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More to add to that. How does the human mission stack up?
Assumptions:
Mission cost: $30 Billion (MarsDirect)
Time to take photo: Half a day (travel to site, setup for EVA, etc)
Total mission time: 2000 man-days on the surface (four man crew for 500 day mission)
$30,000,000,000 * (0.5/2000) = $7,500,000
So the costs are comparable, even assuming a generous half-day for an astronaut to get a decent image. Interesting. I guess another large assumption is that all uses of an astronaut's time are equally valuable. What's a good photo worth compared to knowing the chemical composition of a rock? I suppose we stick to the economist's doctrine of ceterus paribus, all other things equal, for now.
To make the exercise valid for Mars exploration we need common denominators. Distance traversed, science payload, samples returned. For cost we can use either a simple total cost or cost per kg. if you can think of a better measure, than by call means suggest it.
The cost per km traversed, cost per kg of returned sample, cost per image - would all make sense.
Exploration cannot be measured in kg.
Cost per image is a good one that caught my attention a few days back whilst cruising wikipedia:
http://en.wikipedia.org/wiki/Image:Vict … e-Mars.jpg
This image represents 3 weeks solid work for one MER.
$400,000,000 * (21 days / 1500 days total mission) = $5,600,000
Pretty expensive shot!
I think it sounds great - but you still need to overcome the hurdle of getting adequate return within a reasonable timeframe. Yes, I know the argument that if we can terraform the land then it will probably be worth 100x, but at what cost and in what timeframe? You need to find a way to make double-digit percentage gains (per annum) on a multi-billion dollar seed capital, and that return has to come in within about a decade, so terraforming is certainly out, as is mining.
Anything less than 10%pa within 10 years is not going to wash with private capital.
By the way, Terraformer, don't stand around then. Go claim your own bit! Or invest in the consortium yourself. That way it won't be a bunch of elite Bill Gates types who claim the planet, but rather you yourself, along with anyone else who gives a damn. "For all mankind."
No resupply except Soyuz from 2009-2015? With any luck SpaceX and the Dragon capsule will come to save the day... and hopefully human spaceflight in its entirety.
Thanks, I guess I'll just wait for a bit. No worries.
Sorry Chris Columbus, you cant sail west, you'll fall off the end of the earth.
Sorry America, you can't be independent, it's against British law.
Sorry Mars, you can't have any of your own planet, it's against an anachronistic treaty that was signed before man even landed on the moon.
Sure.
Hi, I'm relatively new to the forum and can't seem to get a profile pic uploaded. I've made sure it is under 80x80px, under 8kb, tried a variety of different image extensions (.jpg, .gif) but it still doesn't work. Is there anything obvious I am doing wrong?
Here's an idea to sex-up the public perception of a Mars mission - Imagine four spacesuited dudes tearing across some rusty Martian plain on dirt-bikes - it's the kind of thing that would capture the public imagination like nothing else.
I also think they would make a very effective transport system. Zubrin's Case For Mars budgeted 800 kilos for two open rovers. You could easily build FOUR dirtbikes for about half that mass. And they'd be fast, light, maneuverable, easy to maintain, and simple to develop (all it would take would be a CH4/O2 engine and a separate tank for the O2).
(obviously this would be in addition to a pressurised rover - you won't be going for long-distance trips on bikes)
I'm also an Aussie enthusiast, will you be going to the MSA convention in Adelaide?
I did a quick search on this and came up empty handed - sorry if this has been discussed before!
Assuming that a MarsDirect-style mission is undertaken (with artificial gravity to minimise the exposure to zero-gee), is there any reason you couldn't get away with a relatively normal toilet in the Hab? I'm thinking something like what they have on airlines. For the couple of weeks (tops) that astronauts are exposed to zero-gee, they could just rough it - collect it in disposable bags, like was done in Apollo. Considering the vast majority of mission time is spent in 1/3 gee, this would not be too bad. And it'd be great for the morale of the astronauts to be able to use a normal toilet for the majority of the mission.
If the ERV is to travel in zero-gee, then it'd obviously need a zero-gee toilet, but it will necessarily be a separate system to that on the Hab anyway.
Comments/criticism welcomed, as always.
Would a MarsDirect ERV need two sets of LOX and H2/CH4 tanks, or would one set that gets refuelled onsite be sufficient?
*After landing and fuelling the ascent tanks, the descent tanks could also be filled for general base use (powering rovers, backup generators, etc)
*The ascent engines could be separate to the descent engines, eliminating the need for a restartable engine (but with the obvious disadvantage of additional weight)
Likely requirements:
1) Compact (as small as reasonably practicable)
2) Low in mass (both the reactor and subsystems)
3) Able to function for years without any significant maintenance
4) Able to operate remotely from any Earth-bound operator.
I would add another -
5) Able to self-deploy and self-start
...since many mission designs, most notably MarsDirect, call for an ERV powered by a reactor to precede the manned craft. I'm sure the startup of many of these systems is quite sophisticated.
On the other hand, solar would need no "starting", but it would be very difficult to deploy 100KW worth of solar panels
I wonder how much 100KW worth of solar would weigh?
Sorry- 200KW worth, because solar doesn't work at night.
Furthermore it's even more important to test if this rotation will counteract the effects of zero gravity on the crew.
How can it not? The body requires a modicum of force acting on it to remain healthy. Whether that force is from gravity or centripetal acceleration should have no bearing.
