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China puts spacecraft into orbit around the Moon

Anatoly Zak, Spaceflight Correspondent
Jan 14, 2015, 1:39 UTC

Sen—Chinese space engineers graduated to a yet another level of sophistication in navigating the lunar neighbourhood this week after placing a spacecraft into orbit around our natural satellite.

The Chang’e 5-T1 experimental probe successfully completed three days of orbital manoeuvres on Tuesday, 13 January, entering its final orbit around the Moon just 200 km (125 miles) above its cratered surface, China’s official Xinhua news agency said.

The State Administration of Science, Technology and Industry for National Defense (SASTIND) confirmed that all engine firings on board the probe were successful and the spacecraft was in good condition and under control. 

Although China had previously mastered lunar orbiting and landing missions, Chang’e 5-T1 arrived at the Moon not from Earth, but from a region behind it, following an extremely complex trip through deep space.

The experimental spacecraft was first launched on 24 October and, after an eight-day mission, it made a loop around the Moon and returned into the Earth's vicinity. At that point, a heatshield-protected capsule, closely resembling a scaled down copy of the Russian Soyuz spacecraft separated from the mothership. The capsule then reentered the Earth's atmosphere and landed, demonstrating the capability to return soil samples from the Moon—a major goal of the Chinese lunar exploration program.

In the meantime, the box-shaped main spacecraft flew by the home planet and then revisited the lunar neighborhood. There, it manoeuvred itself into the so-called Lagrange L2 point, one of five areas within the Earth-Moon tandem where gravitational forces of two celestial bodies cancel each other out. As a result, the spacecraft can "hang" in some lagrangian points without use of much propellant.

The L2 point, where Chang'e arrived on 27 November, is considered especially important for the future lunar explorers, because of its perfect position for establishing communications between the Earth and practically anywhere on the far side of the Moon.

After a month-and-a-half-long spin around the L2 point 421,000 km (260,000 miles) away from the Earth, Chang'e 5-T1 left it on 4 January heading to the Moon 63,000 km (39,000 miles) away. 

At 03:00 Beijing Time on Sunday (19:00 UTC on Saturday), the Chang’e 5-T1 spacecraft first eased itself into a 200 by 5,300-km lunar orbit with three engine firings. This initial egg-shaped orbit required around eight hours to make a single revolution around the Moon. The probe then fired its engines again on Monday and Tuesday settling in a 200-km (125-mile) final orbit, where it needs just two hours and seven minutes for each full circle.

As a result, the Chang'e 5-T1 mission demonstrated not only the technologies for the immediate next step in the program—the return of soil samples—but also gave Chinese flight controllers an opportunity to practice intricate navigation techniques for future planetary missions.

According to the current schedule, the soil-scooping Chang'e-5 spacecraft will be launched around 2017.