WASHINGTON -- NASA's 2001 Mars Odyssey is ready for a Saturday liftoff, as long as the Sun cooperates.

Solar activity is churning out higher than normal doses of protons -- high-energy particles that can wreak havoc with microelectronics on satellites, as well as rocket boosters. These energetic protons can zap equipment causing "single-event upsets" -- glitches in computers that can then send out faulty signals to hardware.

Scott Hubbard, Mars program director at NASA Headquarters, said the Mars Odyssey and its Delta 2 booster are ready for a Saturday liftoff.

"But we have to watch the space weather," Hubbard told SPACE.com between readiness reviews at Cape Canaveral, Florida where the 2001 Mars Odyssey will head Mars-ward.

"Space weather is always a launch constraint. It just happens that we're in a period of high solar activity. So we're keeping an eye on that," Hubbard said.

"There's a certain flux density that you don't want to exceed because it can result in a single-event upset in the Delta 2 computer," Hubbard said.

"While it's a standard operating procedure in the space business," you don't face it very often, Hubbard said.

NASA has a launch window that extends from April 7 to April 27.

There are two launch windows per day within a 20-day period. "But you always like to get off on that first one," Hubbard said. "You usually don't face this unless you have unusual activity, which we have right now," he said.

Hubbard said the Mars Odyssey mission is ready for its trek to Mars. "We've been through numerous reviews. Everything is on track for Saturday."

In essence, the Mars Odyssey is a robotic "return to flight" for NASA's Mars exploration effort. Back-to-back failures in late 1999 with the Mars Climate Orbiter and the Mars Polar Lander led to a major overhaul of the space agency's Mars plans.

The launch of the $297 million 2001 Mars Odyssey represents a milestone as the first launch in NASA's restructured Mars exploration program.

"I don't know anyone that is willing to say that we're 100-percent sure this is a slam-dunk success. But what I think we can say is that we have done everything possible to make Odyssey successful. And that's where we are," Hubbard said.