Obama has faced sharp criticism for proposing to abandon the Constellation moon program after nine billion dollars has been spent, and to allocate six billion dollars to support private companies in developing space rockets to carry astronauts to the International Space Station.

NASA's original Constellation program aimed at retiring the space shuttle fleet in late 2010 and replacing it with Orion spacecraft and Ares rockets by 2015. But an independent review by a White House committee found the program behind schedule and underfunded to accomplish its end-goal of returning astronauts to the moon by 2020.

"We've been there before," Obama said. "There's a lot more of space to explore."

The Obama administration estimates the new plan would create an estimated 2,500 jobs in the Cape Canaveral area.

To ease the transition for workers dislocated, Obama proposed a 40-million-dollar fund to help transform the regional economy around NASA's Florida facilities and prepare its workforce for new opportunities.

Obama's visit is the first time in 12 years a sitting U.S. president has visited the Florida spaceport.

The last Commander in Chief to visit the NASA spaceport was President Bill Clinton, who appeared to watch original Mercury astronaut John Glenn rocket into space aboard the shuttle Discovery at age 77.

Obama's proposal to cancel the Constellation program and call on commercial spacecraft builders to provide the spaceships to launch astronauts into space has drawn harsh criticism from lawmakers and the public alike.

Most recently, famed Apollo 11 astronaut Neil Armstrong -- the first person to walk on the moon -- and other lunar explorers spoke out against the plan in an e-mail statement sent to the media. Armstrong and fellow Apollo program astronauts Jim Lovell and Eugene Cernan called Obama's space vision "devastating" to the United States' spaceflight legacy.

"To be without carriage to low Earth orbit and with no human exploration capability to go beyond Earth orbit for an indeterminate time into the future, destines our nation to become one of second- or even third-rate stature," the former astronauts wrote.

Obama's new plan also has supporters.

"Space exploration involves more than human. The robotic exploration of space is doing very well, and is enhanced in the President's plans for NASA. The new human space flight program ... has the potential for ensuring U.S. leadership in space into the future," University of Michigan Professor Len Fisk told Xinhua in an email.

Buzz Aldrin, who landed on the moon with Armstrong during the 1969 Apollo 11 mission, also thought Mars is "the next frontier for humankind" and he hoped NASA "will embrace this new direction as much as I do."