Space Shuttle Endeavour comes at the end of era in NASA's history...What's next?

On the eve of Sunday's launch of space shuttle Endeavour, NASA Administrator Charles Bolden said he supports President Obama's goal of making the space industry a commercial venture, but is concerned about potential job losses at the agency.

Under Obama's proposed 2011 budget, NASA would take a back seat to private ventures. It would receive $6 billion over five years to invest in space technology research and develop private space taxis. This would replace NASA's traditional role of building its own spacecraft.

"We are departing from the model of the past, in which the government funded all of human space activities," Bolden told reporters.

"This represents the entrance of the entrepreneurial mindset into a field that is poised for rapid growth and new jobs. And NASA will be driving competition, opening new markets and access to space, and catalyzing the potential of American industry," he added. "This is a good investment for America."

The proposed budget -- which aims to tighten the nation's purse strings in certain areas while increasing money used to create jobs -- would cancel NASA's Constellation program, which had sought to send astronauts back to the moon by 2020.

Bolden conceded that many NASA jobs will be lost if Obama's budget passes, and said he was responsible for not preparing NASA employees for the changes that might occur.

"The reason why the NASA work force is not better prepared was because I didn't listen to people ... who talked about how we should roll these things out," Bolden said. "I thought I knew better, to be quite honest. So we rolled out the budget, we rolled out everything in the manner we did and it was screwed up."

"I learned a very hard lesson," he said.

Bolden said he hopes to recoup about 1,000 jobs by persuading Congress to keep some or all of the Constellation's Ares program, and that he was involved in talks on Capitol Hill. "Those are the sorts of negotiations I have to do," he added.

NASA already has begun planning and designing the hardware, propulsion systems and related technologies for the Ares V cargo launch vehicle -- meant to be the "heavy lifter" of America's next-generation space fleet, the agency has said. It would be used to launch equipment for use on space missions, and will have a heavier lift capacity than the Ares I booster.

Constellation was to follow NASA's space shuttle program, which, after about 30 years of taking astronauts to space, is scheduled to end later this year, following five more flights.

Critics say it is wasteful to abandon Constellation after $9 billion in federal money already has been spent on technology specifically designed for its missions.

The Endeavour is set to launch at 4:39 a.m. Sunday for its trip to the International Space Station. NASA said preparations remain on schedule, and the weather forecast is favorable.

Commander George Zamka will lead the mission, which is designated STS-130. Terry Virts will be the pilot, and mission specialists Nicholas Patrick, Robert Behnken, Stephen Robinson and Kathryn Hire will be aboard, NASA said.

Virts will be making his first trip into space.

The crew will deliver to the space station a third connecting module, the Italian-built Tranquility node and the seven-windowed cupola, which will be used as a control room for robotics. Three space walks are planned.