China’s moon mission is set to probe cosmic dark ages
Daniel Clery
On 21 May, China plans to launch a satellite with a vital but unglamorous mission. From a vantage point beyond the moon, Queqiao, as the satellite is called, will relay data from Chang’e 4, a lander and rover that is supposed to touch down on the lunar far side before the end of the year. But a Dutch-made radio receiver aboard Queqiao will attempt something more visionary. In the quiet lunar environment, it will listen to the cosmos at low frequencies that carry clues to the time a few hundred million years after the big bang, when clouds of neutral hydrogen were spawning the universe’s first stars. The mission is a proof of principle for other efforts to take radio astronomy above the atmosphere, which blocks key radio frequencies, and far from earthly interference. For Europe’s astronomers, it is also a test of cooperation with China, something their U.S. counterparts at NASA are barred from doing.