Apr 26 2006, 04:48 AM
He makes a very good, sour case where manned Mars expeditions are concerned (and also regarding the serious limitations on using lunar polar ice for ISPP on lunar missions). I do note, though, his howlers toward the end regarding unmanned astrobiological studies of Mars:
"Yet even within the JPL-led Mars Exploration Program (MEP), there are aspects that cause wonderment. The principal goal, motivation, and emphasis of the MEP is the search for life (past or present) on Mars. The adoption of this goal, with its innately very low probability of occurrence, introduces several anomalies in the logic of it all. Life requires liquid water, and liquid water can only exist well below the surface. Similarly there are no organics on Mars—at least not to one part in a billion. Yet we continue to hear about the MEP searching for organics and near-surface liquid water, and developing life-detection instruments."
The difficulty in finding surface liquid water on current-day Mars, of course, has absolutely nothing to do with the search for fossil Noachian life -- which has always been the main goal of the life search. And we only know that organics are missing on the surface, where oxidants and UV can destroy them -- we'll be looking for them mostly inside rocks. Moreover, judging from the recent conclusions of numerous researchers, even where present-day life is concerned we may not have to look that far underground (or inside rocks) to find both intermittent small amounts of liquid water and environments that can shield organics from destruction.
But, to repeat, he does a very good job of portraying just how staggeringly difficult any manned Mars expedition will be (even utilizing ISPP on Mars, which he thinks is entirely feasible).
Apr 26 2006, 01:21 PM
Here's my prediction: there *will* be manned missions to Mars well before that - but they won't land. They'll either stay in orbit, or hunker down on Phobos. From orbit, they'll link up with unmanned surface vehicles, and recover samples using both aerogel and by manually docking with and retrieving small packages launched from the surface, thereby doing away with most of the problems associated with unmanned sample return missions. All this will be done with semi-commercial space station technology, and a CEV re-entry vehicle. It'll be done this way because it's cheaper, and it'll be sold as being a 'first step' and one which will be biologically responsible towards both Earth and Mars.
I'd see a Mir-class core with two TransHab modules and a CEV, launched on a low-energy trajectory by whatever big booster's upper stage is available by then - and perhaps some radical departures in terms of orbit insertion and TEI rocketry, with perhaps the use of SRB-derived solids for MOI and ion engines during the cruise phase. It might well be the case that an unmanned precursor mission would be flown into Mars orbit, to act as a technology demonstration and to provide a safe haven and resource dump.
Something akin to this architecture would cover most, if not all, the bases, and would use the strengths of unmanned spaceflight to bolster the weaknesses of manned, and vice versa.
Apr 27 2006, 12:25 AM
I'm inclined to agree with you that we will see this kind of manned Mars mission for some time before we see actual manned landings on the planet, simply because we won't want to contaminate the planet with the tidal wave of Earth microbes inevitable from any manned landing -- and because a local manned Mars-orbiting command station for unmanned robots would allow them to explore the surface at tremendously higher speed than those commanded from Earth.
But all the huge problems with manned Mars expeditions mentioned by Rapp apply every bit as much to this kind of mission. In fact, one of them is more serious -- without landings, you can't use ISPP to refuel your manned return ship, which Rapp regards as a necessity if we're to have any chance at all of ever flying manned Mars expeditions. (However, you could land unmanned ISPP "tankers" to land, manufacture fuel, and then launch it back into Mars orbit to refuel the manned ship there. It's even conceivable that you might be able to dig up accessible water ice inside the Martian moons, although I think the odds are very much against it.)
Apr 27 2006, 02:54 AM
Dare I say that by the time we are able to land really smart robot
explorers on Mars, will we really need to have humans hovering
overhead on Phobos? Why not just send more smart and less
resource-intensive robots there as well?
Apr 27 2006, 07:52 PM
The big advantage of not landing is that you need to haul along much less in the way of food for hungry rocket engines! Not to mention the sheer difficulty of actually building a manned lander and ascent vehicle - I'd not be surprised if actual manned landings end up being 'one-way' to a pre-established resource cache/base, which really does imply that most of us won't be around to see it happen.
Apr 27 2006, 11:01 PM
Uh-uh. The BENEFIT of landing on Mars as opposed to just orbiting it is that you can use ISPP to refuel those hungry engines completely -- not just for the delta-V needed to lift back into Mars orbit, but also for the additional delta-V needed to get out of Mars orbit and back to Earth. All Martian-ISPP plans use that assumption -- and even Rapp thinks that Martian ISPP (unlike lunar ISPP) is feasible and in fact necessary whenever we do finally fly manned missions.
