The recent discovery was made using a NASA orbiter

Aug 16, 2012 09:00 GMT  ·  By

According to the latest scientific observations made using the NASA Lunar Reconnaissance Orbiter (LRO), the tenuous atmosphere surrounding Earth's natural satellite contains small amounts of helium.

Signs that the noble gas persists in the lunar exosphere were discovered using the LRO Lyman Alpha Mapping Project (LAMP) spectrometer instrument. These are the first spectroscopic observations of helium ever made on the Moon.

One of the most interesting aspects of the new research is that it complements scientific results returned to Earth by the Lunar Atmosphere Composition Experiment (LACE), which was deployed on the satellite's surface by Apollo 17 astronauts, back in 1972.

NASA experts say that LAMP was not originally developed for atmospheric studies, but for mapping the lunar surface. However, during the course of its mission, scientists figured out that they can use its far-ultraviolet detectors to scan the thin lunar atmosphere.

The campaign that ultimately revealed the existence of helium in the exosphere took 50 orbits to complete. Establishing that the chemical is actually present around the Moon was a difficult task, because helium also exists in the interplanetary background.

As such, investigators had to use a number of techniques to eliminate these contaminating signals, while at the same time maintaining LAMP's sensitivity at sufficiently-high levels to detect the element.

Full details of the investigation were published in a recent issue of the esteemed scientific journal Geophysical Research Letters. The paper suggests radioactive decay or other internal lunar processes as the main source of atmospheric helium.

“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?” Dr. Alan Stern says.

“If we find the solar wind is responsible, that will teach us a lot about how the same process works in other airless bodies,” adds the expert, the principal investigator for the LAMP instrument.

Stern is also the associate vice president of the Boulder, Colorado-based Southwest Research Institute's (SwRI) Space Science and Engineering Division. “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,” he concludes.