Just imagine the cost....
Putting a washing load on Mars might be a VERY expensive proposition.
... in an air volume limited environment.
To quote Howard the Duck, "This does not bode well....!!!!"
Checks for dry clean only label.... check.
Top space boffins say that they have discovered signs of ice on a second asteroid, indicating that water may be commonly found throughout the asteroid belt - which would be good news indeed for humanity's future in space, as well as offering an intriguing insight into the remote past of Earth. It was announced in April that …
I recall reading a book (well, booklet really) by a Cambridge physicist where he applied his knowledge and experience of physics to definitions of life as penned by philosophers, biologists, ... and so forth.
His remarkable conclusion: whatever definition of life and living things the inevitable conclusion is that the universe is a life-form. Now that is a big, awesome, powerful thought no?
I am totally out of touch with this stuff. Does anyone do a good program that will let me figure out delta-V fortransfer orbits -- not for actual navigation, just fun? I am not at all convinced that asteroidal material is particularly cheap f.o.b. Clarke orbit ... it would take a lot of infrastructure
Warning! Rant on a pet peeve by someone with a long term deep interest in planetary science and exploration ahoy! There's a reason this topic is absolutely verboten over at the very, very wonderful http://www.unmannedspaceflight.com...
The relevance of this finding to humanity's future is nil, zero, nada, sweet FA. The cost and risk of human spaceflight beyond LEO is always vastly underestimated by the, and I'm sorry to say this, Star Trek fanboys who get all fappy about stories like this. Sorry, chaps, but it's never going to happen. Why not? Simple: physics, biology, and engineering. Consider that the superficially simple task of an automated Mars sample-return mission is no more than a pipe-dream of newly minted grad students on attachment at JPL, UA, etc. Why is that? Well, to get (say) a kilo of rocks back from Mars, you need - in reverse order:
a Hayabusa-style vehicle capable of returning from an orbit outside earth's, carrying a reentry capsule. This is, relatively, easy; Hayabusa worked, just (although note that Japan's space program is capable of roughly one such mission per decade.) (Yes, the Russians - or rather Soviets - did automated sample return from the moon forty years ago, but that's a very different case, as we shall see.) Secondly, you need a way to get the rocks from the surface of Mars to the return vehicle. Obviously it would be wildly inefficient to have the transfer vehicle do anything than orbit Mars waiting for the rocks to come up and meet it. OK, so that's a MRO-class spacecraft (you don't want to have something orbiting mars for four years or longer without hanging a few imaging spectrometers, hi-res cameras and what not off it.) Let's be optimistic and call that $1500m. Oh, and this vehicle will need to talk back to Earth; we don't currently have a dedicated telecoms orbiter at Mars, and one's badly needed already (with MRO, Mars Odyssey and the European Mars Express s/c all in orbit to relay data from the one surface vehicle still operating (the Opportunity MER vehicle.) Curiousity, aka the nuclear-powered, laser-equipped uber-rover planned for launch in 2011, will hopefully soon be adding a torrent of data to the existing b/w demands. There are already occasional connectivity outages for a few days when one or other of the orbiters trips into safe mode, as they do from time to time. Although Oppy is already far beyond it's 90 day nominal mission (surface ops began in Jan 2004), MSL - if it lands successfully -- can be expected to function for many years, thanks to it's long-lasting RTG nuclear power supply (as used on the Voyager probes, for instance, which are both still operational more than 30 years since they were launched.) So we probably need a dedicated comms orbiter, too: another $1500m, though the Sample Return share of that would be smaller, let's say $500m.
Now comes the tricky bit. You need a booster to launch that small 1kg payload from the surface to Mars orbit, with the ability to autonomously rendezvous and dock with the return shuttle, then transfer the payload to the mothership. Nothing like this has even been demonstrated. Remember that Mars' atmosphere, though thin, is easily dense enough to be a significant factor in the ascent booster's design. (This problem is nothing like the Soviet lunar return vehicles, which simply aimed at roughly the right part of the sky and launched when a simple mechanical timer expired.) You don't need an Atlas-sized vehicle, but you certainly need something substantial. It'd need to be liquid fueled, which adds enormously to the complexity and risk of the design. (Consider the size and complexity of terrestrial launch pads. ) You don't need to rebuild the Cape or Baikonur on Mars, but neither are you looking at a glorified Estes solid-fueled fire-and-forget system. Again, nothing like this has ever been built, much less demonstrated to function. What's more, the thing has to be launched from earth, transit to Mars, land *very precisely* (see below), and then reconfigure itself from a lander to a state where the ascent vehicle's ready to go. Getting that for less than $5B would be very good going indeed.
And finally, you need something to go out and collect some interesting samples. The ascent vehicle would also have to rendezvous with the cache of samples when the rover's done it's scavenging, hence the requirement for a veyr accurate landing. State of the art Mars EDL systems would be the Skycrane system that will be first used to deploy MSL. If you would really like to bake your noodle, check the offficial animation of this thing (and remember, it may look like a spatchcock Heath Robinson affair to you, but hundreds of extraordinarily smart people have been thrashing their brains for a decade to come up with this: http://www.youtube.com/watch?v=E37Ss9Tm36c Everytime you find yourself saying "What?! Why the hell are they doing it /that/ way?!" remember they are much more clever than you are, and they have spent much of NASA's Mars SDS budget for the next decade on designing and building this thing; there are very good reasons for everything that makes you think "eh??" , though of course I encourage anyone thinking that to dig into what those reasons could be. You might find it interesting.)
