The new capsule, which would be designed to carry cargo or crew, would be three times larger than the Apollo capsule and able to carry up to six astronauts as opposed to three.

"Think Apollo on steroids," National Aeronautics and Space Administration chief Michael Griffin told reporters on Sept. 19, 2005.

Another difference between the new Crew Expedition Vehicle and the Apollo capsule is the CEV can operate without a crew in lunar orbit, enabling all astronauts to visit the surface as opposed to leaving one on board. And while Apollo was limited to landings along the moon's equator, the CEV will carry enough propellant to land anywhere on the moon, NASA said.

Initially, the CEV will ferry crews and supplies to the International Space Station after the space shuttles are retired in 2010.

Robotic missions are planned for 2008 through 2011 to study and map the lunar surface and look for resources, such as oxygen, hydrogen and metals that would be useful for long-term stays on the moon.

The first manned mission to the moon in the new spacecraft is planned for 2018.

Once a lunar base is built, crews could remain on the moon's surface for up to six months.

The capsule would be able to carry four astronauts to the moon and six astronauts on subsequent missions to Mars.

The craft would launch into space by a space shuttle-derived system consisting of a solid rocket booster and an "upper stage" powered by a shuttle main engine that can lift 25 metric tons, according to NASA. After missions, it would parachute-land on Earth either on land or in water.

NASA said the new spacecraft will be 10 times safer than the space shuttle because it will have an escape rocket perched atop the capsule to blast the crew away in case of a problem during launch, and its position on top of the rocket means the capsule will not be vulnerable to falling debris.

A heavy cargo launch vehicle sporting five space shuttle main engines and two five-segment shuttle solid-fuel rocket boosters will be able to carry at least 106 metric tons to low-Earth orbit, NASA said.

The $104 billion price tag spread over 13 years has generated debate in Congress with the ongoing war in Iraq and costly recovery of the Gulf Coast from Hurricane Katrina.

House Majority Leader Tom DeLay, R-Texas, said the nation can fight terrorism, deal with a disaster like Hurricane Katrina and work toward developing space technology. "It's expensive, but at the same time it's incredibly important because the return to the people of the United States and the world is also very important," he said, according to the Associated Press.

But others questioned the timing. "Given the funding shortfalls in the space shuttle program, there is simply no way to accelerate the development of the Crew Expedition Vehicle unless the NASA budget increases more than anticipated," said Chairman of the House Science Committee Sherwood Boehlert, R-N.Y., reported the Houston Chronicle.

The Apollo missions, which sent astronauts to the moon from 1969-72, cost around $150 billion in today's dollars, according to U.S. News & World Report estimates.

The blueprint NASA unveiled in September 2005 is based on President George W. Bush's 2004 "vision for space exploration" to safely return the space shuttle to flight, complete the International Space Station, return to the moon with sights on traveling to Mars and beyond.

In June 2005, NASA announced that it had chosen two teams from the aerospace industry to compete for the final contract to build the CEV -- Lockheed Martin Corp. and Northrup Grumman-Boeing.

Originally, the two teams were to have built separate vehicles in a head-to-head competition known as a "fly-off" that would have culminated in 2008, with one of the teams being awarded the final contract. The first manned mission was scheduled for 2014.

But once Griffin became NASA administrator in April 2005, he ordered an acceleration of the CEV program in an effort to shrink the gap between the phase-out of the shuttles in 2010 and the first manned missions in the new vehicle. Under Griffin's accelerated plan a final contractor will be chosen in 2006.

"We need to speed up development of the crew exploration vehicle and to complete the space station and retire the shuttle in an orderly manner," Griffin said on April 18, 2005. "Those are tall challenges, and I expect it will take the rest of my term to make sure that they are fully implemented."

-- Compiled from wire reports and other media sources