A view of the lunar surface from the Apollo 8 spacecraft. NASA officials… (NASA )
WASHINGTON — Top NASA officials have picked a leading candidate for the agency's next major mission: construction of an outpost that would send astronauts farther from Earth than they've ever been.
Called the gateway spacecraft, it would hover in orbit on the far side of the moon, support a small crew and function as a staging area for future missions to the moon and Mars.
At 277,000 miles from Earth, the outpost would be far more remote than the current space station, which orbits a little more than 200 miles above Earth. The distance raises complex questions of how to protect astronauts from the radiation of deep space — and of how to rescue them if something goes wrong.
NASA Administrator Charles Bolden briefed the White House earlier this month on details of the proposal, but it was unclear whether the agency had the administration's support. Of critical importance is the cost, which would probably be billions, if not tens of billions, of dollars.
Documents obtained by the Orlando Sentinel show that NASA wants to build a small outpost — likely with parts left over from the $100-billion International Space Station — at what's known as the Earth-Moon Lagrange Point 2, a spot about 38,000 miles from the moon.
At that location, the combined gravities of the Earth and moon reach equilibrium, making it possible to "stick" an outpost there with minimal power required to keep it in place.
To get there, NASA would use the massive rocket and space capsule that it is developing as a successor to the retired space shuttle. A first flight of that rocket is planned for 2017, and construction of the outpost would begin two years later, according to NASA documents.
Potential missions include the study of nearby asteroids or robotic trips to the moon that would gather rocks and bring them back to the outpost. The outpost also would lay the groundwork for more-ambitious trips to Mars' moons and even Mars itself, about 140 million miles away on average.
Placing a "spacecraft at the Earth-Moon Lagrange point beyond the moon as a test area for human access to deep space is the best near-term option to develop required flight experience and mitigate risk," the NASA report concluded.
From NASA's perspective, the outpost would solve several problems.
It would give purpose to the Orion space capsule and the Space Launch System rocket, which are being developed at a cost of about $3 billion annually. It would involve NASA's international partners, as blueprints for the outpost suggest using a Russian-built module and components from Italy. And the outpost would represent a baby step toward NASA's larger goal: human footprints on Mars.
But how the idea — and cost — would play with President Obama, Congress and the public remains a major question. The price tag is never mentioned in the NASA report.
Spending is being slashed across the federal government in the name of deficit reduction; it's unlikely that NASA in coming years can get more than its current budget of $17.7 billion — if that.
One NASA supporter in Congress — Rep. Bill Posey (R-Fla.) — said he liked the idea of the outpost. But he said it would require strong White House backing to convince Congress to finance it.
NASA funding "always has been very precarious," Posey said. "And money is going to get tighter."
The White House did not respond to a request for comment, and a NASA statement was noncommittal about the outpost.
"There are many options — and many routes — being discussed on our way to the Red Planet," spokesman David Weaver said. "In addition to the moon and an asteroid, other options may be considered as we look for ways to buy down risk — and make it easier — to get to Mars."
A second major concern is astronaut safety. It would take days to get to the outpost — the farthest NASA has flown humans since the moon missions of 40 years ago. Another concern is how NASA would address the dangers of deep space, especially radiation.
The outpost would be more vulnerable to space radiation because it would be largely beyond the protective shield of Earth's magnetic field, said scientists with the National Space Biomedical Research Institute.
"It is significantly more difficult to shield and protect their [astronauts'] health" at that location, said Jeff Chancellor, a scientist with the institute.
These worries are not lost on NASA officials. The planning documents note that an outpost mission would require a "culture change" that included the "acceptance of risk significantly different" from the shuttle program, which lost crews in 1986 and 2003.
Still, the idea has the potential benefit of focusing NASA's human-spaceflight program, which has languished in recent years.