NASA Watches Weather For Tuesday Rocket Test
The 327-foot-tall Ares I-X rocket sits perched atop Launch Pad 39B at NASA's Kennedy Space Center in Florida for an Oct. 27, 2009 test flight, but it's not the tallest structure there. On either side of the pad are 100-foot fiberglass lightning masts mounted atop 500-foot towers. The rotating service structure, or RSS, was retracted from the rocket at midday on Oct. 22.
Credit: NASA/Kim Shiflett

CAPE CANAVERAL, Fla. - The first test flight of NASA's new Ares I rocket is on track for a Tuesday launch, but the weather may not cooperate, officials said today.

The Ares I-X booster, an unmanned prototype of NASA's next-generation Ares I rocket planned to carry humans to orbit, is slated to lift off from Pad 39B at Kennedy Space Center here at 8 a.m. EDT (1200 GMT) on Oct. 27.

"I'm really happy to report that we aren't tracking any problems and the vehicle's in great shape," said Jeff Spaulding, launch test director, during a Sunday briefing. "We're looking very good for Tuesday's launch."

Mission managers' main concern at this point is the weather, they said - a gloomy 60 percent chance of cloudy skies is predicted.

"Our weather on Tuesday is going to be a little bit of a problem," said weather officer Kathy Winters.

Because Ares I-X the first test launch of a new rocket, and the purpose of the flight is to gather detailed visual and sensor data about how the booster performs, NASA requires pristine weather to launch. Winters said Ares I-X's weather requirements were more stringent than the conditions needed to launch the space shuttle.

A major difference is the rocket's risk for triggering something called "tribo electrification." The phenomenon occurs when the booster travels through clouds and stimulates static electricity that can cause interference in onboard instruments. The shuttle has been proven immune to this risk.

Ares I-X has a four-hour launch window on Tuesday - from 8 a.m. to noon EDT (1200 to 1600 GMT) - during which the rocket needs only about 10 minutes of clear skies to get off the ground. If launch is impossible Tuesday, NASA can try again during an identical four-hour window on Wednesday, when slightly better weather conditions are expected.

"I feel more optimistic about Wednesday than Tuesday," Winters said.

The full launch team spent Saturday running through a complete countdown rehearsal.

"That went really well yesterday afternoon," Spaulding said.

The $445 million trial flight will use a real first stage (albeit with only four solid-rocket segments, compared to the eventual five that are planned for Ares I), with a mock second stage and crew capsule on top to simulate the size and weight of the planned rocket. Ares I-X stands 327 feet (100 meters) high, making it the tallest rocket currently in service.

Tuesday's launch will mark a milestone for NASA's Constellation program, which includes Ares I and the Orion crew capsule planned to fly atop it. Yet the fate of Constellation is under review by President Obama, who is set to make a decision soon about the future of NASA and the goals he'd like America's human space program to pursue.

Some experts doubt that Ares I will make the cut, given that it was largely designed to serve as a space shuttle replacement to ferry humans to the International Space Station. With the space station set to be decommissioned in 2015, and Ares I not likely to ready until around 2017, some wonder whether building the rocket is worth the expense.

But whether or not plans for Ares I proceed, the upcoming test flight will still be useful, mission managers said.

"It's very significant data that is going to be very instructive to us since we haven?t done this in a long time," said Doug Cooke, associate administrator of NASA's Exploration Systems Mission Directorate, on Friday.

SPACE.com will provide full coverage of NASA's Ares I-X test flight with Staff Writer Clara Moskowitz in Cape Canaveral, Fla., and Managing Editor Tariq Malik in New York. Click here for full mission coverage.