In one proposal (the "Mars Mobile Lander"), a duplicate of the Mars Pathfinder will bounce to an airbag-shielded landing -- but the lander itself will consist only of landing and control systems, with no science instruments or radio gear.

Instead, it will unfold its petals to release a copy of the 130-kg "Athena" Mars rover that had already been scheduled for a 2003 landing as part of the now-cancelled mission to launch samples of Mars' surface into orbit around the planet for later pickup and return to Earth by a French/American spacecraft.

That far more complex mission has now been put off for some time to come, since its expenses (even before the 1998 failures) had quickly soared past the billion-dollar mark.

Not only will it take some time to finance and design the sample-return flight properly, but -- given the high expense of Mars sample-return missions, and the fact that they will each return only about a kilogram of samples from one location -- NASA now wants to make as certain as possible that the few landing sites selected are the most promising that can be found for possible microbial or chemical fossil evidence of ancient Martian organisms.

Athena was originally supposed to pick up a collection of tiny soil samples and drilled-out cores from selected Martian rocks, and return it to its mother lander for blastoff back into Martian orbit.

It will no longer have that function, but even without it Athena can still be an extremely useful tool for studying Mars' surface in unprecedented detail.

Athena, 11 times heavier than the tiny "Sojourner" rover on the first Pathfinder, is capable of operating entirely on its own -- communicating directly to Earth rather than through its lander, prowling for a kilometer or more across the Martian surface over a period of at least a month, and analyzing soil samples and rocks in great detail with a set of six different instruments. They would include:

1. A high-quality multispectral stereo camera;
2. A thermal-infrared spectrometer to make panoramic maps of surface minerals (especially water-deposited ones);
3. An alpha-proton-X ray spectrometer like the one on Sojourner, to analyze all the important elements in rock and soil samples;
4. A black-and-white microscopic camera to photograph soil grains and rock crystals as small as 0.03 millimeter;
5. A "Mossbauer" spectrometer that would bombard samples with gamma rays to make a chemical analysis of all iron minerals -- providing data on ancient Mars' water supply, and perhaps even identifying some iron mineral crystals that are produced on earth only by bacteria; and
6. A "Raman" spectrometer that would take spectra of laser light reflected off samples, not only identifying many minerals but also providing a sensitive check for traces of organic compounds in Mars rocks.