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This article (http://www.universetoday.com/2008/03/04/a-one-way-one-person-mission-to-mars/) reminded me I've had this recurring question I keep forgetting to look up answers for.

We can go to Mars.
We can orbit Mars.
We can land on Mars.

But how the hell do we get back off of Mars? This isn't marshmellow-weight Moon here. We sending in a zerg of drones (led by Falconeer (http://forums.f13.net/index.php?topic=12524.0), yar!) to build us a launch pad? Dropping a space elevator? Something else?

Or is that the reason we haven't sent people yet?

The most sensible plan I've heard involves sending large quantities of supplies including fuel for the ride home to a supply dump on Mars before the astronauts even arrive.

But that still doesn't get them from Martian soil into Martian space. Unless those supplies include afforementioned launch pad and vehicle? If we're truly back at rocket-based launches, you gotta build quite a bit to duplicate that on Martian soil. Not as much atmosphere in the way, but there's still that graviity, no?

A return trip from mars is somewhat similar to the Moon landings in that you have a vehicle which orbits the celesital object in question with enough fuel for a return trip.

The kicker for a Mars trip is that you cannot carry enough for a 2 way trip up in one launch, so you send an un-manned vehicle with the return trip fuel to orbit Mars, which you then rendesvous with after leaving the surface in your lander return module, and you fuel up and come home.

The tricky parts come in communication as much as anything as there is quite a noticable delay in response from communications sent/recieved so in the case of an emergency, the crew would need to be able to be nearly 100% self-sufficient. Think more along the lines of the old Sea explorers when they went out of sight of land for the first time.

So we can land enough on Mars that can launch off the surface back into space? I thought the gravity was similar? Is it that the launching vehicle doesn't have as much friction to deal with on the way up? If not, I'd think if we could do it there, we'd already be doing it here.

Part of what jogged this memory was that godawful Val Kilmer flick. Hanging onto something the size of the Mars Rover that has enough oomph to get off the ground nevermind into low orbit? Really?

Part of the Mars rover missions have been to analyze the soil on the Martian surface to see if there were any minerals present that can be processed into fuel for a return trip, thus greatly decreasing the amount of fuel.

And with almost no drag, and a considerably lower gravitational acceleration, we would not need really all that much fuel to return the crew and what little material they would be bringing with them back into orbit.

(sorry for the double post if there is one..I got sidetracked by a phonecall mid post)

I assume their landing vehicle is going to be something along the lines of the space shuttle so that once it's refueled it's able to get them back to their ship in orbit. 

Mars gravity is 3.96 m/s2 and the escape velocity is 5.027 km/s, if you compare that to Earth's 9.78 m/s2 gravity and 11.186 km/s you can see the difference is pretty substantial even not taking into account the atmospheric drag.

Add into that the difference in size of the launch vehicle and it becomes all that much easier.

Ah, ok, that's the part I was wondering about. With a lot less drag I assume they could go with some sort of runway-type spaceplane launch?

Sorry for spamming the thread. I've always been curious (but apparently never enough to, like, look it up...)

Most likely it would be a more traditional unpright rocket type launch. They might launch at a lower angle, but usually it is easier to launch "straight up" and then tweak your vehicle after liftoff to put it into an ideal ballistic trajectory. It is what the Shuttle and other orbital launches do from earth now.

Since their is little to no aerodynamic forces on Mars, any winged vehicle would simply be for show.

So they'd have to build the rocket and launchpad when they get there?

Not necessarily, more than likely the landing vehicle would have the return-to-orbit launch stage and return vehicle integrated into it, and they would simply pile back into it to return to orbit.

Much like the Lunar landers, whose landing bases acted as a launching pad for the crew capsule and were left behind.

I question the need to send humans to mars in my lifetime.  We should keep sending more robots and more equipment for the robots to use.

And what, actually prepare for evil robot overloads (http://en.wikipedia.org/wiki/The_Caves_of_Steel)?  :grin:

Ah ok.

Edit: Fixed code thingy

We should go, only because it always spawns a whole raft of auxiliary technology that gets invented on the fly that ends up advancing science in the long run.

