• NASA plans a return to the moon by 2018
• A lunar base will support future missions to Mars
• NASA crews will be able to stay for up to six months in the outpost
"A lunar outpost just three days away from earth will give us needed practice of 'living off the land' away from our home planet before making the longer trek to Mars." - NASA
Story in full ASTRONAUTS are to return to the moon after an absence of almost half a century, NASA announced yesterday as it unveiled plans for a network of lunar bases that would pave the way for journeys to Mars and beyond.
Astronauts would initially be expected to stay on the moon for week-long periods, developing technology and techniques needed for opening the space frontier, beginning with journeys to the Red Planet.
Building on the best of the Apollo mission technology, which last helped men walk on the lunar surface in 1972, as well as utilising more modern shuttle developments, NASA said it was creating a 21st-century exploration system that will be "affordable, reliable, versatile and safe".
But in the world of space science affordability is a relative concept, and the price tag for the project, coming in at a hefty $100 billion, has suffered fierce criticism on Capitol Hill, given US government commitments to the Iraq war and recovery from Hurricane Katrina.
The centrepiece of the mission will be a new space craft designed to carry four astronauts to and from the moon, support up to six crew members on future missions to Mars, and deliver crew and supplies to the International Space Station.
Astronauts will launch on a rocket made up of a single, solid-fuel booster, with a second stage powered by the new shuttle's main engine.
A crucial part of the proposed craft will be the Crew Exploration Vehicle (CEV). Shaped like an Apollo capsule, the CEV will be three times larger, allowing four astronauts to travel to the moon at the same time.
While the original Apollo was limited to landing on the moon's equator, the new lunar landing will carry enough fuel to land anywhere on the moon's surface, and will be driven by liquid methane, in preparation for a day when future missions can convert Martian atmospheric resources into methane fuel.
Once a lunar outpost is established, NASA said its crews could remain on the moon's surface for up to six months, and the spacecraft will be able to operate without a crew in lunar orbit, eliminating the need for one astronaut to stay behind while others operate on the surface.
In response to recent technology problems on the space shuttle that have cost the lives of astronauts, NASA said: "These launch systems will be ten times safer than the shuttle because of an escape rocket on top of the capsule that can quickly blast the crew away if launch problems develop.
"There's also little chance of damage from launch-vehicle debris, since the capsule sits on top of the rocket."
It added that in just five years, the new ship will begin to ferry crew and supplies to the International Space Station.
"Plans call for as many as six trips to the outpost a year," NASA said. "In the meantime, robotic missions will lay the groundwork for exploration."
NASA released a date of 2018 as the time when humans will again walk on the moon. After that date, NASA expects a minimum of two missions a year to quickly build momentum towards a permanent outpost. Crews will stay longer to learn to exploit the moon's resources, while landers make one-way trips to deliver cargo.
Planners are already looking at the lunar south pole as a possible outpost because of concentrations of hydrogen thought to be in the form of frozen water, and an abundance of sunlight to provide solar power.
NASA added: "These plans give us a huge head-start in getting to Mars. We will already have the heavy lift system needed to get there, as well as a versatile crew capsule and propulsion systems that can make use of Martian resources.
"A lunar outpost just three days away from earth will give us needed practice of 'living off the land' away from our home planet before making the longer trek to Mars."
However, the US president, George Bush, who first announced his vision for space exploration in January 2004, may still encounter problems is realising his grand dream.
Representative Bart Gordon, a Tennessee Democrat on the US House Science Committee, said: "This plan is coming out at a time when the nation is facing significant budgetary challenges.
"Getting agreement to move forward on it is going to be heavy lifting in the current environment, and it's clear than strong presidential leadership will be needed."