The first samples of moon rocks to come back to Earth since 1976 have landed. On 16 December, the Chinese Chang’e 5 spacecraft brought back about two kilograms of lunar material after a quick mission lasting only about two days on the moon’s surface.
Chang’e 5 landed on the moon on 1 December and on 3 December. The spacecraft’s time on the moon was short because it was solar powered and not built to survive the frigid lunar nights, which can reach temperatures as low as -173°C. Lunar days last about 14 Earth days.
“As a lunar scientist, it’s just really inspiring and makes me take a sigh of relief that we’re back on the surface of the moon collecting samples for the first time in almost 50 years,” says Jessica Barnes at the University of Arizona. The last mission to return samples from the moon was the Soviet Luna 24 probe in 1976.
After two samples were collected, one from the surface and one from about two metres underground, they were loaded into the ascent stage, which then launched back off the moon to reunite with the mission’s orbiter. This reunion was the first time two robotic spacecraft performed a completely automated docking outside of Earth’s orbit.
The capsule containing the samples was transferred to the return spacecraft, which left the moon’s orbit and headed homewards. As Chang’e 5 neared Earth, it released the capsule, which bounced off the atmosphere once, like a rock skipped over a lake, to slow down before entering the atmosphere and deploying its parachutes.
Finally, the capsule landed in Mongolia. Some of the will be stored at Hunan University in Changsha, China, while the rest will be distributed to researchers for analysis.
One of the most important analyses that researchers will perform is measuring the ages of the rocks in the samples and how they have been affected by the space environment over time. “We think that the area that Chang’e 5 has landed on represents one of the youngest lava flows on the surface of the moon,” says Barnes. “If we can better constrain the age of that area, then we can place much tighter constraints on the ages of surfaces all around the solar system.”
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