NASA released its master plan for returning humans to the moon by 2018 and eventually sending them to Mars, choosing rocketry from the space shuttle era and drawing inspiration from the Apollo program that first put humans on the lunar surface 36 years ago.

NASA Administrator Michael D. Griffin said the plan would cost $104 billion over the next 13 years, with increases for inflation, but would not require extra money beyond NASA's normal budgets.

The plan envisions the development of two new rockets, one of them almost as tall as and heavier than the Saturn V that launched the Apollo astronauts, and of a new spacecraft that can put four people on the moon for as many as six months before bringing them back to Earth in a parachute landing.

And though the rocket technology is "shuttle-derived," the new plan abandons the concept of a winged, reusable spacecraft that can fly back to Earth and land at an airfield. Griffin said the new "crew exploration vehicle" could be reused perhaps 10 times, but most of the new program's apparatus, as Apollo's before it, would be jettisoned in space or burned up in Earth's atmosphere.

Griffin also acknowledged that there will be a two-year period between the last space shuttle flight in 2010 and the first flight of the exploration vehicle, expected in 2012, during which the United States will have no ability to put humans in space.

This gap has been a space policy sticking point for more than a year between the Bush administration and Congress. Sen. Kay Bailey Hutchison (R-Tex.), chairman of the Commerce subcommittee on science and space and an outspoken advocate of closing the gap, issued an enigmatic statement saying, "I will do everything possible to keep the shuttle and crew exploration vehicle programs on course."

-- Guy Gugliotta

This NASA illustration shows recommendations for next-generation spacecraft. Plans for space exploration are expected to cost $104 billion over 13 years.