Yeah, we really need to concentrate on sending people to the moon, and living on it.  The logistics of sending somebody to mars is god awfully complex and expensive (not to mention time consuming due to the long trip).  We can build up our technology for space travel/habitation by practicing on the much closer and much easier to land/take off from Moon.  Once we have that down, then we can start building launching pads from the moon/orbit which allow us to launch ships designed way better for long distance space travel (as opposed to trying to get it off the earth, which limits the space crafts ability greatly).

But keep sending probes and stuff to mars, yeah.  Lets just be practical here about developing human habitation in space, heh.

The thing is though that getting a human on Mars excites the fucking LCD masses, or at least hopefully they aren't so far gone that it will excite them.  We need that so NASA and science in general gets a bit less scorn and a bit more love.

tl;dr

fucking christians + fucking GOP + fucking anti-smart movement in america = NASA needs to put on big show for stoopid people, not do practical, scientific shit.

Oh yeah this isn't Politics, ignore that bit  :uhrr:

I propose a cheap suicide flight with no return.  If you want the privilege of being the first man to set foot on another planet you should be prepared to die for it!

I read a while back that one major hurdle yet to be overcome in a manned mission to Mars was the problem that the solar radiation would kill the whole crew long before they reached their destination; and that the international space station has to have a panic room where the crew retreats during Solar Storms. However I can't find mention of this now, so I may be mistaken.

No, you're right. Radiation is a huge issue. As is mission length in zero G. And medical treatments, you will need a genius of an ER doc who can handle everything up to complex surgery...in zero G.

It's a thorny prospect, goddamned cowboy president moron.

However, I'm overall in favor of the attempt, because a lot of good research should come of it. I do mourn the loss of the scientific missions scrapped to pay for it, I wish cowboy had ponied the cash so NASA didn't have to cut other stuff.

That really sums up a lot of the issues I have with the current "plan".

Going back to the moon first, setting up a staging base + more stuff there, and then going to Mars would be a better idea. Plus, the less expensive and less technically challenging robotic missions should not have been cut just for a single "hey well we went to mars first" mission.

The space station is protected by Van Allen belts, so only during the worst flares do they even notice anything -- and I have no idea offhand if they have any sort of even semi-shielded room. However, I do know that all electronics on both shuttle and station are heavily shielded (there's a lot more EM floating around out there) -- one reason that NASA is very slow to upgrade computers and laptops. Their computers are hardened against excessive electromagnetic radiation.

(Funny story -- NASA held off upgrading from 386-based laptops to something faster for years. When they finally upgraded a pair of test laptops, and had the astronauts use them, the damn things would stop working after about an hour. Why? In space, heat doesn't rise -- so it formed a bubble around the chip, something that was not considered by the folks contracted to harden and make "space-worthy" the laptop. You'd be amazed at how much engineering and technology relies on gravity...in ways that are often hard to notice).

But yes, even during quiet periods of solar activity, the odds of astronauts encountering at least one flare are unacceptable unless they take a very high velocity transit. (For the Apollo astronauts, well, they were only out there for a short while -- the risk was considered acceptable. One flare, and you'd have had a bunch of dead Apollo astronauts). There are shielding possiiblities, but those require lots of mass. So it's either lift hundreds of tons of extra mass for shielding, or lift hundreds of tons to make a much faster trip. It's a serious problem and expense either way. There's also the issue of muscle and skeletal degeneration on a slow approach, which is one key reason for ISS -- long terms in space are kinda necessary for that sort of research.

Doctor and even surgery aren't really that much of an issue -- astronaut first aid training is rather thorough, and any Mars mission would send a trained surgeon. They're worried more about accidents than illness, as astronauts are probably the most thoroughly vetted folks, health-wise, around. The german spacewalker who got "sick" didn't have an illness -- he was spacesick, and it took him longer to adjust to zero-g than was hoped, even with drugs.  The first day of any flight the astronaunts are not expected to do too much, not compared to later -- adjusting to zero-g is a pain in the ass, even for people who have done it often.  (The space shuttle's first-aid kit is surpisingly full -- including, as I learned several flights back, medical staples. There's a suture kit there too, so it's not "we'll just staple this godawful cut back together and sew it up back on earth". Trust me, someone on that flight is well-trained enough to use those tools -- even without the aid of a flight surgeon).

