One of the most intriguing parts of the Mars rover Curiosity's landing is the lack of control that the scientists and engineers have in the final moments of the mission. Because it takes 14 minutes for signals to be transmitted from Curiosity to Earth, all they can do is watch, wait and hope for success.

Scott Hubbard, who is the former director ofNASA'sAmes Research Center and has contributed greatly to the Mars rover program, said: "Everybody is on edge. There's a lot of confidence there, but the truth is Mars is still mostly an unknown. It's a tense confidence. The software is loaded, they're committed, and now they just have to wait and see."

Hubbard says that the famous seven minutes of terror -- the length of time it will take the rover to make its descent to the surface -- are what will determine the success or failure of the mission. "It really comes down to seven preprogrammed minutes. I've had that type of experience before, and what I remember feeling is, 'Either it's going to be a good day, or it's going to be the end of my career.' "

PHOTOS: History of Mars exploration

If those seven minutes end badly, things might also end poorly for some scientists at Jet Propulsion Laboratory in La Cañada-Flintridge as well.

Hubbard says he believes that the stakes are especially high because the mission is funded by U.S. taxpayers.

"I spent seven months as the only NASA member on the Columbia investigation team. And from that experience, I learned that when you use tax dollars, there's a whole different level of expectation. Most people who climb Everest die, and it's 10 inches in the back of the newspaper for one day. But when Challenger happened, it was a major news event for months and months. When these things don't work, careers are bound to take a hit."

PHOTOS: Preparing for Martian landing

Over time, he says, NASA scientists have learned to approach their missions with a political eye.

"With Viking, there were really strong expectations that we would just mix dirt with water and find life right away," he said. When that didn't happen, he said, the results overshadowed some of the great scientific and engineering successes of the missions, and there were no more Mars missions until 1993. "Since then we've started really managing expectations, approaching our missions incrementally. I think that is part of the key to our success now."

With that, Hubbard headed to JPL to join his colleagues and await word from space.

INTERACTIVE: Curiosity, from liftoff to landing

ALSO:

Mars rover Q&A with Bill Nye the Science Guy

Photos: Preparing to land on Mars

Photos: History of Mars exploration