NASA's programs are undergoing a big shift under President Obama, who wants to cancel a Bush-era initiative designed to send Americans back to the moon.

The president's proposed federal budget includes a $6 billion boost in NASA funding over the next five years, bumping next year's budget to $19 billion.

Under the new guidance, space travel would be left for private companies while NASA focuses on science and technological advances.

"This is an extraordinary show of support in these tough budget times," NASA Administrator Charles Bolden said during a news conference Monday.

He highlighted the agency's new priorities:

Robotic exploration. Half of the budget increase would go towards unmanned exploration of the moon, Mars, and asteroids. Advances in satellites and cameras have made it possible to go further without endangering the lives of astronauts, Bolden noted. Such precursor missions would presumably be followed by manned ones.

International Space Station . Money would be aside to enhance the research capabilities of the station and use it as the "national lab it is intended to be," Bolden said. He noted that other nations have already expressed their willingness to help.

Research. The administration is prioritizing science education and research into astronaut health and technologies that could streamline missions.

Private partnerships. NASA is planning to spend billions to boost  commercial aerospace companies interested in private space travel. Bolden said the initiative could "drive the beginnings of a commercial crew industry with 5,000 jobs."

Congress will get to weigh in on how NASA operates as it review the president's budget. Bolden said he will work with lawmakers to ensure that the agency eases into the transition.

He emphasized that NASA funding is increasing, and that the new programs should supplement jobs lost by ending the Constellation program for lunar exploration.

"The program would not get us back to the moon within any reasonable time," he said, noting that it was running years behind schedule.

Not everyone is happy with nixing Constellation. Former NASA Administrator Michael Griffin told the Washington Post that commercial efforts aren't strong enough to take over NASA's role in space travel.

"It means that essentially the U.S. has decided that they're not going to be a significant player in human space flight for the foreseeable future," Griffin said.

-- Ambreen Ali, Congress.org