Heh the more you know :)

I know airline pilots have a 10,000 times higher (or thereabouts) incidence of eye cancer due to exposure to solar radiation, and they don't even leave the atmosphere. It's definately a big hurdle to overcome.

I think the other simple problem that hasn't been considered is the matter of food. Even the ISS needs to be resupplied every what.... 40days? The hop to Mars is going to be on the near side of 3 months if I recall right, and that's only one-way. There's no way to raise any form of animal on board, and even growing plants is a big deal; again radiation would kill them faster than it kills us. Maybe some form of highly nutritious algae... Although many modern subs are rated for up to six months underwater and they have crews of hundreds, how do they make do for food, or is that just a theoretical limit imposed by oxygen. water, power and waste recycling systems?

And how do you stop the crew going postal after 3 months of zero G and nothing but algae to eat?

Plus... What happens when they get back from Mars and they discover the Earth has been taken over by damned dirty Apes??!! WHAT THEN!!!

The Discovery Channel did a nice overview of the issues with a (wo)manned mission to Mars late last year in a series called Mars Rising.  Was even in HD.  There's a shitload of stuff you've never even thought about.  The radiation was a big one.  They're considering encasing the entire ship in a layer of (absurdly heavy) water for protection.  Even then, they'd need an extra-shielded module to hide in during big flare-ups.  Note that these flareups can last for days or weeks.  So you have to be in the little bunker module that whole time.  Then there's the fact that the Mars surface is constantly covered with electrical dust storms that would short out any gear and block out the sun (and can last for weeks).  Plus there's the extra weight of all the food, water, and convenience gear.  And the probability of 5 or 6 men or women living within 30 feet of each other for almost two years without going batshit fucking insane.  I was slightly for the plan before I watched the series.  Now I think it's fucking stupid grandstanding and an obscene waste of money.


I think you'd get most of the good research with unmanned trips, and they'd cost about 2% of the manned version.

I always figured game playing could solve that. They might come home addicted to WOW, but at least they'd survive cabin fever.

Something against that is, I think the personality type who's apt to tackle a space mission isn't the type who would play video games for hours at a stretch.

Simple solution to the problems with the Mars trip - use an Orion/Daedalus-type spaceship. Fast, huge ship with lots of shielding and space for supplies, etc etc.
Just...build it in orbit and be careful with the fuel.  :drill:

I'm still hoping Bussard's fusion reactor ends up working out. $25/kg to earth orbit, then 40 days to mars sounds nice.

The latency from Mars is terrible.  They'd be pwned.

Unfortunately, Mountain Dew and Cheetos aren't suited for consumption in space.

We already have quite a bit of research on that -- Arctic stations, submarines, and even ISS. It takes a great deal of screening, training, and careful assesment of personality types and intrapersonal relationships that will vastly complicate crew choice, but the five or six people that close together thing isn't insurmountable. It's quite addressable.

Mars dust storms and the like are pretty predictable, but it does make basing underground pretty important. One reason for a sort of Mars Direct approach -- drop off the heavy (and shielded) equipment for years before hand, including automated digging equipment. Leave only the detail work and the stuff that can't be done by time-delay remote to the crew proper.

I suspect a Mars trip will become far more likely if a space elevator becomes a reality. (We're closer to that than you can imagine. Last I checked, there remained two major engineering hurdles -- carbon nanotubes cannot currently be grown in the required length (about a foot -- they're up to three or four inches now, from millimeters five years ago) and during elevator construction there's a three or four month period where the ribbon is too slender to handle a micrometeorite strike, but wide enough to make one fairly likely. (After that point, the damage is merely repaired by the next crawler heading up).

A space elevator drops earth-to-orbit prices by an order of magnitude, and even offers a really nice velocity boost to anyone wanting to head to Mars.

