NASA unveiled a 13-year, $104 billion blueprint yesterday for sending humans back to the moon as early as 2018, using modified space shuttle rockets to loft an Apollolike capsule into space.

Space analysts said the design was decidedly retro, harking back more than three decades to the Cold War's moon race. But they said the new design was safer and more realistic than the current space shuttle, which is scheduled to be retired in 2010 after nearly 25 years of service and two disastrous shuttle losses.

"Think Apollo on steroids," National Aeronautics and Space Administration head Michael Griffin said during a news conference at the agency headquarters in Washington, D.C.

The new capsule, known as the Crew Exploration Vehicle, will be significantly larger than the cramped Apollo capsule, with seating for as many as six astronauts instead of three. Slated for its maiden launch in 2012, it initially would be used to resupply and transfer crews from the international space station after the shuttle is retired, NASA officials said.

Unlike the winged shuttles, which are mounted on the side of the rocket, the capsule would sit atop the rocket, away from falling debris and potential engine fires that destroyed the shuttles Columbia in 2003 and Challenger in 1986.

NASA officials estimated the new craft would be 10 times safer than the space shuttle. The agency estimates that a space shuttle will be lost about every 220 missions. The new vehicle will be designed to go more than 2,000 missions without a serious calamity.

In 2018, NASA would launch the first back-to-the-moon mission, with new lunar landers and other components that would allow for as many as four astronauts to stay on the surface for as long as seven days.

The Apollo missions, which cost $150 billion, focused primarily on landing astronauts on the moon for a day or two and then returning them safely to Earth. The blueprint unveiled yesterday is part of a broader initiative launched by President Bush 18 months ago, in which he called for returning humans to the moon as a steppingstone to a manned mission to Mars, perhaps as early as 2020.

The new exploration plan would allow four astronauts to stay on the moon for a week — twice as long as Apollo missions. The capsule also would haul considerably more cargo, much of which would be left on the moon for future crews. In time, lunar stays of up to six months would be possible.

The capsule would return to Earth by parachute either on land or water — land being preferable, most likely at Edwards Air Force Base in California. And the capsule would be reusable, flying as many as five to 10 times. Apollo capsules were limited to one flight each.

"Much of it looks the same [as Apollo]," Griffin said, but he added, "It's a significant advancement over Apollo."

Unlike the Apollo program, which relied on massive Saturn V rockets to loft both the capsule and the lunar lander, NASA plans to send up two rockets, one carrying the crew capsule and the other the lunar lander.

The rocket to lift the crew capsule into space would be a modified solid rocket booster used on the space shuttle, while the lunar lander would be carried into space by a rocket made from a modified shuttle engine and external fuel tank. Once in orbit, the two spacecraft would rendezvous before making the journey to the moon. The new lunar lander would be able to carry four astronauts to the moon's surface, compared with two on Apollo.

NASA officials said using Apollo concepts and shuttle technology with the latest advances in materials, propulsion and avionics would allow the agency to meet the president's goals more efficiently and less expensively.

However, some observers worried that huge federal spending to rebuild New Orleans, which could cost more than $200 billion, could undermine funding for any major space initiatives.

But Griffin said the nation could afford the cost despite the hurricane-related expenses because he would not seek any new money for the agency's annual $16 billion budget. Instead, spending within NASA's human-spaceflight program would be redirected to pay for the endeavor, he said. About $4 billion to $5 billion a year is now allocated for manned spaceflight. Not "one thin dime" will be taken away from science projects, he said.

"There will be a lot more hurricanes and a lot more other natural disasters to befall the United States," Griffin said. "We must deal with our short-term problems while not sacrificing our long-term investments in our future."

House Majority Leader Tom DeLay, R-Texas, said the nation can fight the war on terrorism and deal with a disaster like Katrina while developing space technology for the future. "It is 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," DeLay said.