China’s space ambitions: Robot on Mars, a human on the moon
China’s landing of its third probe on the moon is part of an increasingly ambitious space program that has a robot rover en route to Mars, is developing a reusable space plane and is planning to put humans back on the lunar surface.
China has proceeded more cautiously than the breakneck U.S.-Soviet space race of the 1960s, which was marked by fatalities. China’s crewed missions have gone ahead without incident. Some launches of robot vehicles have been delayed by technical problems but those appear to have been resolved.
While Chang’e 5 gathers moon rocks, Japan’s space agency just pulled off the even more challenging feat of obtaining samples from an asteroid, Ryugu. The Hayabusa2 mission is due to deliver those to Earth on Saturday.
It has joined the race to explore Mars, and its Tianwen-1 probe, launched in July carrying a robot rover to search for signs of water, is due to complete its 470-million kilometer (292-million mile) journey in February.
The agency announced in September its space plane had completed a successful test flight but has yet to release details or even a photo of the craft.
The Russian Luna sample return missions used a simpler direct ascent profile to return to earth, partly due to this the amount of sample they could return was vastly smaller than Chang'e 5. In addition Luna's ascent stage had a KRD-61 engine which could only be lit once and could not be throttled, so it must complete both the ascent back to lunar orbit as well as the injection back to earth in a single burn. This means the landing must take place at a precise location on the moon. If the craft missed its landing spot it may not be able to return to earth because orbital parameters may not allow a single burn of the engine to complete both ascent and ejection.From what I've read of the difference between the American, Russian, and Chinese missions was the US had astronauts retrieve samples. The Russian one was automated and with a direct from the moon to earth return vehicle but that could only be done from certain parts of the moon. The Chinese one was automated also but the sample is shot up to orbit where it will dock with the return vehicle to go back to earth. That could be done from any part of the moon.