If You Could See Gamma Rays From Earth

The Moon as you have never seen it before. If your eyes could see gamma rays, you might see a colorful Moon, in this case, reflecting areas rich in the element thorium, where red represents a high concentration, and purple, low. You would also have to be viewing the Moon from a spacecraft because this is not the side of the Moon that always faces Earth. This view is from the east, 120 degrees east longitude, to be exact, so the left side faces Earth and on the right is part of the far side. This view is important to Jolliff because it highlights the Compton-Belkovich area, the small hot spot in the upper left, as well as the giant South Pole-Aitken basin on the lower right, which also features a higher thorium concentration than the surroundings.

Jolliff is the principal investigator of a mission concept called MoonRise that would land on the Moon’s far side and return samples from the South Pole-Aitken basin. In 2011, MoonRise was a finalist for NASA’s next New Frontiers mission. Although not selected in this round, the mission concept remains a high science priority for Solar System exploration.

The base image shown here is from the Lunar Reconnaissance Orbiter’s Wide Angle Camera, for which Jolliff is a member of the science team. The base image is part of a global mosaic of over 15,000 individual images acquired between November 2009 and February 2011 by the LRO spacecraft. The color of the thorium overlay comes from the work of Washington University alumnus David Lawrence, PhD ’96, who was a member of the Lunar Prospector (1998) gamma-ray spectrometer team and who is a colleague of Jolliff’s.

Credit for the base image: (LRO WAC) is NASA/GSFC/Arizona State University.
Credit for the thorium data used to make the overlay; Lawrence et al., 2000, JGR 105.

Full reference: Lawrence D. J., Feldman W. C., Barraclough B. L., Binder A. B., Elphic R. C., Maurice S., Miller M. C., and Prettyman T. H. (2000) Thorium abundances on the lunar surface. J. Geophys. Res. 105, 20, 307-20, 331.

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