"Its one of many options they are looking at," said David Paige, who was principal investigator on the main instrument package aboard the ill-fated Polar Lander.
The proposed near-duplicate spacecraft would arrive at Mars during the martian spring of 2003, targeting the same southern polar region with virtually the same payload as did the Polar Lander. The Polar Lander vanished after plunging into Mars' atmosphere on December 3, 1999, at the start of what would have been a 90-day mission.
"If you lose an objective, do you go back again or do you go on to the next thing?" Paige said. "Going back and recovering what you lose is always an option."
The Polar Landers failure followed immediately on the heels of the loss of the $125 million Mars Climate Orbiter in September 1999.
Together, the back-to-back losses have sent NASA back to the drawing board to rethink its Mars exploration strategy. The agency had intended to send paired lander-orbiter spacecraft to Mars every 26 months over the course of a decade.
The program would have culminated in the robotic return of samples of martian rock and soil to Earth in 2008. The samples would have been collected during missions launched in 2003 and 2005.
The 2003 lander, which originally included a small rocket to place samples into martian orbit for later pickup, has since been stripped of its sample return mandate.
Nor will it carry Athena, a giant 154-pound (70-kilogram) rover that was to have roamed as far as 0.6 miles (1 kilometer) from the lander to collect samples, said Mark Adler, Mars sample return chief engineer at NASAs Jet Propulsion Laboratory.
Instead, the 2003 lander may carry Marie Curie, a much smaller rover that is nearly identical to Sojourner, the six-wheeled robot that was the star of the 1997 Pathfinder mission. Marie Curie was originally slated to fly to Mars in 2001.
However, if NASA sends a lander to Mars in either 2001 or 2002, it may preclude a 2003 mission altogether because of cost, Adler said. He added that any plan for how to re-shuffle the Mars program has a "one-day half-life" at JPL.
"Things are in extreme flux right now," Adler said.
NASA aims to announce in late March the final changes it will make to the architecture and timing of its Mars campaign.
From a celestial standpoint, the 2002 shot would be less than ideal because of the distance between Earth and Mars at that stage. The journey to Mars would take the spacecraft nearly a full year to complete. However, it could be hurried on its way by flying by the planet Venus in order to get a gravity boost, Paige said.
Scientists are anxious to return to explore Mars south pole because the layered terrain that blankets the region. By digging into the sandwiched layers of dust, sand and possibly water ice there, a robotic spacecraft could peel back a portion of the planets climatic history, scientists have said.
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