As I said, even if we just leave the manned crew in Mars orbit, we'll probably have to have landed unmanned "tankers" previously on Mars to manufacture the propellants for the manned ship to blast out of orbit and back to Earth -- which would then use part of the propellant they made to lift themselves into Mars orbit to rendezvous with the manned ship and thus refuel it. Do this, and neither the manned ship nor the tankers needs to launch ANY load of propellant to escape velocity from Earth; the tankers just land on Mars directly, and the manned ship aerocaptures into Mars orbit -- after which they all entirely utilize propellant Made On Mars.
Apr 28 2006, 12:27 AM
It stands to reason that by 2040 propulsion will not have changed much, thereby making MOI, Mars Descent, and Mars Ascent and Return roughly as difficult as we imagine them to be today.
However, it also stands to reason that by 2040 we will have substantial experience in building and surviving in Lunar shelters for extended periods of time. If our ability to support men on extraterrestrial surfaces has outstripped our ability to *return* men from extraterrestrial surfaces, would it not be a good idea to simply ask for volunteers for a one-way mission?
We could send several habitation modules and supply stores over a period of several years, and then finally land a one-way party of 4-6. Every 26 months we could continue to send supplies until...well, they die or we pick them up years later.
It sounds crazy to think of one-way missions with regard to manned exploration of space, but really, in all previous Ages of Exploration one-way missions were an accepted baseline. Post-Columbus, for example, the goal was in colonization (and exploitation, obviously), not in simply traveling and returning.
Apr 28 2006, 06:13 AM
Except that the colonists in those days didn't think of their one-way trips as possible suicide missions -- if they were aware of the risk, they thought that the personal economic gains for themselves outweighed them (especially true either if they were desperate poor or if they were underoing religious or political persecution here. How many volunteers are you going to find for Mars expeditions with a serious chance of dying for nothing more than some science data that could be obtained in less risky ways?
Apr 28 2006, 06:29 AM
QUOTE (BruceMoomaw @ Apr 28 2006, 06:13 AM)
How many volunteers are you going to find for Mars expeditions with a serious chance of dying for nothing more than some science data that could be obtained in less risky ways?
Seriously the problem isn't the volunteers themselves but the whole combination of the type of risk averse organisations that space exploration requires and society itself which finds the idea of a suicide mission for the sake of scientific discovery unacceptable while happily embracing social\economic\environmental standards and policies that kills thousands daily.
This isn't a particular rant against any particular political point of view but it is true that societies are happy to live with sensible balances in policy\standards that lead to some collateral damage (think "road safety" for example) while finding the idea of a single stranded human victim abhorrent.
Apr 28 2006, 08:40 AM
Oh, I have no doubt you'd find SOME volunteers -- after all, there are still plenty of astronauts willing to fly on the Shuttle despite the fact that there's approximately 1 chance in 50 that it will kill them every time they fly on it. But when you combine that with the other huge disadvantages of manned Mars missions -- the staggering expense in any case, and the fact that manned Mars landers will instantly contaminate the one thing on the planet that might be worthy of their study -- the plan becomes even more implausible. (I hope no one here is falling for Robert Zubrin's bulging-eyed twaddle about the need to set up a Rival Civilization on Mars -- even Ben Bova has had some acid things to say about that idea. If we're going to set up a Rival Civilization anywhere in the Solar System, we might do best to set it up -- eventually -- on Ceres.)
May 12 2006, 03:16 PM
"Race to Mars", a 3-hour miniseries on The Discovery Channel about a manned
mission to the Red Planet in the year 2030. Apparently the US and a few other
nations were spurred on by China's space ambitions. The series comes out in
Read more here:http://www.msnbc.msn.com/id/12743183/
Quotes of note:
The $18.1 million ($20 million Canadian) production — which covers "Race to Mars," an added one-hour faux-documentary retrospective by the flight’s “astronauts,” plus "Mars Rising" and the Web site — is being billed by Discovery Channel as the most expensive science television project under way in 2006, though program managers are hoping its realism and detail will prove worthwhile. More than two years were spent in preparation for filming, including meetings with Mars and spaceflight experts, Lewis said.
“One of the important goals, frankly, for us was to see if we could start to generate public interest, public excitement about human exploration of space again,” Lewis said. “It’s obviously something that really hasn’t fired people’s imaginations for a long time. … Our feeling is people are willing to be inspired again.”
May 12 2006, 07:21 PM
A manned mission to one of the moons of Mars would be a good starting point, as both Phobos & Deimos are suitable gateways to extensive Mars exploration (although an unmanned probe should find out how deep the regolith/dust layer is on those Moons
... and make detailed maps to locate suitable landing areas).
A base on Phobos would provide links with unmanned spacecraft on the red planet and even down-to-the-surface sorties to points of intrest by a manned shuttle. This would be the best way to explore Mars as any long-distance surface trip would be too dangerous in way to difficult terrain ...
I've read Dr Zubrin's books on Mars exploration but I'm not optimistic to see a manned mission to Mars in my lifetime ( turning 40 this year ...
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