The Moon may be off the table as the venue of future human exploration, thanks to the decision by President Obama to cancel the Constellation space exploration program, but scientists are still finding out new things about Earth's nearest neighbor.
Thanks to an examination of rock samples brought back to Earth by the Apollo astronauts, scientists have concluded that lunar water was likely deposited by comet impacts. Recently frozen lunar water confirmed in great abundance by the LCROSS impact probe and various lunar orbiters, such as NASA's Lunar Reconnaissance Orbiter and India's Chandrayaan, existing in permanently shadowed craters at the lunar poles.
James Greenwood, of Wesleyan University, has published a paper in the journal Nature Geoscience that suggests, comparing isotopes in the Apollo rock samples with those found in comets such as Hale-Bopp, Hyakutake and Halley were quite similar. Greenwood posits that a considerable amount of the lunar water was deposited on the Moon while it was being formed over four billion years ago. Comet strikes may also have created the Earth's oceans, Greenwood adds.
Meanwhile, a team of NASA scientists have re-examined data collected by seismometers deployed by the Apollo astronauts between 1969 and 1972, which returned considerable data until they were turned off in 1977.
Using modern computers used to analyze the decades-old data, NASA scientists have concluded that the Moon has an interior similar to Earth's, with a solid inner core and a molten outer core. According to MSNBC, Renee Weber of the Marshal Space Flight Center led a team processed the old data: by examining the existing catalogue of lunar seismic signals, which included more than 6,000 deep moonquakes. By processing the new data, Weber and her team were able to develop a good idea of the makeup of the Moon's interior.
"The density and size of the moon's core affects how long it would take for a moonquake to travel through it, Weber said. So the researchers could then predict when a hypothetical seismic wave would reach a certain point, which allowed them to compute the size and structure of the core with great precision."
The findings of Weber and her team have been published in the journal Science.
The remarkable aspect of both stories is how modern processing techniques can use decades old data and make new discoveries that were unimaginable when the Apollo lunar expeditions were still being undertaken. The Moon is still yielding her secrets as scientists continue to examine data gathered over the years, from the Apollo missions, as well as more recent, robotic missions.
This suggests that continued exploration, human and robotic, of the Moon, even leaving aside national security needs and commercial possibilities, is likely to yield more good science in the years and decades to come.