NASA hasn't given up on the red planet yet. On 19 March, officials gave a preview of Mars Odyssey, an orbiter set to launch on 7 April. They hope the mission, which is less ambitious than preceding efforts, will set the United States' troubled Mars Exploration Program back on track.
Since Daniel Goldin took over as NASA administrator in 1992, the agency has aimed to send a spacecraft to the Red Planet at each of the favorable launch opportunities that come about every 25 months. The 1996 Pathfinder mission was a highly touted success, as was the Mars Global Surveyor. But after those craft were launched, two other Mars probes failed en route, leading the space agency to conclude that it had cut too many corners in preparing for the missions. In the wake of the failures, NASA revised its long-term Mars Exploration Program last year, appointing a new Mars director and canceling plans to include surface rovers in this year's mission.
The Odyssey mission will focus on gathering data from orbit. The $297 million craft will take about 7 months to travel the 150 million kilometers from Cape Canaveral to Mars. Once stabilized in orbit, the spacecraft will circle Mars once every 2 hours while mapping the mineral composition of its surface. The data will allow scientists to piece together the geological history of the planet, and help them identify areas of Mars that may have harbored water--and the potential for biological activity--in the past. To determine whether there is water on Mars today, Odyssey will scan the planet for areas with high hydrogen concentrations and look for thermal spots, which might indicate the presence of hot springs. Then, beginning in 2003, the orbiter will serve as a communications relay between Earth and two rovers NASA plans to deploy to regions with promising water profiles.
"Mars Odyssey is a reaffirmation of the original 'faster, better, cheaper' commitment to go to Mars every 2 years," says Howard McCurdy, a space historian at American University in Washington, D.C. And getting another spacecraft to Mars 5 years after the last mission began will be an achievement. Looking back on the delay between the Viking missions in the mid-1970s and Pathfinder, he says, "for a guy who had to wait 20 years between Mars missions [this is] exciting."