The US space agency NASA has chosen the Ames Research Center to manage upcoming robotic lunar missions that prelude astronauts' venture there by year 2018, officials said.

The institute, based in Mountain View, California, has planned at least four unmanned missions to the moon, mapping the entire lunar surface and scouting out water and safe landing sites for the astronauts.

These early missions will also help determine whether resources, such as oxygen, hydrogen and metals, are available for use in NASA's long-term lunar exploration objectives, the Ames Research Center said.

"The Robotic Lunar Exploration Program is a critical element of NASA's Vision for Space Exploration," said NASA Associate Administrator Scott Horowitz. "Data collected will help determine where we go, and what we find during our first human missions to the lunar surface."

Two of the unmanned missions are already being built, the officials said. At least two more ships, and perhaps a fifth, will also land on the moon, according to chief scientist Christopher McKay.

"An exploration science program with a sustained human presence on the moon gives us the opportunity to conduct fundamental science in lunar geology, history of the solar system, physics and the biological response to partial (earth) gravity," McKay said in a statement.

The first unmanned launch is scheduled for 2008. A spacecraft called the Lunar Reconnaissance Orbiter will circle the moon for a year or more to map the lunar surface and zoom in on the south pole, where in 1998 the first signs of water were discovered deep in the area's dark shadowed crater bottoms.

The orbiter is now being built at NASA's Goddard Space Flight Center, scientists said.

A follow-up mission will test a lander's ability to ground precisely in the moon's south polar region and start the search for areas flat enough to provide safe landing sites for humans.

That robot craft, now being developed by NASA's Marshall Space Flight Center, will also assess how much water might be available for the astronauts who land there.

The new series of robotic missions to the moon is aimed at making human exploration "sooner, safer and more capable," and one high priority is to come up with ways of landing precisely while avoiding hazards, Mckay said.

Scientists also want to know if the higher radiation and lower gravity levels on the moon would be safe for astronauts who stay up there for months at a time, rather than the few days spent by Apollo astronauts.

And they wonder if moon dust is hazardous. Although the astronauts are protected by space suits, the experience from the Apollo missions is that the dust is tracked back into the spacecraft and could be inhaled, McKay said.

The robotic ventures and the following manned lunar explorations are the first step of President George W. Bush's goal of sending humans to Mars, probing beneath its surface for signs of ancient life and perhaps one day even building colonies on the red planet.

Source: Xinhua