China’s Chang’e-4 Probe Survives Its First Lunar Night

After the world’s first soft landing on the far side of the moon, the Chang’e-4 probe from China has survived its first lunar night. In the morning temperatures were minus 190 degrees centigrade, according to the national space agency.

Both the rover and the lander parts of the Chang’e-4 probe have awoken to sunlight after a long “slumber during the first incredibly cold night on the moon, the China National Space Administration (CNSA) stated. One lunar day is equivalent to 14 Earth days and one lunar night is also 14 Earth nights. The Chang’e-4 probe was put in dormant mode during the two-week lunar night because of a lack of solar power.

The Chang’e-4 landed on the far side of the moon on January 3, making it the world’s first to land on that side of moon’s uncharted territory which is never visible from our planet. This also marks the first time Chinese experts have received first-hand data concerning the temperatures on the surface of the moon in the midst of the lunar night.

Ar 8:39 pm on Wednesday the lander was awake, and the rover known as Yutu-2 (Jade Rabbit-2) was woken around 8:00 pm on Tuesday, the CNSA said. Due to the tidal locking effect, the moon’s rotation cycle is the same as its revolution cycle, so the same side of the moon is always facing Earth.

Zhang He,  from the China Academy of Space Technology (CAST) and the executive director of the Chang’e-4 probe mission explained that as per Chang’e-4's measurements, the shallow layer of the lunar soil's temperature on the far side of the moon is less than the info sent back by the US Apollo mission on the near side of the moon.

Zhang, who was quoted by the state-run Xinhua news agency added that it is probably a result of the difference in what the lunar soil is made of between the two sides of the moon, but further analysis is needed. There is an enormous difference in temperature between day and night on the moon. Before now, Chinese scientists did not have any data on exactly how cold it could get.

China deployed Chang’e-3 at the end of 2013, it was the country’s first craft to soft-land on the moon. The scientific instruments on this lander are still functional after more than 60 lunar nights throughout five years.

Measuring the temperature changes between lunar day and lunar night will enable scientists to better estimate the properties of the lunar soil, according to Zhang. The rover and the lander come equipped with a radioisotope heat source, which allowed the probe to stay warm during the 14-day lunar night.

The lander was also outfitted with an isotope thermoelectric cell and many temperature data collectors that can measure the temperatures on the surface of the moon when it is the lunar night.

Sun Zezhou, the head designer of the Chang’e-4 probe who is also from CAST said that for the first time used on a Chinese spacecraft, the isotope thermoelectric generation technology transforms heat into power aboard Chang’e-4. It is a prototype for future deep-space exploration.

NASA’s Curiosity rover also uses this power technology, which allows it to function even in lack of sunshine, or with sand and dust restrictions. This technology will be necessary to journey to the moon’s polar regions or even farther than Jupiter into deep space, where it’s impossible to use solar power as the primary source of energy, said Zezhou.

Chang’e 4 gets its name from the goddess of the moon in Chinese legends. It is the fourth lunar probe deployed by China since the country’s lunar program began in 2004.

Photo credit: CNSA

Jessica Zeitz