PASADENA, Calif. (AP) _ Spurred by criticism over failed missions, NASA's Jet Propulsion Laboratory has chosen scientist Firouz Naderi to head a newly formed Mars program aimed at improving future robotic explorations.

Naderi was previously the manager of NASA's Origins Program, which specializes in searching for signs of life beyond the solar system.

``I don't think I've ever had as much fun in a job as when I worked Origins,'' he said. ``I hope I bring the same interest and enthusiasm to the Mars program.''

The new Mars program was created two weeks ago in response to a critical report on last December's failed $165 million Mars Polar Lander mission. The report blamed underfunding that led engineers to cut corners on testing and other safeguards. The lander failure came on the heels of another embarrassing gaffe: the September loss of the $125 million Mars Climate Orbiter when nobody realized navigation data was in English units rather than metrics.

Naderi's appointment, announced Friday by the NASA, is effective immediately. Since joining JPL in 1979, Naderi has also served as program manager for space science flight experiments and project manager for the NASA Scatterometer project.

Naderi, 54, said his first priority will be the 2001 mission to launch another Mars orbiter.

``Success breeds success,'' he said. ``I think that if we're successful in '01, then we'll get the public sentiment back, and I think that helps a lot.''