On the verge of a second launch countdown, the astronaut who will lead NASA's return to space said Friday it's not important when she and her crew fly, but that "we do it right."

Discovery (search) is scheduled to blast off Tuesday after a two-week delay caused by a malfunctioning fuel gauge, a "very elusive problem" in commander Eileen Collins' (search) words.

"We hope that we're able to launch on Tuesday," she said. "But regardless of when we launch, the launch date to us isn't that important. What's important to this process and that we do it right."

Collins made the comments after arriving back at Kennedy Space Center (search) with her six crewmates, following a brief trip to Houston for launch refresher training. It was the astronauts' first public appearance since July 13, when NASA halted its first shuttle launch countdown since the 2003 Columbia catastrophe.

Standing at the shuttle runway under a broiling midday sun, NASA's first and only female spaceship commander noted that it was a great day for liftoff. "We're hoping that this weather holds through all of next week — or whatever day we launch," she told reporters just 24 hours before the start of the three-day countdown.

Tropical Storm Franklin, brewing out in the Atlantic, was expected to remain well offshore.

The space agency believes an electrical grounding problem may have caused one of four hydrogen fuel gauges in Discovery's giant external tank to malfunction last week. It's the same type of problem that spoiled a fueling test of Discovery three months earlier.

Normally, all four fuel gauges must be working before NASA will fly. Managers, however, are considering going with just three good gauges if the problem recurs Tuesday, which would require a last-minute exemption of a long-standing launch rule.

The fuel gauges are critical for ensuring that the shuttle's main engines don't shut down too soon or too late en route to orbit, both potentially disastrous situations.

For the past few days, workers have been zeroing in on suspect grounding in Discovery's aft fuselage and possible electromagnetic interference from shuttle equipment that could be exacerbating the problem. It's virtually impossible to recreate the environment in which last week's problem occurred, officials said, without loading Discovery's tank with fuel and turning on all the systems.

That's why NASA is proceeding with an actual launch countdown and forgoing another fueling test.

To better isolate the problem, NASA is rewiring two of the four fuel gauges.

"We have a lot of confidence in what they're doing," Collins said, "and we think they have a great plan that they're going forward with."

Collins didn't address whether she'd have concerns about launching if only three of the four fuel sensors were working. She spoke for less than three minutes and didn't take questions.

NASA has until the beginning of August to send Discovery to the international space station. Then that's it until September because of the need for a daylight launch to ensure good photography.

The space agency lacked clear pictures of the foam strike that crippled Columbia during liftoff in January 2003. The hole in the wing led to the spacecraft's destruction during re-entry and the deaths of all seven astronauts.