As I recall radiation again is another problem that needs to be overcome with space elevators. Unlike rockets and the shuttles which travel through the Van Allen belts in a matter of seconds, the elevators would move much slower, and so would be unsuited for moving delicate equipment and organic material into space. They'd certainly help with lifting raw materials for and orbital ship assembly though.

And the weight doesn't include any structural "glue" to keep the nanotubes together. And building the thing would require a large percentage of our GDP. And two decades.

The list does go on, but man oh man the frontiers it would open up if it was able to be built.. All things considered, I'd go with a launch loop (http://en.wikipedia.org/wiki/Launch_loop) instead. Which we could build right now if we wanted to.

Coincidentally, I listened to The Fountains of Paradise (http://en.wikipedia.org/wiki/The_Fountains_of_Paradise) this week.

If I had to pick a "Apollo project" of this decade, a launch loop would be it. Hell, we'll need something like this to get us out of the depression we're headed for. It could be this generation's hoover dam.

One of the plans for the return trip that I have seen is they send an initial unmaned flight that will be the extraction vehicel. This will land near the planned base camp and once there will have systems to convert CO2 into liquid oxygen and refill its tanks so before you even send the people the return ship is there/ fully fueled and checked out to make sure they have a way home.

Mars gravity is a good bit lighter than earths so the force required to get back off of it is no where near as much. Its not as easy as the moon but its a lot more doable than liftoff from the earth.

Oh, that reminds me of one of the other risks detailed in Mars Rising.  If the final, manned lander lands more than like 20 k from the supply drops, or if the supply drops aren't where they're supposed to be, or the drops are dispersed enough that they have to travel a lot to collect them, or if there's some natural impediment between them and the dumps, or if the rover that's supposed to get them to the dumps breaks down in some way, they all die.

Re: Space elevators.

K9: Actually, the bulk of the transit is within the Van Allen belts, making radiation really not a problem. I believe the geosynchornous orbit point is outside the belts, but I'd have to look that up. However, with crawler lifting capacity being several tons, shielding for organics isn't that much of a problem. I suspect the real cost for "people" movement would be automated safety mechanisms in case of ribbon collapse or crawler failure. Then again, since we're looking at a three-day journey from bottom-to-top, it's likely only to be used for heavy cargo.

Lifting people alone via rocket is probably more likely, just from that standpoint. One reason earth-to-orbit shuttle costs are so high is that the Shuttle works as both a heavy-lifter (60 tons) and is man-rated. Man-rating is expensive. Man-rating a heavy cargo ship is an order of magnitude more expensive. NASA is being damn smart with it's next-gen design (it looks like actual engineers told Congressman to go suck it) -- eliminating debris problems, seperating manned from heavy-lift, and reusing existing and proven technology all over the place. Much lower developmental costs, lower launch costs, faster and tighter turnaround, FAR more flexibility, and considerable gains in safety.

Bhodi: Actually, the "glue" isn't necessary. The nanotubes are embedded in the carbon ribbon -- it's really not all that complex, and the ribbon weighs surprisingly little. (Even all 26,000 miles of it). The cost is....surprisingly cheap. The Space Elevator folks are estimating about NASA's yearly budget for construction (10 billion) and even assuming that balloons by an order of magnitude -- you're talking the cost of a year in Iraq. It's cheap.

People are very serious about this -- the movers behind the project spent four or five years basically giving demonstrations and lectures at universities (and getting the shit grilled out of them by highly skeptical engineers), and they've actually got a solid proposal that's been vetted by a lot of people who didn't believe it was possible. Like I said, they have major engineering hurdles to pass -- but they've managed to convince a lot of people, and secure significant funding, for further research. Almost all from people who arrived highly hostile to the idea that it was possible.

One of my coworker's company (it's a mess of various contractors here) is doing some of the material research on the nanotubes and ribbon construction, and he happened to attend a presentation on it. (Part of an annual "What we're doing" sort of thing for higher-up company folks). It's much further along than I'd ever imagined, and the Space Elevator folks are aiming to do it with mostly private money.

