High tech instruments aboard the Odyssey will help the orbiter fulfill the mission's key objectives: finding evidence of water and geothermal activity on the Red Planet, mapping out the terrain, and measuring Martian radiation levels for future manned missions.

"We need to measure the radiation in the environment because we may be going with humans to Mars," said Scott Hubbard, NASA's Mars program director.

Saturday's launch marks NASA's first return to the Red Planet since the space agency restructured its Mars program in the wake of the failed Mars Orbiter and Mars Polar Lander missions in late 1999. The Orbiter was lost in space due to an international math misunderstanding in which some engineers used English units while others used the metric system. It's likely that a technical glitch in the systems controlling the Lander's engine caused that probe's crash-landing, which rendered it useless.

Low-funding and thin staffing were cited as major factors in those highly visible failures. On this mission, Hubbard said, NASA is doing many things differently, such as spending a comparatively lavish $297 million to fund the Odyssey project, and employing a team of risk reductioneers to identify potential problems with the craft.

According to George Pace, 2001 Mars Odyssey project manager at NASA's Jet Propulsion Laboratory in Pasadena, California, arduous testing of the hardware onboard the Odyssey has revealed no problems to date.

If all goes according to plan, the Odyssey should begin its two-and-a-half-year orbit around Mars sometime in October.

Water, water, anywhere?

Among the Odyssey's most important payload will be a gamma ray spectrometer that will scope out the Martian soil and examine the minerals in it. Finding hydrogen, Hubbard said, would provide further evidence that water -- a key ingredient to life -- is or was once available on the planet.

Odyssey, Hubbard said, is also equipped with a Thermal Emission Imaging System (THEMIS) that will look for hot spots, signs of geothermal activity that could point to the still-warm remains of dried-out hot springs on the planet's surface.

"If we find a hot spot, and if it was wet in the more recent past, that means that's where water has been. It means that Mars has had a lot of geothermal activity near the surface," explained Ben Clark, part of the team at Lockheed Martin's astronautics division that built the Odyssey for NASA. "That means volcanic activity may be going on yet today."

Scientists believe that warm and wet conditions on Mars would suggest the planet as a suitable place for life to thrive, either in the distant past or possibly the present.

Numerous studies have already provided ample evidence of the existence of water on Mars. However, a new study published in the journal Nature this week has disqualified at least one potential water site, the planet's vast northern flatlands. Previous research had suggested that an ancient Martian ocean had formed the area's geographical features, which resemble a shoreline.

But new evidence gleaned from images sent by NASA's Mars Global Surveyor, which is currently orbiting the Red Planet, suggests these features were likely the result of tectonic plate activity, said Paul Withers, coauthor of the Nature report.

Withers, a researcher at the University of Arizona's Lunar and Planetary Laboratory, is quick to note that his findings do not necessarily diminish the possibility of water on Mars.

"There are many other factors that we didn't look at that could still be candidates for water on Mars," Withers said.

The more sophisticated instruments aboard the Odyssey probe, Withers noted, will allow for more localized searches for signs of water.