China’s Chang’e-3 lander and its Lunar-based Ultraviolet Telescope (LUT) are still operational, three and a half years after landing on the Moon. The LUT has been monitoring variable stars and stars like our own Sun, and also performing low-galactic-latitude sky surveys during the daytime periods over Mare Imbrium, the area in which Chang’e-3 landed.
Wang Jing at the National Astronomical Observatories under the Chinese Academy of Sciences (CAS) told gbtimes that the lander was still waking automatically after hibernating during a 14 Earth-day-long period of nighttime on the Moon.
Chang’e-3 is still in contact with ground stations in China during these periods of sunlight and transmitting data from LUT, which is the only instrument on the lander that is still operational.
The lack of atmosphere makes the Moon a prime place for UV astronomy, which is not possible at low altitudes on Earth, and the LUT has yielded some interesting results.
“The most significant scientific result from the LUT telescope is the water content in the lunar exosphere,” Wang says.
The lunar exosphere refers to the almost negligible amount of molecules above the Moon’s surface. If present in the Moon’s silicate rocks, OH and H2O molecules could be released due to micro-meteor impacts and the effects of the solar wind.
The presence of substantial quantities of water on the Moon would be a big boost for plans to establish a lunar habitat, as transporting water from Earth for astronauts would be very expensive. It would also serve as a potential source of oxygen and propellant.
However in situ measurements carried out by LUT revealed the concentration of OH/H2O molecules to be about two orders of magnitude lower than the values reported by previous missions, with the results reported in a paper by Wang and others.
Durable extraterrestrial first
While the Apollo 16 mission astronauts had a manual UV telescope, LUT is the first automated and remote operated telescope placed on an extraterrestrial body. It has also been taking advantages of the unique conditions during lunar eclipses.
China has its own Planetary Data System, maintained by the National Astronomical Observatories of China, which allows people across the world to access and download data and stunning images from its lunar exploration missions.
Wang was speaking at an event at the Global Space Exploration Conference (GLEX 2017) which opens formally on Tuesday. Steve Durst, director of the International Lunar Observatory Association (ILOA) which has Chinese partners, stated during a presentation at the same event that the power source for the Chang’e-3 lander could last for 30 years.
The lander, which was expected to operate for a year, is powered by a Radioisotope Thermoelectric Generator (RTG) and solar panels. Durst hopes that the mission will receive the necessary support on Earth to continue well into the future. Chang'e-3 was launched in December 2013, and has returned valuable scientific data from the Moon, adding to our understanding of our celestial neighbour. Chang’e-3 was due to awaken for its 44th lunar day on June 4.
The mission, which included the Yutu rover, also made China only the third country to soft-land on the Moon, following the United States and Soviet Union, and the first since the 1970s. China's next mission to the Moon will be the Chang'e-5 lunar sample return spacecraft, which is set to launch in November.
Above: The Yutu rover, imaged by the Chang'e-3 lander.