Leonard David's INSIDE OUTER SPACE

Yutu-2 rover as imaged by Chang’e-4 lander earlier in the farside mission.
Credit: CNSA/CLEP

China’s lunar rover Yutu-2 has begun taking its second snooze today, a midday nap, on the farside of the Moon.

According to China Central Television (CCTV), without a good thermal control ability, the rover is experiencing midday temperatures surpassing 100 degrees Celsius.

The rover will be awakened again on Friday.

Nighttime temperatures

The Yutu-2 and lander of the Chang’e-4 mission were awakened by sunlight on Jan. 29 and 30 respectively after a long “sleep” during the first extremely cold night on the Moon.

Image of Chang’e-4 lander taken by Yutu-2 rover early in the farside mission.
Credit: CNSA/CLEP

Nighttime temperatures on the Moon plummeted to minus 190 degrees Celsius, the first data China has obtained about temperature on the lunar surface during the 14-day long nighttime.

China’s Chang’e-4 lander/rover landed on January 3 within the Von Kármán crater  in the South Pole-Aitken Basin on the farside of the Moon.

Von Kármán crater as viewed by NASA’s Lunar Reconnaissance Orbiter Camera, or LROC,
Credit: NASA/GSFC/Arizona State University

 Scientific tasks

During the first lunar day (14 days in length), the lander and the rover photographed each other, and a camera installed on the top of the lander took 360-degree panoramic photos of the surrounding of the probe.

The Chang’e-4 mission carries four payloads developed by the Netherlands, Germany, Sweden and Saudi Arabia.

Scientific tasks of the farside exploration include low-frequency radio astronomical observation, surveying the terrain and landforms, detecting the mineral composition and shallow lunar surface structure, and measuring neutron radiation and neutral atoms.

Soviet Lunokhod rover
Credit: NASA/GSFC/Arizona State University

Washout

Yutu-2’s on again/off again surface treks sparked a comment from Ron Creel, Apollo Lunar Roving Vehicle Team Member.

“The ‘Lunar Nap’ that the Chinese vehicles are taking is most likely caused by ‘washout’ of visibility of lunar terrain for driving at times near lunar noon,” Creel told Inside Outer Space.

“This is what the Russians have shared with me that they also had to do the same driving pauses with their Lunokhods,” Creel advised. The former Soviet Union’s Lunokhod 1 rover was the first of two robotic lunar rovers that successfully landed on the Moon. It surveyed the Sea of Rains in 1970-1971. Lunokhod 2 wheeled about in Le Monnier crater in 1973.