Headlines > News > Lunar Reconnaissance Orbiter Spectrometer Detects Helium in Moon's Atmosphere

Lunar Reconnaissance Orbiter Spectrometer Detects Helium in Moon's Atmosphere

Published by Klaus Schmidt on Wed Aug 15, 2012 7:33 pm via: NASA
Share
More share options
Tools
Tags

Scientists using the Lyman Alpha Mapping Project (LAMP) spectrometer aboard NASA’s Lunar Reconnaissance Orbiter (LRO) have made the first spectroscopic observations of the noble gas helium in the tenuous atmosphere surrounding the moon.

These remote-sensing observations complement in situ measurements taken in 1972 by the Lunar Atmosphere Composition Experiment (LACE) deployed by Apollo 17.

The Lyman Alpha Mapping Project (LAMP) aboard LRO (shown here in a pre-flight photo) uses a novel method to peer into the perpetual darkness of the moon's so-called permanently shadowed regions. LAMP "sees" the lunar surface using the ultraviolet light from nearby space and stars, which bathes all bodies in space in a soft glow of ultraviolet light. (Credit: NASA Goddard/Debbie McCallum)

The Lyman Alpha Mapping Project (LAMP) aboard LRO (shown here in a pre-flight photo) uses a novel method to peer into the perpetual darkness of the moon's so-called permanently shadowed regions. LAMP "sees" the lunar surface using the ultraviolet light from nearby space and stars, which bathes all bodies in space in a soft glow of ultraviolet light. (Credit: NASA Goddard/Debbie McCallum)

Although designed to map the lunar surface, the LAMP team expanded its science investigation to examine the far ultraviolet emissions visible in the tenuous atmosphere above the lunar surface, detecting helium over a campaign spanning more than 50 orbits. Because helium also resides in the interplanetary background, several techniques were applied to remove signal contributions from the background helium and determine the amount of helium native to the moon. Geophysical Research Letters published this research in 2012.

With support from LRO's suite of instruments, LAMP (shown here during installation) has previously determined that hydrogen, mercury and other volatile substances are present in the permanently shaded regions (PSRs) of the moon. It has also observed PSRs are darker at far-ultraviolet wavelengths and redder than nearby surfaces that receive sunlight. These darker regions indicate "fluffy" soils, while the reddening is consistent with the presence of water frost. (Credit: NASA)

With support from LRO's suite of instruments, LAMP (shown here during installation) has previously determined that hydrogen, mercury and other volatile substances are present in the permanently shaded regions (PSRs) of the moon. It has also observed PSRs are darker at far-ultraviolet wavelengths and redder than nearby surfaces that receive sunlight. These darker regions indicate "fluffy" soils, while the reddening is consistent with the presence of water frost. (Credit: NASA)

“The question now becomes, does the helium originate from inside the moon, for example, due to radioactive decay in rocks, or from an exterior source, such as the solar wind?” says Dr. Alan Stern, LAMP principal investigator and associate vice president of the Space Science and Engineering Division at Southwest Research Institute, Boulder, Colo.

Artist's rendering of the Lunar Reconnaissance Orbiter spacecraft. Credit: NASA's Goddard Space Flight Center

Artist's rendering of the Lunar Reconnaissance Orbiter spacecraft. Credit: NASA's Goddard Space Flight Center

“If we find the solar wind is responsible, that will teach us a lot about how the same process works in other airless bodies,” says Stern.

If spacecraft observations show no such correlation, radioactive decay or other internal lunar processes could be producing helium that diffuses from the interior or that is released during lunar quakes.

The Lunar Atmosphere Composition Experiment (LACE) deployed by Apollo 17 in 1972 (shown here in a pre-flight photo) provided the first measurements of helium in the moon's atmosphere. Credit: NASA

The Lunar Atmosphere Composition Experiment (LACE) deployed by Apollo 17 in 1972 (shown here in a pre-flight photo) provided the first measurements of helium in the moon's atmosphere. Credit: NASA

“With LAMP’s global views as it moves across the moon in future observations, we’ll be in a great position to better determine the dominant source of the helium,” says Stern.

Another point for future research involves helium abundances. The LACE measurements from the 1970’s showed an increase in helium abundances as the night progressed. This could be explained by atmospheric cooling, which concentrates atoms at lower altitudes. LAMP will further build on those measurements by investigating how the abundances vary with latitude.

This composite image of the moon was constructed using Clementine data from 1994. Credit: NASA

This composite image of the moon was constructed using Clementine data from 1994. Credit: NASA

During its campaign, LACE also detected the noble gas argon on the lunar surface. Although significantly fainter to the spectrograph, LAMP also will seek argon and other gases during future observations.

“These ground-breaking measurements were enabled by our flexible operations of LRO as a Science Mission, so that we can now understand the moon in ways that were not expected when LRO was launched in 2009,” said Richard Vondrak, LRO project scientist at NASA’s Goddard Space Flight Center, Greenbelt, Md.

NASA Goddard developed and manages the LRO mission. LRO’s current Science Mission is implemented for NASA’s Science Mission Directorate. NASA’s Exploration Systems Mission Directorate sponsored LRO’s initial one-year Exploration Mission that concluded in September 2010.

No comments
Start the ball rolling by posting a comment on this article!
Leave a reply
You must be logged in to post a comment.
© 2014 The International Space Fellowship, developed by Gabitasoft Interactive. All Rights Reserved.  Privacy Policy | Terms of Use