Right so where were we - ah yes, a (successful) EDL for the ascent stage and and launch pad, with pinpoint accuracy; that gives you perhaps a 50km drive from the rover's standoff position to the site the ascent vehicle lands. Now a 50km drive *after* extensive sample-gathering traverse pretty much guarantees you can't rely on solar panels. Although the MERs have done extraordinarily well, waiting five years for one to limp slowly towards the ascent stage, with the high risk of an atmospheric storm dumping dust on the panels and killing the rover early, is just not acceptable. (It's OK when it's just a rover, but for MSR it's a vital component of a much larger and more expensive multi-vehicle system.) Ergo, you need RTG power. Setting aside the embarrassing and hopefully temporary shortage of usable Pu to build such a thing (NASA have about 1.5 missions' worth left in stock and the US doesn't make the stuff any more, so they're reduced to begging the Russians for supplies; oddly enough, the Russians aren't exactly awash in it, either. (No, they can't just "take it out of power stations or bombs".) However, let's assume RTG power is available. As the skycrane design work will be as close to "COTS" as Mars-bound hardware ever gets by the time this hypothetical mission launches - 2025, say, though that'd be /extraordinarily/ optimistic -- we can get the fetch-and-cache rover for a bargain knockdown price, say $1250m.
So you're now looking at a minimum of four launches and five separate vehicles (counting the ascent stage and it's lander-autonomous-launch-pad as two, which they will in effect be.) Here's how the components stack up:
Sample caching rover: $1500m
Launch pad /
ascent stage: $5000m
Return shuttle: $1500m
Telecoms orbiter $ 500m
There's one more factor to take into account. The world is not currently awash with experienced astronautical engineers capable of designing and building systems like these. For MSR, all these components need to be designed and built in parallel, as part of one over-arching metaproject. The scarcity of resources means you must compensate by (1) even more obsessively rigorous design and progress reviews, and (2) not trying to build and fly everything at once. (You don't want to end up with a redundant launch pad / ascent stage if the caching rover ends up lithobraking, i.e., adding a smoking crater to Mars' extensive inventory of holes in the ground; you probably want to hold off launching each stage until the previous one is past as many of it's critical points as possible.) This staggered design/build/launch process gives you at the very least a 15-year-long project. (Steve Squyres' Athena project which eventually became the wildly successful Mars Exploration Rovers can trace it's genesis back almost 20 years. Doing MSR in as little as 15 would be a gigantic achievement in itself.) If you're lucky, call that another $1500m on top.
Congratulations! You've spent four times more than the single most expensive Mars mission, and you have a kilogram of, hopefully very interesting, rocks to show for it.
Now imagine doing it with humans. You need a crew of at least three, plus all their consumables, life-support, and to include the conisderable costs of man-rating kit like this.
Let's make a hand-waving assertion that you could do a manned version of such a mission for $50B. (I think that's a vastly over-optimistic estimate, but it'll do.)
Now remember that if we did this crazy thing, and it all worked, and we got the crew back safe and sound with their own cache of rocks and snapshots, there's NOTHING LEFT. All the bent metal has flown, and been used up, and is gone forever. Imagine trying to build kit like that *off earth*, from scratch. First you need to mine your iron ore,..
And that's why Star Trek is science fiction, and will always be. Human colonisation of the solar system, flights to the asteroid belt or indeed anywhere else are pure fantasy. It's never, ever going to happen. (And for that reason I don't think we'll go back to the moon, either; what's the point, unless it's a stepping stone?)
> "Very little push would be necessary to bring it to the thirsty satellites that we rely on for comms, navigation, observation and so on."
No, but you'd need a pretty big push to slow it down once it got here, so it didn't:
1. Get snagged by the atmosphere and burn up
2. Plummet to the surface like a jumbo hailstone
--- --- or --- ---
3. Zip on past on a cruise to a less useful part of the Solar System.
The amount of energy required to reduce an object's relative velocity to zero is equal to the square of that velocity.** Even a small ice tug (say, 100 tons, give-or-take) moving just a few kilometers per second would need a pretty big reaction engine to slow the cargo down enough for insertion into a stable orbit.
** For purposes of discussion, zero relative to the orbital receiving station, at the point along the ice tug's path tangent to the receiving station's orbit.
So has someone done the maths to prove that directing ground based lasers onto satellites for an extended time wont exert enough light pressure to counterbalance them spiralling into the Earth?
I would have thought this was an easier and cheaper solution than collecting ice from millions of miles away.
"Proof-of-concept missions have shown that there's no technical obstacle to sending up robotic refueller craft, but the costs of lifting payload up through Earth's thick atmosphere and deep gravity well are so vast that the economics of satellite refuelling from the mother planet are dubious."
Cost of refuelling existing satellite: x
Cost of putting a replacement satellite in orbit *without fuel*: y
Cost of putting a replacement satellite in orbit *with fuel*: x+y
Ergo, surely this statement is wrong. It will always be cheaper to refuel an existing satellite.
In fact, if you had a standard refuelling system and one mission refuelled several satellites, you could make it even more efficient.
Good job of turning an article about asteroid resources into an exposition of manned direct surface to surface flights to Mars using chemical rocketry and programmable RC cars, but that's a bit of a worse case scenario, not realistic as you say but not really what this is about.
The find is significant because it now means that we could refuel ion-drive ships in the Belt rather than waste energy sending up all that reaction mass from Earth, and install drives on the 'roids and push them into closer orbits. Then get e.g. the Chinese to render these flying mountains into refined metals and we can stop strip mining down here, amongst other things, plus we make sure we don't run out of stuff to build more spacecraft out of (a real risk otherwise!). In fact, with both water and raw materials in some kind of near-Earth orbit we can finally start setting up some serious space-based industry. Refuelling comsats is just the first step.
Naturally the only ones who will go beyond LEO or maybe the nearby Lagrange points in the short to medium term (centuries) will be robots, bringing stuff back to us. In order for humans to colonise space in significant numbers we really need a different launch system, alas.
RotM, because they are the future.
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