Credit: NASA

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The space around Earth is a busy place. More than 500 active satellites are bustling about up there right now. Some are transmitting radio, television, and telephone signals; others are gathering information about the atmosphere and weather; still others are helping people navigate or are conducting space research.

Soon the Moon's orbit will be busy too. China, Japan, India, Russia, and the U.S. either have sent or plan to send satellites there for a bird's-eye view of lunar features and resources.

Partly, this is because it's nearby. We can see it better than we can see anything else in space. And it's reachable, even by countries whose space programs are in their infancy. It represents a grand first step for them. Indeed, two of those nations are already there: Japan and China are orbiting the Moon right now.

The Cadillac of missions

Japan's Kaguya spacecraft reached the Moon in October 2007. Its mission is to make detailed maps of the lunar surface, to search for water (a key resource for future human landings) frozen in deep craters, and to study the Moon's gravitational field.

"Kaguya is the Cadillac of missions right now," says lunar scientist Barbara Cohen of NASA's Marshall Space Flight Centre in Huntsville, Alabama. "It is huge, consisting of three separate satellites, and has excellent instruments. It will do a lot of particles and fields work that no other currently planned orbiter will do. Plus it will be able to train all its instruments toward the same spot on the Moon simultaneously."

Kaguya's main satellite carries 13 science instruments, including a HDTV (high-definition TV) camera, which is sending back incredible images of lunar landscapes stretching into the distance like an open road and Earth rising over the lunar horizon.

Barely a month after Japan reached the Moon, China followed suit. China's Chang'e-1 spacecraft entered lunar orbit on 5 November 2007. During its one-year mission, it will map the Moon by taking three-dimensional images of the entire lunar surface. This satellite will send back the first detailed pictures of some areas near the poles where water ice is most likely to be found.

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