moonboun_redux_485.jpg: In what had to have been among the eeriest sensations ever felt by a human being, Apollo 12 astronaut Alan Bean took this photograph of astronaut Charles Conrad examining the Lunar Surveyor 3, a craft that landed on the moon nearly two years prior to Bean and Conrad's own arrival.

View Photo Gallery

Man's exploration of the moon has left behind over 20 tons of probes, rovers, rocket boosters and assorted other detritus scattered around the whole of the lunar surface. The moon has no atmosphere to burn up incoming objects, so once a spacecraft's orbit decays, it will eventually end up in a pile somewhere on the surface. Launch the slideshow for an in-depth history of every major lunar mission to leave something behind on the moon. And below, see the next four probes to eventually be added to the great lunar junkyard.

The next two years will see a blitz of activity around the moon, as spacecraft from China, Japan, India and the U.S. point cameras, spectrometers and other instruments at the lunar surface.

All four orbiters will scout sites for potential moon bases, hunting for water at the lunar poles and for pockets of mission-sustaining elements such as aluminum, oxygen and helium. According to Paul Spudis, a lunar expert at Johns Hopkins University's Applied Physics Laboratory and the lead scientist for the American imaging-radar experiment on India's satellite, each of the nations has serious ambitions to put their scientists on the moon. "Sending satellites is a logical first step," he says.

But there's more at stake than national pride-by broadening their space experience and displaying technological prowess, each country stands to lure lucrative contracts with companies looking to launch satellites. Although the overlapping objectives could allow scientists to cross-check data as it's radioed back by the orbiters, so far there's been little cooperation among the competing space agencies. "The missions were not planned on the basis of a coordinated strategy," Spudis says. To wit: India and the U.S. have agreed to share data, but Japan has not indicated that it will do the same, and China's space program is notoriously secretive. The race is on-may the best robot win:

China

• Craft: China National Space Administration's
  Chang'e 1 (named after a Chinese goddess who ingests a magic potion and flies to the moon)
• Mission: Circle the moon for a year and snap 3-D
  pictures of the sur-
  face, study its composition, and measure the thickness of the lunar soil
• Significance: As China's first moon flight, this mission will pave the way for robotic landers and human exploration
• Scheduled Launch: This spring


Japan

• Craft: Japan Aerospace
  Exploration Agency's
  SELenological and ENgineering Explorer (SELENE, the Greek goddess of the moon)
• Mission: Map the moon's surface and subsurface. Two subsatellites will help measure the moon's gravitational field and the remnant of its magnetic field
• Significance: Data produced by this orbiter will help scientists determine whether the moon formed from rocks surrounding an early Earth or from scattered Earth fragments
• Scheduled Launch: This summer


India

U.S.A.