Today (20 July 2019) marks 50 years since Neil Armstrong took those historic steps that marked the pinnacle of human achievement to date. The Apollo 11 mission and those which followed demonstrated what humans could accomplish with sheer curiosity and determination.
The Apollo missions collected and returned approximately 380 kg of lunar rocks to Earth where they are curated by NASA and allocated to approved scientific research projects. Over the past 50 years, the Apollo lunar samples have been studied in laboratories around the world using modern analytical techniques.
From these studies, it emerged that lunar geology could be described in terms of two major rocks types: the anorthosites (named after rocks rich in a calcium-rich mineral called anorthite) that constitute the lighter areas (called Highlands) on the Moon’s surface as viewed in the night sky; and the mare basalts (named after rocks formed mainly of iron-rich minerals, which form through quick cooling of a lava) that represent the darker patches dotted across the Moon’s surface, originally named after the Latin ‘mare’ meaning ‘sea’.
Watch the video below as Tara Hayden discusses the structure of the Moon.
While investigating the Moon’s geology, scientists also looked for the presence of indigenous volatile elements in lunar samples. Volatile elements, such as carbon, nitrogen and water, are essential for life on Earth. In the interest of discovering if the Moon was ever habitable, quantifying its volatile element contents was of major importance. However, in the decades following the Apollo missions, scientists found little evidence of volatiles in the lunar samples.
Future missions to the Moon’s poles are aimed at testing whether water ice is indeed present, as this could be a valuable resource. If we can extract water while on the Moon, this will reduce the payload that the crew must take on the outbound journey.
However, this all changed only a decade ago. In 2008, Saal et al. published a paper reporting significant quantities of water in volcanic green glass beads that are formed when lava erupts energetically on to the Moon’s surface in fire fountain eruptions. This created a paradigm shift in lunar science and prompted the re-analysis of the Apollo collections using newer techniques. This led to the discoveries of substantial quantities of water in a variety of rock types, ranging from a few tens of ppm (parts per million) to up to several hundred ppm. This means that the interior of the Moon, could have significant quantities of water.
Lunar agenda, taken by ESA astronaut Alexander Gerst from the International Space Station.
Prior to Saal et al.’s discovery, lunar orbiters were detecting signs of water ice at the Moon’s poles, in craters that are permanently in shadow. Future missions to the Moon’s poles are aimed at testing whether water ice is indeed present, as this could be a valuable resource. If we can extract water while on the Moon, this will reduce the payload that the crew must take on the outbound journey.
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In order to extract water on the Moon, however, we will need technology capable of doing so. Indeed, there is ongoing research to produce such an instrument. It is anticipated that the next decade will witness a successful application of this technology which can be replicated for future crewed missions and perhaps even for developing a future Moon base.
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