Even as Cutts addressed a conference on low-cost planetary exploration at Johns Hopkins University's Applied Physics Laboratory in Laurel, NASA officials were gathering in Pasadena to decide on what mission should be launched in 2003.
Liquid water is considered a prerequisite for life.
This aim is unlikely to be achieved with one mission that returns samples of the Martian surface to Earth, Cutts said. Cutts said it will also require global access to the planet, which has not been possible so far. The Mars Pathfinder mission, which sent a rover rolling around a small rocky area, had a limited range and stayed on the surface. A fleet of larger landers, lighter landers and so-called mini landers called scouts may be part of NASA's vision for Mars, Cutts said, along with vehicles that can dig beneath the surface. NASA hopes to get a sample back from Mars by 2010.