Paige was the principal investigator for "MVACS", which was the package of instruments that made up most of Mars Polar Lander's payload. For Artemis, he decided on a set of small hard landers - probably based on the design of the ESA's little 30-kg "Beagle 2", if that design works out well in its ground tests - and constructing a science team whose members consisted mostly of the members of the Polar Lander team, plus the team responsible for the tiny MUSES-CN "nanorover" that NASA was planning to have Japan carry to a small near-Earth asteroid on its 2002 MUSES-C sample return mission.

Development of the nanorover for MUSES-C was halted last year, due to both price overruns and weight increases - but most of the design work and a lot of the testing for it had already been completed, and it had been intended from the start for use on other worlds as well, including Mars.

Artemis' orbiting carrier bus would land three or four such landers (depending on their weight) on various interesting Martian targets - with one of them assigned to land on Mars' northern or southern polar layered terrain, just beyond the edge of the polar cap, to recover the science lost on Polar Lander.

Each lander's functions would in many ways resemble those of Beagle 2, even if a different engineering design is chosen for the landers. Each lander will carry a robotic arm that will dig up soil samples and also carries a drill to extract cores from nearby rocks which will then be ground up and fed into the lander's main experiment package, where they will be roasted at high temperature and the resultant gases analyzed to look for (among other things) organic compounds.

But the instrument used for this won't be a mass spectrometer as on Beagle. It would be MOD (the Mars Organic Detector), an instrument that would have been piggybacked on NASA cancelled 2003 sample return lander, which was developed by UC-San Diego's Jeffrey Bada to detect amino acids and "PAH" organic compounds with tremendous sensitivity by looking for their UV fluorescence. And MOD's functions will be combined with those of the "TEGA" instrument lost on Polar Lander.

Each oven would gradually heat a small sample of rock or soil powder to 900 deg C, recording the changing rate at which the sample's temperature rose as heat was applied, and the gases given off would be sent to sensors for oxygen, CO2 and water vapor.

Not only would this allow a measurement of the amount of ground ice or adsorbed water in the soil, but the procedure allows a surprising number of minerals to be identified, including many that could indicate whether Mars' surface was exposed to liquid water in the ancient past - especially carbonates. And since its soil is evenly mixed over the planet, this indication would be planet-wide.

Moreover, the CO2 and water sensors would use tunable-diode lasers sensitive enough to measure the trace isotopes of carbon and oxygen, and similar sensors would measure these isotopes in Mars' air - providing another indication of how much of Mars' original atmosphere has been swept into space by the solar wind, and how much of its original "reservoir" of CO2 and water stored in the ground remains.

These are all TEGA's functions - but the gases from the roasted sample would also pass over a cryogenically cooled "finger" on whose surface any traces of organic compounds would tend to condense.

Any "PAH" organics on its surface would naturally fluoresce under UV light, and a chemical that coats part of the finger would react with any amino acids to make them fluoresce too.

This technique could detect such organics in traces of less than one part per trillion - tremendously more sensitive than the instruments that the Vikings used to look unsuccessfully for any organic compounds in Mars' soil, and far more sensitive even than Beagle - as well as the UV organics detectors proposed for CryoScout and Urey.

Such organics might either be the fossil remains of ancient microbes or come from non-living sources as is the case for some meteorites - but their presence or absence would itself be of great importance in judging Mars' biological interest.

It's also possible that an add-on feature would allow some organic samples to be run through a miniature liquid chromatograph setup, which would allow MOD to distinguish "left-handed" and "right-handed" versions of some of the amino acids.

If a strong imbalance in favor of one "handedness" was found in the acids, this would be a very strong indication that they actually were the remnants of ancient Martian life.

Meanwhile, the tiny MUSES nanorover - a mere 1.2 kg and 14 centimeters long - would creep slowly away from the lander, supported on four wheels fastened to the rover's body by motorized hinged struts.

Despite its minute size, it would carry instruments much more capable than those on Pathfinder's "Sojourner" rover: a camera capable of magnified viewing, a near-IR spectrometer to analyze minerals, and an alpha-X ray spectrometer on the rover's rear to analyze rock and soil elements.

The swivelable struts would allow the rover to tilt its front or rear up to change its camera viewfield or plant its element spectrometer against vertical rock faces - and even to continue functioning perfectly well if it accidentally turned upside down. Also despite its minuteness, its designers think it could do a good job of crawling 10 meters or more from the lander, picking its way between rocks.

Finally, each of the four Artemis landers would also carry a copy of weather sensors like Polar Lander's, and a pair of small cameras on the end of the sampling arm which could be used both for panoramas of the landing site and for microscopic closeups of soil and rock - including a search for fine soil layering in the walls of a trench, such as Polar Lander had intended to do in a search for shorter-term shifts in climate of the sort that are thought to have laid down the large-scale layering of dust-ice mixture which makes up the polar layered terrain.

Of all these ten Mars Scout concepts, Artemis may have the best chance of being accepted. It uses virtually no components or instruments that haven't already been developed for other missions, sharply limiting its development costs; but at the same time it allows a really sweeping survey of different kinds of Martian terrain, with a particular focus on questions having to do with life (as well as recovering Polar Lander's lost science).

Like the other concepts, though, it will face stiff competition from the additional torrent of new Scout concepts that are bound to flood in when the actual official proposal for ideas goes out next year.

And, of course, only one Scout mission concept will be picked for 2007, with only one more every four years.

However, it's already clear that NASA's extension of the competitive Discovery concept to Mars exploration is likely to produce missions as fruitful for that purpose as the Discovery missions have already proven to be for exploring the rest of the inner Solar System - and it seems increasingly likely that the same competitive, flexible concept will soon be applied to the selection of the more difficult and expensive missions to explore the giant planets and the outer Solar System.

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LPSC 2001: A Martian Odyssey
Cameron Park - May 1, 2001
The 32nd Annual Lunar and Planetary Sciences Conference held in Houston during mid-March was a major scientific powwow that brought together scientists from all over world. In this special report, Bruce Moomaw takes SpaceDaily readers through the key papers presented and possible future directions for planetary science in the early 21st century.

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