Asia's race to the moon. Japan claims its project is the biggest since the Apollo missions put the first humans on the moon. China, hoping to pave the way for its own manned missions, says its probes will study the lunar surface to help plan a landing.
But the big question right now is not about science - it's who will get there first.
With Asia's biggest powers set to launch their first moon missions, possibly as early as next month, the countdown is on in the hottest space race since the Cold War.
Japan's space agency said last week its SELENE lunar satellite is on track for a Sept. 13 launch, following years of delay as engineers struggled to fix a slew of mechanical problems. China, meanwhile, was rumored to be planning a September launch for its Chang'e 1 probe, but is being coy as to the exact date.
Both sides say all systems are go.
The Chinese satellite and its Changzheng 3 rocket carrier have passed all tests, and construction of the launch site is finished, according to the National Space Administration's Web site. Last month, China's minister of defense technology told CCTV that all was ready for a launch "by the end of the year."
Officials have tried to play down the importance of beating each other off the pad, but their regional rivalry is never far below the surface.
But the planned lunar missions by China and Japan are among the most ambitious space programs yet.
Japanese space officials have said their 32 billion yen (US$276 million; EUR 203 million) SELENE project is the largest lunar mission since the U.S. Apollo program in terms of overall scope and ambition, outpacing the former Soviet Union's Luna program and NASA's Clementine and Lunar Prospector projects.
Japan is considering a manned mission by 2025.