China has launched a spacecraft that will act as a precursor for a robotic lunar sample return mission and perhaps also help prepare for subsequent manned exploration of the Moon.
Last Friday, a Long March-3C rocket lifted off from China's Xichang Satellite Launch Centre and set the spacecraft on a course for the Moon. The spacecraft’s trajectory sends it swinging around the Moon before heading back to Earth. Once back, its re-entry module will separate and descend through the atmosphere to touch down on the ground.
China embarked on lunar exploration with the launch in 2007 of Chang'e-1, a probe that imaged the Moon from orbit. Chang'e-2, another orbiter, followed three years later. Last December, the Chang'e-3 successfully put a lander and a small rover on the lunar surface; a malfunction, however, left the rover unable to move around soon afterwards. Chang'e-5, a robotic mission to bring back lunar soil and rock samples, is scheduled for 2017.
The current eight-day mission, which some analysts have called 'Chang'e-5-T1', is intended to test technology, particularly in re-entry, needed for Chang'e-5.
As it returns from the Moon, the Chang'e-5-T1 spacecraft will be travelling at about 11.2 km/second. Although China has sent astronauts into orbit around Earth and brought them safely back using its Shenzhou spacecraft, those spacecraft would have been moving less rapidly (close to 8 km/second). So the country's space scientists clearly want to prepare for re-entry at higher velocities.
Reports from the official Xinhua news agency indicate that a ‘skip re-entry’ manoeuvre will be attempted to slow the Chang'e-5-T1's re-entry module. The reentry module will be oriented such that it enters Earth's atmosphere, dissipates energy in the form of heat as it does so and then exits the atmosphere. According to a Chinese space agency spokesperson, there could be one or more ‘skips’ before final re-entry, with the capsule targeted to land in Inner Mongolia.
This re-entry module looks like a scaled down version of the one in Shenzhou that astronauts occupy during launch and for their return to the ground. That has added to speculation that China will, in due course, send its astronauts to the Moon.
In an article published earlier this year in the Go Taikonauts! electronic magazine, Chen Lan, an independent analyst who tracks the Chinese space programme, reviewed studies done by the country's space scientists and engineers on how manned lunar missions could be carried out.
He took the view that Chinese space planners were using robotic lunar missions as test-beds to reduce development cost and time for a manned effort.
However, a decision on manned lunar exploration may be made only after the sample return mission was completed, Mr. Chen Lan observed. “Considering its foreseeable huge cost and less practical returns, this should be a tough political decision. No one knows what will happen, even in China.”