Two reports released this week savage NASA for attempting to do too much with too little on the missions, both of which failed late in 1999.

Thomas Young, who authored the report assessing NASAs overall Mars program, said its overall purpose remains valid.

"Weve concluded that Mars exploration is an important national goal that should continue, and we found nothing that would say otherwise," Young said.

Nonetheless, the reports have prompted immediate changes within the Mars program -- a harbinger of things to come.

On Tuesday, the American space agency announced it would send only an orbiting spacecraft to Mars in 2001, but delay dispatching a lander until 2003 at the earliest.

Further changes to the program, which was to culminate with the robotic return of samples of martian soil and rock to Earth by 2008, will not be announced until this summer, said Ed Weiler, NASAs associate administrator for space science.

Weiler said Tuesday his deputy, Earle Huckins III, would spearhead the effort to reconfigure NASAs architecture for its Mars exploration program.

The study will involve all NASA centers, including the Jet Propulsion Laboratory (JPL), as well as industrial partners and members of the science community. It will build on efforts already underway at JPL, which is responsible for NASAs Mars program

Unlike the old sample return-driven program, Weiler said the new, more robust campaign would focus on a longer-term approach to exploration, one that would carry NASA for at least a decade.

"The long-term vision for the Mars program plan will be a systematic search for the evidence of past and/or current life on Mars," Weiler said.

Key to that search will be the hunt for water on Mars, he added. The 2001 orbiter will kick that off by using its gamma-ray spectrometer to hunt for subsurface hydrogen on Mars.

Under the new program, mission teams will not be held to the strict caps and deadlines that a NASA investigation found likely doomed both the Climate Orbiter and Polar Lander.

"There will be no constraints on schedules -- up front or on launch vehicles. We will not tell them what to do. We will ask them to develop a plan that makes scientific sense, exploration sense," Weiler said. "We will then apply that against the budgets and the launch dates will fall where they fall."

The new program will focus on boosting NASAs reconnaissance, communications and navigational capabilities at Mars, Weiler said. Those goals would be met by a Mars Network project already under study at JPL. The network would consist of a swarm of microsatellites in orbit around Mars.

The tiny satellites, which could first venture to Mars in 2003, would constitute a so-called "Mars internet," boosting the communications link between Earth and Mars probes, allowing controllers to better target them as they approach the Red Planet. The microsatellites could also carry high-resolution cameras to build on the spotty understanding of Mars surface and what perils it may hold for landing spacecraft.

"We want to do that early in the program, not late," Weiler said.