Some fifty years ago, the Apollo Program sent the first astronauts to the Moon. In addition to the many science experiments they conducted on the surface, the Apollo astronauts brought back samples of lunar rock for analysis. The Soviet Luna program sent several robotic missions to the Moon around the same time that conducted sample-return missions. The examination of these rocks revealed a great deal about the composition of the Moon and led to new theories about the formation and evolution of the Earth-Moon system.
For example, analysis of the rocks revealed that the Earth and the Moon are similarly composed of silicate minerals and metals. This led to theories that the Moon’s interior is similarly divided into a silicate mantle and crust and a metallic core. However, many aspects of this theory, like the structure of the core (solid or molten?), have been debated for decades. According to new findings by a team of French scientists, it is now a scientific certainty that the Moon’s innermost region consists of a solid inner core surrounded by a molten outer core (just like Earth’s).
Fifty years ago, NASA and the Soviet space program conducted the first sample-return missions from the Moon. This included lunar rocks brought back to Earth by the Apollo astronauts and those obtained by robotic missions that were part of the Soviet Luna Program. The analysis of these rocks revealed a great deal about the Moon’s composition, formation, and geological history. In particular, scientists concluded that the rocks were formed from volcanic eruptions more than three billion years ago.
In recent years, there has been a resurgence in lunar exploration as NASA and other space agencies have sent robotic missions to the Moon (in preparation for crewed missions). For instance, China has sent multiple orbiters, landers, and rovers to the Moon as part of the Chang’e program, including sample-return missions. A new study led by planetary scientists from the Chinese Academy of Sciences (CAS) analyzed samples obtained by the Chang’e-5 rover dated to two billion years ago. Their research could provide valuable insight into how young volcanism shaped the lunar surface.
NASA’s Apollo missions to the Moon brought back about 382 kilograms (842 pounds) of samples, including rocks, rock cores, rock, pebbles, sand, and dust. Scientists have studied those samples intently over the decades and have learned a lot. But they haven’t studied all of the samples.
In an impressive act of foresight, NASA left some of the samples unopened and in pristine condition. Why? Because they knew the technology used to study the samples would only improve over the decades.
China’s Chang’e-5 lunar lander retrieved about 1.7 kilograms (3.81 pounds) of samples from the Moon, according to the China National Space Administration (CNSA). The Chang’e-5 sample return capsule landed in China’s Inner Mongolia region on December 16, 2020, successfully capping a 23-day odyssey that brought back the first lunar rocks since 1976.