An analysis of moon rocks collected during the Apollo missions has found much higher levels of water than scientists had expected. The study increases the possibility that there are significant deposits of water trapped in rocks at the moon’s poles, which would be invaluable for astronauts setting up a future permanent base.
Finding water was a surprise because scientists believe the moon formed when a Mars-sized planet collided with the infant Earth.
The impact threw up huge amounts of molten rock that formed the moon, but in the process volatile substances such as water would have been lost into space.
”Most people believed that the moon was dry,” said Alberto Saal at Brown University in Rhode Island, who was part of the team that did the research. ”People had tried to measure for 40 years and couldn’t see any evidence for water … they were not convinced we were doing something worthwhile.”
He and his colleagues used a new and extremely sensitive technique to analyse rocks collected during the Apollo 15 mission in 1971 and the last visit by people to the moon, Apollo 17 in 1972. Since being brought back to Earth the rocks have been kept in nitrogen gas at the Johnson Space Centre in Houston, Texas.
Saal’s analysis involved polishing tiny grains of volcanic glass in the rocks to get to the chemical composition inside. Any chemicals on the outside could have been deposited after the minerals cooled in eruptions on the moon around two billion years ago.
Crucially, the concentration of water was highest in the centre of the samples and became progressively lower towards the outside, proving that the water was in the original rocks and not deposited later by contamination from asteroids or during the samples’ return to Earth.
The research is published in Thursday’s issue of the journal Nature.
The finding will give new impetus to two Nasa missions seeking water deposits on the moon. The Lunar Reconnaissance Orbiter, due to launch later this year, is hunting for water at the poles, while the Lunar Crater Observation and Sensing Satellite‘s primary objective is to look for water ice. It is due to launch next year.
Finding water is crucial to Nasa’s plans for moon exploration. ”This could be really important if you want to put a base [on the moon],” said Saal. The extracted water could be used for thirsty astronauts and to create hydrogen to use as fuel.
Professor John Zarnecki, a space scientist at the Open University, said the analysis would also provide crucial evidence about the formation of the early solar system. ”It’s like a sort of detective story in which the crime happened 4,5-billion years ago. On Earth all the evidence has gone, but on the moon there is evidence of what went on,” he said. ”Because the moon has been relatively inert and not much has happened we can actually use it as an indicator of what happened in the early history of the solar system, and of course that means what happened to us.”
The action of tectonic plates on Earth means that rocks from Earth’s early history have mostly been drawn down into the mantle at geological faults.
Zarnecki also said the research was an example of the impressive ongoing scientific legacy of the Apollo missions. ”Most people would imagine that you bring the stuff back, do the analysis over a couple of years then that’s it,” he said, ”[but] we are still getting great science from stuff collected 35 years ago.”
What did Apollo do for us?
Many people believe that non-stick frying pans were one of the Apollo programme’s technological spin-offs. That is an urban myth, but Nasa claims that plenty of other technologies used on Apollo have made their way into our everyday lives.
The cordless drill
Apollo astronauts used a self-contained drill to extract rock samples on the moon. Refinement has led to cordless drills and vacuum cleaners.
Time keeping
Electronically-stimulated quartz crystals kept the Apollo astronauts on time. They are now used in millions of quartz clocks.
Water purification
The Apollo mission used a new purification technology based on silver ions, rather than chlorine or bromine. It is now used to keep pools and spas bacteria-free.
Solar energy
Technology developed to power the Apollo craft using the sun’s energy directly is now used on Earth. – guardian.co.uk