A Chinese lander and rover are still up and running more than 1,000 Earth days after they made a historic first-ever landing on the far side of the moon.
The Chang'e 4 lander carrying the Yutu 2 rover touched down in Von Kármán Crater on Jan. 2, 2019, and the robotic mission has been exploring the unique area of our celestial neighbor ever since.
Both spacecraft reached the 1,000-days-on-the-moon mark on Sept. 28. The Yutu 2 rover has covered a total of 2,754 feet (839.37 meters) of lunar ground and acquired 3,632.01 gigabytes of data during its driving, Chinese officials have said.
Together, the two spacecraft have returned stunning images and panoramas from the lunar far side, revealed secrets from below the surface, measured how much radiation astronauts would face, and have been spotted by NASA's Lunar Reconnaissance Orbiter.
Yutu 2 has set a new longevity record for a rover working on the surface of the moon, surpassing the previous record of 321 days set by the Soviet Union's robotic Lunokhod 1 rover. Yutu 2 is now headed toward a distant basaltic area, but it may take years to reach the new site.
Despite dealing with alternating deep cold and searing heat of lunar nights and days, intense solar radiation and abrasive lunar regolith, Chang'e 4, named after the Chinese goddess of the moon, and Yutu 2 ("Jade Rabbit 2"), the mythical pet rabbit of Chang'e, are still working well, as are their scientific instruments, according to the China Lunar Exploration Program.
The solar-powered spacecraft regularly shut down during the lunar night, each of which lasts about 14.5 Earth days. The pair began their 35th lunar day on Sep. 29.
The satellite that allows the Chang'e 4 mission to communicate with Earth is also healthy. The Queqiao (“Magpie Bridge”) relay satellite launched in 2018 to orbit around a point beyond the moon, from where it can see both the lunar far side and Earth at all times.
Queqiao is needed to bounce data and commands between the spacecraft on the moon and mission control because the lunar far side never faces Earth.
Some of the published results from Chang'e 4 data are still being discussed. A recent 'Matters arising' piece in the journal Nature Astronomy authored by Elena Pettinelli and others challenges interpretations of low-frequency ground-penetrating radar data made by J. Zhang et al. last year, contending that some signals presented as layers of rock are instead artifacts generated by the radar's system design and antenna configuration, in a similar manner as occurred with the same instrument on Chang'e 3.
Zhang at al. replied, confirming that there were electromagnetic disturbances, but the team had taken steps to identify and remove this noise from the data, allowing for insight into the layering beneath Von Kármán crater.
Chang'e 4 was originally designed as a backup to Chang'e 3 and would have provided a second shot at a lunar landing and rover mission if the first failed. Chang'e 4 was repurposed for a more ambitious mission after the successful 2013 landing of Chang'e 3.
The first Yutu rover lost its ability to drive after just two lunar days due to a short circuit. Yutu 2 was redesigned to prevent rocks damaging its circuitry and has proved much more durable.
China launched its first lunar sample return mission in late 2020. The Chang'e 5 mission successfully delivered 3.816 pounds (1.731 kilograms) of fresh lunar samples to Earth in December. The country will follow up by sending Chang'e 6 to collect samples from the far side of the moon in 2024.
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