Charles Whetsel is the chief engineer of the Mars Program.

Thirty missions to Mars have been mounted by the space agencies of the U.S., Japan, and the former Soviet Union. Of the U.S. missions, 10 out of 15, or two-thirds, have succeeded. Only one of 16 Soviet missions succeeded, and the lone Japanese spacecraft is currently delayed in arrival at Mars due to propulsion problems.

Charles Whetsel, now chief engineer of the Mars Exploration Program, points to the single most instructive lesson of his engineering career. He was two years into his first job out of college. On Aug. 21, 1993, as usual, he showed up for his 6 o'clock, Saturday night shift on the "systems" console for the Mars Observer mission. Only the spacecraft didn't. It disappeared as its propellant tanks were being pressurized in preparation for an engine firing that was to have placed the spacecraft into orbit around Mars. An investigation later determined that warm fuel had condensed in a cold part of the propellant lines too close to the liquid oxidizer, sparking an explosion.

"I'd never even thought about it, that I could come in tomorrow and everything I just invested the last two years in disappears in the blink of an eye," says Whetsel, now 34. "That was my big wake up. I was totally incredulous. Your world changes overnight.

"It affects you on a personal level and it affects everyone you work with. It's equivalent to finding out your company has gone bankrupt or something like that. But it's a little more personal than that. That whole process of losing it, then trying to get it back then working through the whole failure investigation trying to understand what went wrong. We were all working together with the external failure investigation board on that because we wanted to understand what happened."

As graduates of what Whetsel calls "the school of hard knocks," he and his colleagues, veterans of a failed mission and the detailed engineering detective work that followed, became even more valuable contributors to JPL's space exploration enterprise.

Former Soviet space engineer V.G. Perminov, who led design work for the U.S.S.R.'s Mars spacecraft program, wrote a publication called "The Difficult Road to Mars," in which he recounts that country's string of misadventures to the red planet. He points to a Russian proverb to help explain the value of lessons learned from failure: "One beaten person is worth two unbeaten ones."

Whetsel agrees. With a great deal of experience built up through his involvement in earlier missions, now oversees engineering concerns for all Mars missions. "Once you've lost one, it colors the way you look at things. You really push a little harder, you worry a little more."