An artist's concept of Mars Odyssey during orbit insertion engine firing. Photo: NASA TV/Spaceflight Now

"How sweet it is."

That was the message from NASA Administrator Dan Goldin at the late-night press conference to confirm the 2001 Mars Odyssey craft had successfully entered orbit around the Red Planet, a triumph for the space agency that had lost its two previous Mars probes.

An hour earlier, as the control room at the Jet Propulsion Laboratory erupted in applause, hugs and handshakes when Odyssey established contact with Earth following its make-or-break engine firing, Goldin was heard saying, "This feels better than a few years ago, doesn't it?"

NASA was counting on Odyssey to succeed after back-to-back failures of its Mars Climate Orbiter and Mars Polar Lander spacecraft in 1999. The embarrassing blunders have prompted NASA and industry alike to focus on details to ensure success, and the space agency has realized its shoe-string budget for Mars exploration just wasn't adequate.

The Mars Climate Orbiter crashed into the planet after a metric conversion error caused controllers to miscalculate its trajectory properly, and Mars Polar Lander likely impacted the surface due to a design flaw with its descent system that went undetected.

So NASA's Mars effort underwent a major facelift with new senior leaders, a slower approach to the long-term vision of exploration and more money to ensure the spacecraft are built and flown properly.

Odyssey was subjected to one of the most rigorous pre-flight testing and review processes. Its $297 million mission aims to map the chemical composition of Mars and find the most interesting places on the planet where future probes can be sent to search for water and the possible evidence of past life.

"It's a little scary when you think about it: 250 million miles, everything's done robotically by pre-ordained computer sequences," Ed Weiler, associate administrator for space science, said before Odyssey blasted off in April atop a Boeing Delta 2 rocket from Cape Canaveral, Florida.

"On the other hand, we've done every single thing we know how to do on this mission. Money was not an issue. We spent as much money as we needed to. We had independent reviews and then we had reviewers check the reviews. We had people checking units, metric to (English), and then we had people checking the checkers. What else we can do, I just don't know. This thing's got to work."

NASA's success rate at Mars is about 60 percent. When you factor in the Russian missions sent to the Red Planet, the overall success rate is less than 30 percent.

"We always want successes, but if there's one message I try to get through to the American people -- and I say it every single press conference -- this isn't a trip to grandma's house," Weiler said. "We're going to another planet, which is a long, long journey."

With Tuesday night's 20-minute engine firing to enter a 19-hour long, highly-elliptical orbit around Mars completed, the challenging task of refining the orbit to the desired science altitude begins.

"Orbit insertion is our single most critical event during the mission, and we are glad it's behind us," said David A. Spencer, Odyssey's mission manager at JPL. "But we cannot rest on our laurels. The aerobraking phase will be a demanding, around-the-clock operation, and it requires the flight team to react as the atmosphere of Mars changes."

The orbit insertion maneuver saw the spacecraft's main engine fire to slow Odyssey's speed, allowing it to be captured by Mars' gravity into the egg-shaped orbit. Starting on Friday and continuing for more than 70 days, the craft will repeatedly dip into the upper atmosphere, using the atmospheric drag to circularize the orbit to 250 miles above the planet in a process called aerobraking.

"Our job is not over until we return a rich harvest of science data. We still have ahead of us an aerobraking campaign and we have to prepare the spacecraft to perform its orbital tour mission. And only then, after we complete that, will I feel that we have a success, although we are very happy tonight," said Matt Landano, the Odyssey project manager.

NASA says flight controllers will work through the night to analyze the information they are receiving from Odyssey, thus determining the precise orbit geometry. A news conference is scheduled for 1700 GMT (1 p.m. EDT; 10 a.m. PDT) Wednesday to provide more details.