Like the Chang'e-3 mission pictured here, CE5-T1 was a nighttime launch.

Like the Chang'e-3 mission pictured here, CE5-T1 was a nighttime launch.

Joel Raupe/Flickr (CC BY-NC-SA 2.0)

China's dash to moon a dress rehearsal for sample return

China raised the curtain today on the most ambitious act yet of its lunar exploration program. At just about 2 p.m. Eastern Daylight Time, the Chang’e-5 Test 1 (CE5-T1) spacecraft lifted off aboard a Long March rocket for an unmanned dash to the moon and back that aims to test technology for a sample return mission planned for 2017 and, a decade from now, possibly landing astronauts on the moon.

CE5-T1 marks China’s fourth lunar mission in the Chang’e series, named after a moon goddess in Chinese mythology. Chang’e-1, launched in 2007, spent 16 months in orbit snapping the nation’s first images of the lunar surface. Previous Chang’e probes were left in space. Guiding CE5-T1 back to Earth poses a new challenge; entering the atmosphere at a speed of 11.2 km/s is nearly 50% faster than the return speed of China’s Shenzhou spacecraft, which has carried orbiting astronauts safely back to Earth’s surface.

“Earthbound experiments can’t effectively simulate the complexity of the atmospheric environment,” Hao Xifan, deputy chief designer of the CE5-T1 and Chang’e-5 missions, told China’s S&T Daily newspaper shortly before the launch. He says CE5-T1 may be the sole spacecraft launched for engineering testing during China’s unmanned lunar exploration program.

According to Hao, a skip-reentry technology will be used to slow down CE5-T1. Comparing the technology to skipping a stone on a lake, he explained that the spacecraft will first dip into the atmosphere, then jump up, and finally make a gliding reentry toward touchdown. “The jump must be well controlled. If it’s too low, the probe may be burnt. If too high, it won’t be able to land in the targeted area.”

CE5-T1 is expected to arrive in lunar orbit on 26 October. It will orbit the dark side of the moon and then head home, with a parachute-assisted landing somewhere in middle Inner Mongolia 8 days after its departure.

“Although the upcoming mission is very risky, I have full confidence [in our success],” Liu Jizhong, deputy commander of China’s lunar exploration program, told S&T Daily.

Joining CE5-T1 atop the Long March 3C rocket today are two small probes from Europe. One is a radio beacon known as 4M. Developed by LuxSpace in Luxembourg, 4M will start transmitting radio signals back to Earth for amateur space enthusiasts soon after the liftoff. The other microsatellite is PS86X1 from the virtual organization Pocket Spacecraft. They will bid farewell to CE5-T1 on the way to the moon and conduct separate lunar flyby experiments.

CE5-T1 is a steppingstone to Chang’e-5, China’s last planned uncrewed mission to the moon. Among many other tasks, Chang’e-5 is slated to collect about 2 kilograms of lunar soil and return to Earth.