New findings expand Apollo observations of lunar atmosphere

Jul 18, 2012
Moon. Image credit: NASA

In December 1972 the astronauts of Apollo 17-the last manned mission to the moon-deployed the Lunar Atmospheric Composition Experiment (LACE), a spectrometer designed to measure and characterize the thin lunar atmosphere. Forty years later, Stern et al. built upon those initial measurements, providing the first remotely-sensed measurement of the Moon's gaseous environment from lunar orbit. Using the Lyman Alpha Mapping Project's (LAMP's) far ultraviolet spectrograph aboard the Lunar Reconnaissance Orbiter, the authors determined the atmospheric concentration of helium.

By angling LAMP's sensors towards the lunar limb and comparing those observations against measurements of the interstellar background, the authors were able to estimate the helium concentration of the near-surface lunar environment. They calculate a density of 7,000 atoms per cubic centimeter at 120 degrees Kelvin (-244 degrees Fahrenheit), the assumed atmospheric temperature. The previous LACE observations ranged between 10,000 - 20,000 and 50,000 atoms per cubic centimeter depending on the time of day, increasing at nighttime and decreasing during the day. The nighttime decrease occurs because the atmosphere cools and contracts, yielding an increased density.

The authors suggest that the next steps should involve looking for spatial or temporal variations in lunar atmospheric helium. Such observations could help to determine whether the helium is produced locally by radioactive decay of lunar material or if it is formed from trapped and neutralized solar wind.

Explore further: Cassini watches mysterious feature evolve in Titan sea

More information: Lunar atmospheric helium detections by the LAMP UV spectrograph on the Lunar Reconnaissance Orbiter, Geophysical Research Letters, doi:10.1029/2012GL051797, 2012

add to favorites email to friend print save as pdf

Related Stories

Back to the Moon: Lunar Reconnaissance Orbiter Project

Apr 19, 2007

Of the two luminaries that dominate our sky, it is the moon that is of particular interest to the Lunar Reconnaissance Orbiter (LRO) project. The LRO will travel to the moon in late fall 2008, mapping the ...

NASA tests moon orbiter components

Jan 12, 2008

U.S. engineers are testing the components of the Lunar Reconnaissance Orbiter to make sure it is ready for its mission to the moon.

Send Your Name to the Moon Aboard LRO

May 01, 2008

NASA invites people of all ages to join the lunar exploration journey with an opportunity to send their names to the moon aboard the Lunar Reconnaissance Orbiter, or LRO, spacecraft.

Recommended for you

Cassini watches mysterious feature evolve in Titan sea

13 hours ago

(Phys.org) —NASA's Cassini spacecraft is monitoring the evolution of a mysterious feature in a large hydrocarbon sea on Saturn's moon Titan. The feature covers an area of about 100 square miles (260 square ...

MOM eyes the limb of Mars after historic arrival

21 hours ago

India's maiden interplanetary voyager, the Mars Orbiter Mission (MOM) has transmitted a breathtaking new image eyeing the limb of Mars and its atmosphere against the blackness of space.

The extremes of Earth's Late Heavy Bombardment

22 hours ago

On June 30, 1908 a bolide streaked across the sky in the region near the Podkamennaya Tunguska River in Russia. When it exploded, the airburst leveled more than 2,000 square kilometers of trees. It is now ...

User comments : 0