On May 21, 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. A Dutch-made radio receiver aboard Queqiao will listen in the quiet lunar environment to the cosmos at low frequencies that carry clues to the time a few hundred million years after the big bang, when clouds of hydrogen gas were spawning the universe's first stars. The mission is viewed as 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 a test of cooperation with China, something their U.S. counterparts at NASA are barred from doing.

The Netherlands-China Low-Frequency Explorer (NCLE) project stems from a 2015 Dutch trade mission to China, during which the two countries agreed to collaborate on space missions. The Netherlands is strong in radio astronomy: Its Low-Frequency Array (LOFAR) stretches across much of northern Europe. China has an ambitious program of moon missions. Once funded, the team had just 1.5 years to build the instrument. "Half of the experiment is how you work together" Falcke says. Jinsong Ping of the National Astronomical Observatories of China in Beijing, who leads the Chinese team working on the NCLE, agrees: "It is really challenging both sides. … Different culture, habit, language, working manner." Once Queqiao arrives at L2, the NCLE will wait its turn until after the Chang'e 4 lander has achieved its main mission: exploring the South Pole-Aitken Basin, a huge far side depression. Then, around March 2019, the instrument will unspool three 2-meter-long carbon-fiber antennas, each at right angles to the others.