As for whether 1/3g is enough, well why not test it out in the process of going to Mars? Humans have survived longer periods at ZERO gee before. No point subjecting human subjects to months of boredom in space just to see what happens.
Meanwhile, should this topic be moved to another thread, since DRM 5.0 doesn't even employ a tether?
Humans don't actually need a global ocean or atmosphere to survive on this planet...
Ah, but we want one!!
Idiom - Like-minded? We can't even agree how to get there!!!
How we get there doesn't matter. What we really mean is "how do we get someone to decide to fund a mission"? The rest is just details. Nobody bags Apollo because it relied on critical orbital rendezvous, for example.
I for one would probably not like to live on Mars forever, at least not initially. But gee it'd be a great adventure to visit, and I certainly want to live in a world where someone is living on Mars!
*You're taking a digger on mission number one? You'll certainly need one eventually, but it's a lot of weight you can save while you're still working out the basics about living on mars. A digger will necessarily be much heavier than a pressurized rover (unless your digger is a very small unpressurized thing).
*As for gym equipment, most of your need for it will be in space, where the weight is non-existent (or only 1/3 if you have a tether) and you don't want to launch more than you need anyway.... so take along a TotalGym instead. It uses elastic resistance rather than gravity and our astronauts all come back looking like Chuck Norris! Perfect. And for cardio you can use an air-resistance cycle or rowing ergometer.
*MCP suit rather than pressure suit
*Fewer internal walls in the Hab - has advantage of creating a much more open living/working space
*Would they really need a washing machine? After all, what clothes will they actually have? Underwear, casual hab clothes, space undersuit... surely you could just wash it in the sink, old-school style. Ditto dishes.
*Instead of giving the Astronauts nothing but MREs, take very large bulk packages of ingredients that can be taken from as needed, take along a few pots and pans, and let them cook their own meals. Helps them stay sane, too.
Would it? I'm not so sure. There will be 10,000kg tension on this cable after all. Your thrust is only going to be a tiny fraction of that. And even if it does oscillate, how do you know it can't be controlled with micro-adjustments? Has this ever been tested?
Would a mars suit need to be heated at all? The temperature may be -60, but the atmosphere's only 0.005 bar, so what's going to convect the heat away from the suit? The astronaut's skin should supply a lot more heat to the suit than the thin atmosphere can carry away. So as long as they don't touch the freezing rocks with their bare hands (which they won't), they'll be fine, won't they?
You could control oscillations the same way you control coning motions during launch, or for that matter just about any of the new fighter jets these days that are inherently unstable - with computers making micro-adjustments many times a second.
I'm not talking about sending the ET up with a shuttle, but a second stage instead of a shuttle. And it'd certainly need a lot of work once it's up there to become a space-station per se (eg radiation shielding, life support, etc), but just getting a pressurised volume that large would be a huge achievement. As for the foam deteriorating, that's not structural is it? It would act as a great micrometeoroid shield. Surely the ET structure is capable of containing one atmosphere of pressure?
And assuming the Space Shuttle ET is in fact inappropriate, wouldn't the concept work anyway? If a new launch vehicle were developed to put not payload as such, but its large main tanks into orbit, that could be a cheap and relatively easy way to create large pressurised volumes in orbit.... or have I missed some fundamental flaw that has been addressed in another thread?
Doesn't the External Tank have something like 98% of the velocity it needs to achieve orbit when it is discarded? Sounds like an awful waste. If we could just give it a little extra push, we could use it for all sorts of great ideas (I believe this was one of Bigelow's original ideas for a space hotel). What about a Shuttle C with a small second stage?
I assume that ETs would be easy to pressurise. What about construction? joining several together and cutting windows, etc. Welding would work in space, wouldn't it?
I read recently that the Mars Society of Australia is developing a piezo-electric MCP suit called MarsSkin (see http://www.marssociety.org.au/). The fibres would be relaxed by passing a current through them in order to don and doff the suit. In other words, it only needs electricity when you're taking it off or putting it on. Sounds much safer.
Disappointing that Branson, with his own space airline taking off next year, would have a laugh at the expense of Mars's credibility.
EDIT:
Having read the site, I can't make up my mind whether they're mocking the Mars Society or not. They've clearly read a lot of Zubrin and the society's material. I suppose the bit at the end ("Virgle isn't real... yet") is a little hopeful. And hopefully any publicity's good publicity.
As far as mid-course burns, do we really need to do those until the vehicle nears its destination? The last week or two of the trip could be spent zero-G without much trouble.
Mid course burns can be achieved during tethered flight. For velocity changes in the plane of rotation, thruster bursts at the appropriate tangential vector each rotation would do the trick. And for changes perpendicular to the plane of rotation, a steady gentle thrust in the direction required would do. This could all be micromanaged by computer, presumably.
I think the worst bit about DRM5 is that it seems NASA is doing nothing but planning for decades on end. We've gone from the 90 day report, to the reworked MarsDirect, through a few more incarnations of the DRM, and now they've basically taken a carbon-copy of the ESA's ludicrous mission architecture and swapped Energias for Ares-Vs (which, to be fair, makes the mission slightly less crackpot). There is absolutely no prospect of any action being taken in the forseeable future which might make this, or any other Mars architecture, the slightest bit closer to realisation. What a shame.
