Helium Found In Moon’s Atmosphere.

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

Remember when you were a kid and lost a balloon? You’d see it fly off into the empty sky and wonder if it would make it to space. They disappeared outa sight!

We may not be kids any more, but we just might have located where some of the gas went! Now scientists utilizing the Lyman Alpha Mapping Project (LAMP) spectrometer located on NASA’s Lunar Reconnaissance Orbiter (LRO) have made a unique spectroscopic observation… they’ve seen evidence of helium in the Moon’s thin atmosphere. 

While the LAMP equipment was originally designed to map the lunar surface, the researchers decided to put it to further use by investigating ultraviolet emissions seen just above the lunar surface. The measurements picked up the sign of the noble gas, helium, in more than 50 orbits. These indicators furthered solidified the presence of helium – a presence detected by remote-sensing observations taken in 1972 by the Lunar Atmosphere Composition Experiment (LACE) deployed by Apollo 17. However, because helium exists nearly everywhere, like light, the astronomers had to be very careful to separate its spectral signal from the background.

“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, Colorado.

“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 further observations show there isn’t any correlation, radioactive decay or other internal lunar processes might responsible for the helium signature. For example, it could be released during period “lunar quakes”, or simply diffused from the interior.

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)

“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.

On a curious note, the helium content changes as lunar day turns to lunar night. According to the LACE measurements taken about 4 decades ago, the helium content increases with darkness. This may be due to atmospheric cooling, an action which concentrates atoms at lower altitudes. Now LAMP’s ability to study at different latitudes will compile more information on those earlier measurements. However, helium isn’t all that was discovered! LAMP also picked up the signature of argon. Although it was faint, it’s a step in a new direction and LAMP will continue to look for more surprises in the future.

“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, Maryland.

Original Story Source: NASA Mission News.