And they made one good point -- the FIRST elevator costs the most. (You have to fire a tiny ribbon into space, and then slowly build onto it over a significant period of time, using heavier and heavier crawlers). The ribbons after that are, basically, free. You transport the material up the first ribbon, and just lower the next one down from geosynchronous orbit as a complete entity. Five years after the first one goes up, there'll be several more up and running all along the equator. And they're hoping to start construction on the first within the decade.

But why not the loop? I mean the elevator is nice and all, but we could build the loop now. Plus, it has a lot more benefits and none of the downsides. It's a hell of a lot better for actual tourism, it's faster, and can handle more tonnage. It's also cheaper.

RE: actual construction, within the decade, as soon as we can get the material out of the lab and into the real world, AND the ability to mass produce it. There's no ETA on that, as far as I know.

Uh, what are you guys talking about?  From what I can see, The current plan (http://en.wikipedia.org/wiki/Vision_for_Space_Exploration) that was initiated by Bush calls for exactly that.  Getting back to the moon first, setting up shop there, then jumping on to mars eventually, while continuing to send robots in the meantime.
So that is more or less what NASA see's as well.  I see alot more useful research coming out of trying to set up permanent habitation on the moon and perfecting better earth to moon transportation than building up for a mission to mars.

This thread, while easily the most interesting thread I've read anywhere in a long time, makes my brain hurt.

But in a good way.

I'd have to look at the requirements of a loop, but you're pegging actual construction of a loop starting in a decade -- it's about even with the elevator, and I think the elevator is safer. (It's necessarily isolated from everying, out in the middle of the ocean).

I'm not sure a loop could be built today (http://www.launchloop.com/todo.html)

And technology aside there will be significant issues stringing a line for a few thousand kilometers along the ocean and then raising it into the sky with a sufficiently negligible chance of hitting a ship and/or plane.

The plane issues remain for an elevator, but at least that's all in one place.  It'd be harder to cut off 30,000 square kilometers of airspace permanently.

When you say the bulk of the transit is within the Van Allen belts, isn't that bad? I was pretty sure the belts were the radiation zones and we survive in the gaps between them, but then I'm no astrophysicist. Or do you mean the bulk of the transit is outside the belts? Either way, I had no idea that the transit was as slow as 3 days.

Space elevators are possibly one of the most remarkable things ever, I hope one is built in my lifetime.

By "inside" I meant "between the outer belt and the earth" not like actually inside the belt -- it was phrased badly. Being IN the Van Allen belts sort of suck, and I think the endpoint or station point (depending on which way they did it) of a space elevator would be between the inner and outer belts. You'd have to go through the lower belt for damn sure, and if you want people to live through that (well, and not die of cancer at the very least) you have to shield them.

However, the outer and inner belts both offer a good deal of protection from things like solar wind and flares.

I like the launch loop idea, but feel like the elevator requires little more than mass production of something on the edge being able to be mass produced (which you'd do on site, not shipping 1km length spools out there :wink: ), particularly if something like this (http://www.eurekalert.org/pub_releases/2007-12/uoc--nbs120707.php) takes off. I don't know enough to guess though. For example, how much power is required for station-keeping? 

As to why we'd go to Mars? Well, the Moon is to Mars as Mars is to Jupiter, particularly the moons. There's only so much you can learn by continually looking inward.

Pff, NASA's out privately (http://www.virgingalactic.com/) operated space missions are in!

Oh, and I'm sure someone could be able to get some guys like Gates and thelike interested in the vast quantities of dense Velspar that are awaiting being refined to pure MONEY!.

Pfft... Carmacks sub-orbital plans look much more interesting (http://media.armadilloaerospace.com/2008_02_24/6-pack_apogee.jpg)!

Meh, there's not that much cash in mining, unless they get corp members to front them a good mining rig.  Otherwise it's a better use of their time to just run agent missions.

I'd be surprised if there were any agent missions left in Sol 3 and its moon for said people.
They seem to have pretty much exalted their reputation with everybody they can get money from.