The other five instruments are firmly on the agenda. A mast on the rover's top carries a high-quality stereo camera to take multicolor and near-IR photos of the landscape to look for various minerals, and a thermal-infrared spectrometer to map the scene for minerals (especially those likely to have been deposited by ancient water).

And a small swiveling arm on Athena's front carries three more sensors that can be placed directly against a rock: an improved version of Pathfinder's "APX" spectrometer to measure all the important elements, a Mossbauer spectrometer to analyze iron compounds in detail (which can tell a lot about how wet an environment a rock was exposed to in its past), and a microscopic camera that will be used as a hand lens to view rock and soil grains and crystals in detail (and which has now been improved by changing it from black-and-white to color).

The arm also carries another gadget. Athena was originally supposed to carry a small but efficient drill to pick up tiny core samples of especially interesting rocks for storage in a basket and later return to the sample-return lander.

That's no longer necessary -- but the drill would also have allowed the onboard instruments to look at the freshly exposed ends of its rock cores; and that's still important, because all Mars' rocks are coated with a fine layer of dust, and they may have other kinds of weathered coatings on them as well that will interfere with the instruments analyses. So the arm also carries a "rock abrasion tool" that can scour the surface coating off rocks before the instruments analyze them.

Finally, there's the matter of picking the best landing site (or sites, if there are two rovers). Aviation Week magazine reported last week that the likely landing site has already been picked: the "Hematite Patch" in the Sinus Meridiani -- an area several hundred km wide where the IR spectrometer on Mars Global Surveyor surprised everyone by locating a vast bed of coarsely crystallized hematite which was very likely laid down on the bed of a huge lake on early Mars - or perhaps by volcanic hot springs, though less likely.

Obviously this could be a very promising site to look for fossils -- and it's smooth enough that the Pathfinder landing system should have absolutely no problem with it (in fact, it was the primary landing site for the cancelled 2001 Mars lander, which used a less rugged soft-landing system like the one on Mars Polar Lander).

However, Dr. Squyres told SpaceDaily, that Aviation Week was wrong -- the Hematite Patch is certainly one of the frontrunners, but since they now have until 2003 to pick out the best possible site, scientists probably won't start actually picking a site for a year or so, by which time the high resolution camera on MGS would have provided a lot more detailed coverage of the dangers and benefits of a large number of spots on Mars.

And that's where things now stand. Regardless of how the current controversy over whether to fly a second rover in 2003 ends up -- and regardless of the fact that the Athena mission carries two less instruments than had been planned -- it still promises to be not only a first-class PR spectacular, but a very useful mission scientifically after it lands on Jan. 20, 2004.

Meanwhile four additional missions are set to make their attempt at Mars over the next four years. These include the 2001 Mars Surveyor orbiter, Europe's Mars Express orbiter and its piggyback hard-lander Beagle 2, and finally Japan's "Nozomi" orbiter which is already weaving its slow and indirect way toward Mars to study the planet's upper atmosphere in 2003. The combination of these will, if they work, do an excellent job of getting Mars exploration back on its feet in time for the major decisions that must be made about its future course from 2005.

MARS 2003 - PART ONE - PART TWO - PART THREE - PART FOUR - PART FIVE

MARSDAILY.COM
How To Drill On Mars From The Comfort Of Your Desktop
Cameron Park - July 27, 2000 - Even if we succeed - through orbital or aerial radar sounding - in locating some spots on Mars where liquid water may be within a few dozen or a few hundred meters of the surface, we're left with the next stage of the problem: how do we drill down that far to reach it with unmanned landers and associated rovers at reasonable cost?