PASADENA, Calif PASADENA, Calif. Its the classic summer dilemma: fly or drive?
And its got millions of vacationers and NASA in a bind.
Ultimately, unusually high gas prices might force the issue when it comes to how to tote the kids to Aunt Ednas.
But for NASA, multiple factors weigh on the space agency's decision of what to send on the far-longer trip that it hopes to make to
Mars in 2003.The final word could come as early as next week on whether that year NASA will launch an orbiter to circle the planet or a complex rover to roam its surface or neither.
Until then, NASA continues to agonize over which robotic mission has the highest probability of success. Thats no mean feat, considering its 1999 stab at probing Mars resulted in the
failure of both an orbiter and a lander. "Mission success has to be number one," said Scott Hubbard, NASAs Mars Program Director, in a recent
interview with SPACE.com.But other factors creep into the equation as well: science value, cost and public engagement among them.
"We have two very viable options," said Jim Garvin, NASAs Mars program scientist. "When all other variables are considered time, risk and so forth how they engage the public might be as important as the science."
If thats the clincher, the lander option may have it in the bag.
The Mars 2003 Geology Rover would be just that: all rover and no lander.
More precisely, a Pathfinder-inspired
cushion of airbags would deliver a lander and rover to the surface, but the former would be dead on arrival, leaving the six-wheeled robot to explore on its own.
The cruise configuration for Pathfinder could be a template for the Mars 2003 mission.
Unlike Sojourner, the rover on 1997s Pathfinder, this far larger and self-contained robot would travel farther afield and make much more complex measurements of the Martian surface, including its mineralogy.
The rover would also return scads of up-close images of Mars of the kind that helped ring up more than 500 million hits to NASAs Pathfinder website in July 1997.
"Its my feeling its time to get back down on the surface and do science," said Ray Arvidson, the deputy principal investigator for the suite of instruments the rover would carry. "If we miss this opportunity, then the next opportunity is in 2005, we get down in 2006 and that means it will have been
~
a decade since Pathfinder. And prior to Pathfinder, it had been 21 years [since the twin Viking landers]. I dont think thats good for a program."
The big picture first?
Although perhaps less engaging, an orbiter might represent a safer, more prudent choice for NASA.
The agency already swims in global maps of the surface of Mars, but only a tiny percentage of it has been mapped at high resolutions, which makes it tough to pinpoint exactly what terrain future landed missions might encounter.
"We dont know much about Mars," Garvin said. "The next wrinkle might be to continue and attempt to embellish our ability to further collect high spatial-resolution imaging."
The Mars 2003 Surveyor Orbiter would carry a camera with a resolution in the range of 3.3 feet (1 meter), with the ability to double that during the early phase of the mission when the spacecraft would dip closer to the planets surface.
Although the images would still be taken from afar, recent events prove them to still be compelling.
Last month, NASA unveiled photographic evidence of the recent
flow of liquid water on or near the surface of Mars. The stunning images, gathered by the Global Surveyor satellite, left NASAs Mars program to wallow in a sea of positive coverage it hadnt enjoyed since Pathfinder."Clearly, orbiters are never going to be a yawn," said Louis Friedman, executive director of the Planetary Society, who favors sending a lander all the same.
But if NASA taps the Mars Surveyor Orbiter, it would be the fifth NASA satellite launched to Mars in 11 years. Two so far have failed, and third has yet to make it to the launch pad.
But assuming the 2001 NASA orbiter reaches its target, as well as Japans Nozomi and the European Space Agencys Mars Express, and the Global Surveyor stays its course, there could be an international flotilla of five satellites in orbit around the Red Planet by late 2003.
"If you add those up, you have to ask yourself what the crucial niche of another orbiter might be," Friedman said.
Whichever gets the tap, it will mark a retrenchment of NASAs previous plans to send an orbiter/lander pair to Mars every 26 months over the next decade.
In the wake of the failure last year of the latest such pair to be launched the Mars Polar Lander and Climate Orbiter NASA almost immediately scrapped plans for a landed mission in 2001, opting instead to send a lone orbiter.
The twin losses will still echo in the scaled-back plans for the 2003 shot, making it perhaps an even more painful choice between flying and driving.
"Wed love to have infinite resources and do both," Garvin said.
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