wetware inside alive). However, there is no need for manned flight to other planets anymore: probes do a much better job more easily, at a fraction of the cost, and a probe's survivability is much less of an issue.
Probes don't do a better job of colonizing other planets. Terraforming Mars is only a step in its colonization. The first and most important step is having people live on Mars. Second, there are all sorts of unpleasant things that can happen to people on Earth. In addition to the small chances of extinction, I think there's a good chance that we reset civilization in the next century or two. Aggressive space colonization can get us a foothold in space before nuclear war, a biological weapon, or other human-made disaster can set back Earth-side civilization to the early industrial age or earlier. Alternately, we could face centuries or millenia of stagnation in a "water empire" [wikipedia.org] style government. In other words, colonizing space, particular the Moon, Mars, and other select bodies is a great way to diversify the habitat of human life.
We could wait for the next big technology advance like nanotech, or we could get started with the capabilities we currently have rather than count on the uncertain future to do our work for us.
Another point is that we can expand our economy into space. Sure you can expand it profitably into deep ocean, Antartica, etc. No reason not too unless you're an environmental type in which case you should like the absence of an environment to harm in space. But space has the benefit that there's a lot more of it with a lot of energy and mass available, dwarfing anything available on Earth. Economic expansion past a certain point will require a presence in space.
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Robots should build a landing strip first (Score:5, Interesting)
We should send a massive fleet of robots down and they can build a runway of some sort. Once they've finished that, they can also build a little village complete with a bar. That way when people go to mars, they have a place to land, and then they can get a drink and maybe some munchies.
Why not a parachute (Score:3, Insightful)
So. . a parachute then?
On a serious note, why not use a parachute? They've been used before on many missions to mars to slow the vehicle down before the retrorockets fired. I mean I understand the hypercone would work too, but I dont understand why a larger and/or more parachutes wouldn't. Then again I'm no fluidynamicist (is that a word because it sounds really really cool).
One word. (Score:3, Interesting)
Unit conversion (Score:5, Interesting)
The true terror begins (Score:4, Funny)
Stop wasting time on Mars (Score:3, Interesting)
Six minutes of terror (Score:5, Funny)
Re:Six minutes of terror (Score:4, Funny)
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Re:Make up your mind (Score:5, Informative)
The landing setup they're proposing is actually more like an air-braking system. It inflates around the lander while it's still at a high enough altitude, giving the lander a considerably larger volume. This would hopefully slow the lander as it continues its descent.
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Re:Make up your mind (Score:5, Informative)
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Re: (Score:3, Funny)
Re:Same way they land on Earth (Score:5, Interesting)
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Re:Same way they land on Earth (Score:5, Interesting)
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Re:Same way they land on Earth (Score:5, Informative)
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Re:Message for Humanity (Score:4, Funny)
All your base are belong to us
You are on the way to destruction
What you say!
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Re:Why mess with Mars? (Score:5, Insightful)
wrong. More in a moment.
"You would need to send enormous amounts of gear, several hundred tons of water
and food and air enough for the journey, the time spent on the planet and
the trip back. "
and
"You would need a "mother ship" and at least two 'landers' with return
capability. In addition, a habitat for the humans. If you think you are a
treehugger, imagine the colossal amounts of resources needed to get there
and the environmental impact on Earth, just to start this type of endeavor."
Because it's hard is why it should be done.
"Think people. That grey matter is supposed to be used."
You first. I mean really.
Now back to the first part...Why?
1) The resulting spin off products will create new spin off companies.(The taxes returned from the companies that sold products created from the Apollo missions had gotten 13 time the return in taxes then the Apollo cost.)
2) New technologies and RnD help drive science.
3) This would almost certianly be a global project. Big Global Projects can help bring people together.
4) The environmental research and technology would help us develop a better understanding of enviromental controls on earth.
5) So we can stick out our just chest and say "Been there, where to next?" Not to consider the emotional impact on people is foolish.
6) More experience with space flight is another step towards off world mining and colonies.
Yes, there should be robotic exploration as well.
Personal, I would send drop ships to drop supplies before humans left for mars. Complete satellite arrays, rover to scout out select landing zones. Maybe even send the returning vessel ahead. Pack it with what they will need to return, and nudge it to mars. No rush, you can send it a couple of years ahead of time. You could also send some different landing tests.
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Re: (Score:3, Funny)
What amusement parks do you go to?