The Chang’e-4 mission has been exploring the far side of the Moon since its historic landing back in January, providing us with some intriguing and never-before-seen observations of the lunar surface. Its rover, Yutu-2 (or Jade Rabbit), has also been pretty busy and over the summer it found something truly extraordinary: a gel-like substance with a different coloration from the surrounding soil.

The discovery happened on July 28, but it was only announced at the end of last month. No explanations have been officially given for the substance but researchers have shared new photos and insights of the area over on the rover's driving diary as well as in an official post from the Chinese National Space Agency itself, marking the rover and lander entering their 10th month of operations.

Unfortunately, there is little to glean from the pictures, but even collecting enough scientific data was a challenge for Yutu-2. The crater the substance had been spotted in was deemed too deep for the rover to get out of again. To use its Visible and Near-Infrared Spectrometer (VNIS), it had to drive right up to the edge.

"According to the coordinates given by the scientists, if the field of view of the infrared spectrometer is to cover the material, the front wheel of the rabbit must be suspended into the pit," researchers said. Luckily, with some skilled driving, they managed to negotiate the rover into a suitable position and it scanned the crater using the VNIS. This light reflected off the material and was used to work out its chemical composition.

The team then studied the data during Yutu-2's scheduled and very necessary midday "nap". Given the absence of atmosphere, things can get hot on the surface of the Moon (about 100°C/212°F) so the rover and lander shut down to avoid serious damage from overheating.

Researchers were disappointed to find out that the initial scans of the area from the lunar morning were affected by the many shadows in the crater, so they continued to study the unknown substance into the lunar afternoon, several more days. According to Space.com a "satisfactory detection" was made but the results have not been released yet. It was then put back into hibernation to sleep for the 14-day lunar night.

The two robotic inhabitants of the far side of the Moon woke up yesterday on schedule as the 10th lunar day of their mission dawns (a lunar day is roughly a month).

Researchers also used this project to analyze the bottom of the crater where the “gel” was discovered, as well as the spatter pattern from the meteorite that formed the crater. Some experts have speculated that the substance might have been formed in the impact and might be related to impact glass formed during a collision with a space rock. 

[H/T: Space.com]