Because it’s a slow news month, everybody’s talking about this article here which shows the allegedly-startling news that weightlessness is bad for you. http://news.yahoo.com/s/ap/20100821/ap_on_sc/us_sci_space_weaklings;_ylt...
This is hardly a surprise, we’ve got 49 years of data to that effect, but I guess some people haven’t been paying attention. In any event, for those of you not in the know, our bodies were designed for gravity. We live, work, play, swim, and die in “One G.” Our systems are based around resisting gravity. If you take us out of that, the normal systems the body uses to maintain itself become ineffective.
The first Skylab mission in 1972 discovered a substantial amount of calcium loss in only 28 days in space. Longer missions on Skylab and on the various Salyut stations verified this, and showed a substantial amount of muscle wasting as well. Valeri Polyakov spent well over a year on Mir http://en.wikipedia.org/wiki/Valeri_Polyakov After which he was weaker than a kitten. A standard hitch on the ISS lasts six months. After half a year in space, most space travelers can only barely walk when they get back to earth. Massive amounts of exercise in weightlessness have been tried to stop these deleterious effects, but they can only slow it, not stop it.
True, therapy and rehab help quite a bit once one returns to the ground, but the bottom line is this: The body never fully recovers from such long-term spaceflights.
Most plans for a manned trip to Mars last three years, with only a month or three on the planet itself.
Three years! Six times as long as an ISS tour of duty! Can you imagine what that’d do to the crew? Frankly, I’m pretty sure they’d be crippled for the rest of their lives.
Ok, now let’s take a step back here:
Plans for missions to Mars are basically following something like the Apollo concept: Go with two or three people, land, collect some rocks and some photo ops, and come home again. While this is swell for the moon, and borderline-affordable: about a half billion dollars per mission in 1970 dollars (Adjusting for inflation, $2.8Billion today, or slightly less than the cost of three Space Shuttle launches), Mars is going to cost, conservatively, twenty times as much. That’s just way too much money to get that little bang for your buck.
But maybe we’re going about this all wrong?
Most people assume we *need* to go to Mars. I personally don’t see this as a need, there are other more interesting places to visit, *all* of them easier to get to than Mars, however I do think the idea of a trip to Mars is super cool, so I’m all for going, though I don’t see it as a moral imperative as many do.
Many people assume that we *need* to colonize space, me among them. The most obvious location (Not necessarily the best, mind you, http://www.republibot.com/content/mars-or-venus-which-better-home-humani...
but the most obvious one) is Mars.
The general assumption is that exploration comes first, and colonization comes at some later date. Well, we all see how well that went with the moon: it’s been 38 years since we left, we never got that moonbase, nor any other cool stuff. The fact of the matter is that as long as governments are running space programs, you’re basically only gonna’ get one shot at things, and if you don’t take advantage of it then, it can be two or three generations, or more, before anyone gets around to trying it again, if ever. This isn’t just a space thing, either: It’s been half a century since anyone bothered to visit the bottom of the ocean http://en.wikipedia.org/wiki/Bathyscaphe_Trieste
Now on top of the engineering and logistical and budgetary problems involved in a trip to Mars - all of which are pretty daunting - there’s also the substantial health problems. In essence, you’re asking your astronauts to throw away their health and consign themselves to a life of decrepitude in exchange for a month or so on the fourth planet. That doesn’t mean there’s not a lot of people who’d volunteer for the trip - I’d line up for it myself - it simply means that in human terms, it’s a lot to ask for a comparatively small payoff.
But what if the trip was one-way?
I mean, we’re effectively asking the crew to throw away their lives anyway, right? What if we *Combined* colonization and exploration into one mission, rather than bringing them back home again?
Think about it: Let’s assume it takes one hundred pounds of spacecraft for every pound you put on Mars, and a thousand pounds of fuel for every pound of spacecraft. Assuming a Skylab-sized ship, which seems reasonable to me, then we’d be looking at 100,000 pounds of fuel (These aren’t authoritative numbers, they’re just to illustrate the problem as a whole). Half of that weight, obviously, is fuel to bring the ship back home again. If, however, we’re not interested in bringing the ship home again, we only need half as much fuel, reducing the size of our ship by half, *OR* we can use all the fuel and double the cargo capacity of our ship. That’s more efficient, right? And since we’re not planning on bringing these people back, the trip is shorter - one leg, only about nine months in weightlessness, followed by a long life in a low gravity field. Martian gravity might be bad for you as well, but it’s more or less *got* to be better for you than no gravity at all, and this is a great way to get decades of firsthand biological data about that from one mission, rather than piecemeal information from a dozen shorter missions. And with less in-flight time, the risk is smaller, far less likelihood of a solar flare or malfunction killing everyone in transit.
And what of the lander? You need something to get down to the surface and back up again. All things being equal, you’d need something about three times the size and capacity of the old Apollo LM to do it, so say 100,000 lbs, though actually it’d need to be considerably bigger since your crew would need to live and work in it for a month or so on the surface. And of course two thirds of this weight would be the ‘descent stage,’ the engines and fuel you’d need to land the thing. The remaining third would be ‘ascent stage,’ and more than half of that is gonna’ be fuel, which leaves you - by liberal estimate -10,000 pounds (Including crew) that you can take back to orbit. Tiny, and presumably you’d discard *that* in orbit once you‘ve gotten the luggage out, rather than hauling it all the way back to earth.
Conversely, if we intend the lander to land *only* it’s simpler to design, much safer, and vastly, vastly, vastly more efficient: Suddenly 33,000 thousand pounds of the lander are all useful space. In fact, we can make it simpler still: we’ve got a hundred-ton spacecraft, right? Why not land the whole darn thing? Our entire ship, once it detaches from the drive section, is a hundred-ton lander, of which 33 tons - equivalent to more cargo capacity than a shuttle flight! - is useful space!
“So how are they gonna’ live?”
Well, we’d launch cargo rockets for a decade or so prior to the mission, landing supplies and construction material son Mars, and using those missions to test out the reliability of our navigation and engines and whatnot. When the first manned expedition lands, they’ve got all this gear there waiting for ‘em: Plenty of stuff to build a home, and more besides to prospect for useful stuff with which they could expand their home. Subsequent missions would bring more people and more supplies.
It would be a harsh life, but it is theoretically possible to ‘live off the land’ on Mars, given the proper equipment and precautions. Soil could be processed to grow plants, there’s plenty of water and methane, oxygen can be prized from the soil or electrolyzed from the water, and there’s no shortage of iron. And if it turns out to be possible to have children on Mars - a subject of much debate - then you’ve got a self-sufficient colony, which is the goal of *every* colony, and more information than the folks at NASA could ever hope to flense in a lifetime.
And even if it’s not possible to have kids there, you’d have a bunch of people on Mars sending back lifetimes of information for the same money that a ‘round trip ticket’ mission would cost you.
It seems pretty obvious to me which is the wiser choice.