Lamp Lights Up Helium On Moon’s Surface

A new observation made by NASA's spacecraft validates the observations made four decades ago on the lunar surface. The scientists have discovered the presence of noble gas helium in the atmosphere surrounding Moon.

This observation was made using the Lyman Alpha Mapping Project (LAMP) spectrometer aboard NASA's Lunar Reconnaissance Orbiter (LRO). This finding also confirms the measurement made by Lunar Atmosphere Composition Experiment (LACE) which was deployed by Apollo 17 astronauts in 1972.

LAMP that was originally designed to map lunar surface, later expanded its mission in examining the far ultraviolet emissions visible in the vague atmosphere that hovers above the lunar surface, indicating the presence of helium. It is known that this noble gas helium resides in the interplanetary background and several techniques were applied to remove signal contributions from the background helium and determine the amount of helium native to the Moon.

Helium gas is the second lightest element. It is mostly used to condense hydrogen and oxygen to make rocket fuel. Helium is also used as a protective gas when growing silicon and germanium crystals and when producing titanium and zirconium. It is a fantastic protective gas as it is inert (unreactive). The gas is also used in balloons, airships, blimps and is also used in deep diving ships to reduce the effect of narcosis. When combined with xenon it is used for thermoacoustic refrigeration. They are also used in the hospitals to cool superhot materials in the MRI equipment.

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

But if the researchers fail to notice such correlation with the help of the spacecraft, radioactive decay or other internal lunar processes could be producing helium that they predict might be diffused from the interior region or through lunar quakes.

"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.

The point of observation for the researchers has been the increase in helium abundance. LAMP will investigate how the abundance differs with altitude.

Researchers were amazed when LACE detected noble gas argon on the lunar surface.

"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.

These findings are being published Geophysical Research Letters.