NASA's LADEE mission shows the force of meteoroid strikes on lunar exosphere

December 18, 2015, NASA

NASA scientists have released new findings about the moon's tenuous exosphere – the thin layer of gas surrounding the moon that's one 25-trillionth the density of Earth's atmosphere. The data reveal, for the first time, that meteoroid strikes cause a predictable increase in the abundance of two key elements within the lunar exosphere.

Physical processes such as meteoroid stream impacts, the bombardment of helium and hydrogen particles from the sun, thermal absorption, and space weathering constantly modify the moon's surface as they work within the lunar . NASA's Lunar Atmosphere and Dust Environment Explorer, or LADEE, spacecraft observed an increase in exospheric gases when the rain of meteoroid impacts increases during a stream. These interplanetary grains can hit the lunar surface at speeds exceeding 21 miles (34 kilometers) per second, releasing immense heat, and vaporizing part of the soil and meteoroids themselves.

Within this vapor are sodium and potassium gases. LADEE's Ultraviolet Visible Spectrometer (UVS) instrument measured levels of sodium and potassium around the moon every 12 hours for more than five months. These frequent readings revealed a dynamic rise of gas levels in the exosphere as meteor streams bombarded the moon, with the concentrations of both elements returning to normal background levels after the stream passed. Interestingly, the time it took to return to "normal" was dramatically different for the two gases, with potassium returning to its pre-shower state within days, while sodium took several months.

Artist’s concept of NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft in orbit above the moon. Credit: NASA Ames / Dana Berry

The findings are being presented at this week's meeting of the American Geophysical Union in San Francisco and appear in the journal Science. Researchers will incorporate these observations into exosphere models of the moon and similar bodies to help NASA unravel the mysteries of how our solar system originated and is changing over time.

"To understand the moon's exosphere requires insight into the processes controlling it, including the interaction of meteoroid showers as well as solar wind bombardment and ultraviolet radiation of the surface," said Anthony Colaprete, researcher at NASA's Ames Research Center in Moffett Field, California, and principal investigator of the UVS instrument. "Understanding how these processes modify the exosphere allows researchers to infer its original state. Since these processes are ubiquitous across the solar system, knowledge gained by examining the moon's exosphere can be applied to a range of other bodies, granting us greater insight into their evolution through time."

A majority of bodies in the solar system are small and are considered "airless," with exospheres in place of dense atmospheres. Our moon, icy moons within our solar system, the planet Mercury, asteroids and even Pluto are examples of small bodies with known exospheres that start from their surface – surface-boundary exospheres. Larger bodies, such as Earth, also have tenuous exospheres as the outermost layer of their atmospheres.

Our moon can act as a nearby laboratory for learning more about both the soil composition and the processes active in the atmospheres across our and beyond.

"These observations enable us to constrain the that contribute to the lunar exosphere," said Menelaos Sarantos of NASA's Goddard Spaceflight Center in Greenbelt, Maryland, and the University of Maryland, Baltimore County, and co-author of the paper. "We're using these findings to build new exosphere models of how the space environment interacts with the surfaces of airless bodies, which we can use to better predict the processes and behaviors around similar bodies."

LADEE was launched in September 2013 and orbited the moon for about six months. The robotic mission orbited the to gather detailed information about the , conditions near the surface, and environmental influences on lunar dust. Ames was responsible for the LADEE spacecraft design, development, testing and mission operations, in addition to managing the overall mission.

Explore further: LADEE spacecraft finds neon in lunar atmosphere

Related Stories

LADEE spacecraft finds neon in lunar atmosphere

August 17, 2015

The moon's thin atmosphere contains neon, a gas commonly used in electric signs on Earth because of its intense glow. While scientists have speculated on the presence of neon in the lunar atmosphere for decades, NASA's Lunar ...

Unexpected activity on the moon

November 30, 2015

The lunar space environment is much more active than previously assumed. The solar wind is reflected from the surface and crustal magnetic fields of the moon which has effects on for instance lunar water levels. This according ...

NASA extends moon-exploring satellite mission

February 3, 2014

( —NASA's Lunar Atmosphere and Dust Environment Explorer, or LADEE, observatory has been approved for a 28-day mission extension. The spacecraft is now expected to impact the lunar surface on or around April 21, ...

Rare full moon on Christmas Day

December 17, 2015

Not since 1977 has a full moon dawned in the skies on Christmas. But this year, a bright full moon will be an added gift for the holidays.

Is there an atmosphere on the Moon?

April 16, 2013

( —Until recently, most everyone accepted the conventional wisdom that the moon has virtually no atmosphere. Just as the discovery of water on the moon transformed our textbook knowledge of Earth's nearest celestial ...

Mercury gets a meteoroid shower from comet Encke

November 10, 2015

The planet Mercury is being pelted regularly by bits of dust from an ancient comet, a new study has concluded. This has a discernible effect in the planet's tenuous atmosphere and may lead to a new paradigm on how these airless ...

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

EPA adviser is promoting harmful ideas, scientists say

March 22, 2019

The Trump administration's reliance on industry-funded environmental specialists is again coming under fire, this time by researchers who say that Louis Anthony "Tony" Cox Jr., who leads a key Environmental Protection Agency ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.