Tuesday, February 13, 2007

Bringing Home the Dirt

For a successful technology, reality must take precedence over public relations, for nature cannot be fooled.~ Richard P. Feynman

The idea of sending a probe to another solar system body to collect samples and return with them is getting closer to reality, if the European Space Agency has anything to say about it.

It's not that we haven't gotten samples before. The Apollo missions brought back bunches of rocks from the moon, which are still being studied. Stardust returned with tiny little particles of comet and interplanetary space dust. It's cousin with the reverse-installed sensor, Genesis, returned with solar wind samples but crashed in the desert, leaving the science team with the daunting chore of reassembling and identifying the sample collectors. To date, it appears that some data will be saved, but how much is open to speculation.

Japan's Hayabusa probe may be bringing back some asteroid samples, but no one is quite sure at this point whether the sample was ever gathered. After a reasonably straightforward trip to asteroid Itokawa, things went awry. Mission controllers thought the satellite did its bounce-and-collect trick at least once and possibly twice, but returned data was ambiguous. It started on its return, which was projected to be this year, but something then went terribly wrong when fuel began leaking which had the effect of spinning the probe and losing maneuvering capability. Just to make matters nearly impossible, communications with the satellite were lost.

It's hard to find anything on the current status of the mission, since links to the Hayabusa web site all seem dead, but at least one badly translated summary tells us that contact was regained in 2006. Hayabusa is still due for a 2010 return to Earth.

{Whether the Japanese will have a space program operating to welcome it is somewhat up in the air as a lunar mission and a Mars mission have already been scrapped.)

Sample return missions, therefore, are no piece of cake. Of course, what everyone really wants is some good solid Martian dirt. If we could get hold of a nice little core sample (better yet, several nice little core samples), we might be able to determine once and for all if Mars ever hosted living organisms. It's no surprise, then, that the ESA is focusing on such a mission.

There are a couple of proposed designs that involve trying to hit Phobos first. Phobos makes a good target for a couple of reasons. First, it's easier to land and take off from a body with minimal gravity. Secondly, Phobos is very old, possibly made up of the primordial stuff that clumped together to make planets. That by itself makes the potato-shaped moon an inviting target.

One of the design, which itself has two possible permutations comes from Russia. The program is called Phobos-Grunt (grunt means “soil” in Russian, in case you're wondering; I certainly was), and the British, the folks who gave us the Beagle pancaking into the Martian landscape, has one tentatively called Astrium. The two approaches are rather different solutions to the same problem.

The Russian spacecraft, which is still bouncing between two designs (one with ion propulsion, one using conventional means) would land as one unit, poke around on the surface and conduct some experiments, grab some dirt, and return to Earth, presumably in the normal parachute-enabled manner. The proposed launch is some time in 2009 and looks set to go, although still having to decide between two propulsion models would make a launch in two years look like a tight schedule.

The British proposal would launch in 2016. This satellite would use ion-propulsion to get to Phobos and dispatch a probe to land on the moon's surface. The probe might do an experiment or two, but its main mission is to glom a little Phobos dirt and return to the main vehicle. That vehicle then returns to Earth and once again ejects the probe which comes to Earth and – here's the funny bit – crash lands, with no parachute or retro-rocket firing. I'm certain that the probe is designed for such a landing, but somehow it doesn't inspire one with a huge amount of confidence that we won't have Phobos-dirt scattered around a desert landscape somewhere.

Now, readers of this bit of the blogosphere might be aware that one of my concerns is developing methods for manned exploration with an eye toward colonization, to give humanity a chance at surviving its best attempts at messing up its home planet. But, sample return missions are very important, too. To begin with, the best way to find out a great deal about a place you may wish to visit is to study actual pieces of it. Also, it's the most economical way to continue to expand our knowledge of our immediate corner of the Milky Way.

So, let's go get some grunt.

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