With China's pioneering Chang'e-4 spacecraft settled in for a first lunar night on the far side of the Moon, the downtime gives us a chance to look at what plans China has for future lunar exploration.
We might not be waiting long for another complex and exciting Moon mission, as the Chang'e-5 lunar sample return—the first since the Soviet Luna 24 in 1976—is currently slated for liftoff at the end of 2019.
Consisting of a service module, lander, ascent vehicle and return capsule, the mission will attempt to land in Oceanus Procellarum on the near side of the Moon to drill down and collect up to 2 kilograms of samples and bring them to Earth following a lunar orbit rendezvous.
The mission and its goals have been long known and it marks the final stage of the three-step lunar exploration program set out in the early 2000s to orbit, land on and then return from the Moon.
China is however designing a new, fourth stage of missions, which will target the south pole, use new technologies and could involve cooperation with major space faring nations and agencies.
Towards a robotic lunar research base
The first open discussion of this new round of what could be 3 or 4 missions came at a Chang'e-4 mission news conference in Beijing last Monday.
Despite the numbering, the first of these missions could be Chang'e-7, which will, in the words of Wu Yanhua, vice administrator of the China National Space Administration (CNSA), attempt comprehensive exploration of the lunar South Pole, including analysis of topography, composition and the space environment.
Just as Chang'e-3 had a backup in Chang'e-4, a successful Chang'e-5 mission will mean Chang'e-6 would then be similarly repurposed for a more ambitious sample return mission, targeting either the lunar far side or south pole.
Chang'e-8 would then carry on the work of Chang'e-7 and additionally seek to test key technologies, such as 3D printing, with a view to establishing a what is being loosely described as a 'robotic research base' at the south pole, involving other countries—likely similar conceptually to ESA's 'Moon Village' concept.
Chang'e-4 has played its part in these plans by proving out new and improved precision landing technology that facilitated a safe descent and landing in challenging lunar terrain (make sure you check out the footage if you haven't already).
While this is all rather vague, further details of the new Chang'e mission concepts have been made available in conference papers from top lunar scientists. At a June conference in Macau, China last year, Zou Yongliao of the General Office of the Lunar and Deep Space Exploration under the Chinese Academy of Sciences gave a glimpse of the early plans for Chang'e-7. The mission is to consist of five spacecraft: an orbiter, relay satellite (whether this will be Qeqiao or a new spacecraft is not stated), lander, rover and 'fly-by robot.' The rover would analyze volatiles and the fly-by robot would be equipped with a water molecule and hydrogen isotope analyzer for in-situ detection of water ice in permanently shadowed areas.
Another paper, presented at LPSC 2018 (PDF) by Zou and others, also states lunar in-situ resource utilization and bio-scientific experiments as main scientific goals for the extended missions, along with an Earth-Moon Very Long Baseline Interferometry (VLBI) experiment involving the relay satellite. Chang'e-8, it says, could focus on in-situ rare-gas extraction and 3D-printing tests. Ecosystem experiments could also be carried out with a view to providing insight into systems to assist potential human lunar missions in the 2030s and even crewed lunar base concepts.
Who will be involved?
The press conference underlined that China is looking for partners for its lunar projects, and cited the coordination of images, data and landing information between teams involved in NASA's Lunar Reconnaissance Orbiter and China's Chang'e-4 mission.
CNSA Secretary-General Li Guoping also stated that China would be cooperating with Russia in its Luna 26 (Luna-Resurs-Orbiter) mission and on a Chinese lunar south pole landing, as well as research on lunar water ice and ultrasonic drilling. Beyond this, Chang'e-8 could involve input from ESA and others.
"We hope that Chang'e-8 will help test some technologies and do some exploring for the building of a joint lunar base shared by multiple countries," Wu Yanhua said, citing lunar 3D printing, which ESA is already researching.
When will all this happen?
Various timelines for the missions have been offered, none of which are official. One of the latest has Chang'e-7 launching in 2023 (as early as 2021 in others), followed perhaps a touch confusingly by Chang'e-6 in 2024, and Chang'e-8 in 2027. Another, presented (PDF) at the Sixty-first session of the Committee on the Peaceful Uses of Outer Space in June last year, has Chang'e-6 launching as soon as 2020, and Chang'e-7 and 8 in 2023 and 2026 respectively.
There are a few caveats to all of this. Chang'e-5 was intended to launch in late 2017, but the second Long March 5 rocket suffered a first stage engine issue and plummeted into the sea. It has not flown since but is expected to lift off from the coastal Wenchang launch center in Q2 this year.
That will be a crucial launch for China for its major exploration and human spaceflight ambitions. Only after a successful return-to-flight can the next Long March 5 send Chang'e-5 on the way to the Moon late this year. The same launcher is required to launch the country's first independent shot at Mars (orbiter and rover), in summer 2020. The Chinese Space Station project also waits on this, as the variant for lofting the 20-metric-ton space station to low Earth orbit, the Long March 5B, won't have its maiden flight until the Long March 5 is flying again.
In the longer term, it should also be noted that while China's space activities have enjoyed strong political and economic support since the late 1970s, a comprehensive and growing space program may still come under various pressures going forward, as with any program around the world.