First test flight of 'Ares I-X' next-generation space vehicle set for launch

AFP - A rocket that aims to replace the aging space shuttle fleet and carry astronauts into low-Earth orbit is poised for its first test flight Tuesday, amid deep uncertainty over the program's future.

Barring bad weather, countdown for the rocket that carries hopes of returning humans to the moon and for the first time to Mars will begin at 1:00 am (0500 GMT), with a four-hour launch window opening at 8:00 am (1200 GMT).

"The Ares I-X flight test vehicle is poised on Kennedy Space Center's launch pad 39B and is ready to fly," the US space agency said in a statement.

But while NASA scientists said they had "no issues" with the 327-foot (100-meter) prototype, the world's largest at present, the weather could still throw a spanner in the works.

The forecast for Tuesday shows only a 40 percent chance of favorable weather. NASA needs just 15 minutes of good weather to launch.

If weather concerns cloud the test launch, the next window will be from 1200 - 1600 GMT on Wednesday, when the forecast is for 60 percent "go."

If that falls through, the world will have to wait until next month to get its first look at the launch vehicle.

The flight, NASA said, will allow the agency to "test and prove hardware, models, facilities and ground operations associated with the Ares I launch vehicle," which is seen as a first step in US human space flight after the shuttle is retired.

NASA will gather data collected by more than 700 sensors placed throughout the rocket during the ascent of the integrated stack.

Only the first stage of Ares I-X -- a modified solid-fuel motor from the shuttle program -- will be tested, while the upper stage and capsule are mock ups.

Data obtained during the two-and-a-half-minute flight will help the US space agency determine whether the prototype is safe and stable in flight before the new generation of launch vehicles is used to take astronauts into orbit.

A team of experts has projected that will not happen before 2015, leaving a five-year gap after the shuttle is retired in 2010.

The test launch comes as the White House studies a report by a high-level commission set up by President Barack Obama to review plans for post-shuttle human space flight established by his predecessor, George W. Bush.

The panel chaired by Norman Augustine, a former executive at aerospace giant Lockheed Martin, concluded that the US human space flight program "appears to be on an unsustainable trajectory" and was seeking to achieve goals not matched by resources.

The Ares rocket has suffered major development problems, and its hefty price tag has fueled criticism of NASA, an agency notorious for its cost overruns.

The initial budget for the Constellation program, which includes Ares rockets, was set at 28 billion dollars, but has swollen to at least 44 billion.

Augustine Commission member Ed Crawley said last week that Ares I was "not the right ship" for post-shuttle space flight.

"The question is not can we build Ares I, but should we build Ares I," Crawley said.

The commission's review of the Constellation program proposed several alternatives, including sidestepping the rocket and going straight to the Ares V family of launch vehicles, which would take astronauts back to the moon and eventually on to Mars.