Categories: MoonNASA

Moon’s Variable Gravity Came From Ancient Impacts

The moon’s gravity has been a headache ever since the Apollo era. Areas of “mass concentration” or mascons, discovered in 1968, affected spacecraft orbits and made landing on Earth’s neighbor a tricky challenge.

The phenomenon has puzzled scientists, but new data shows that mascons might have come to be after asteroids or comets hit the moon a long time ago.

For nine months last year, until their mission ended with a deliberate crash on a moon mountain, twin washing-machine sized spacecraft Ebb and Flow circled the planet. Their work was known as the GRAIL mission (also known as Gravity Recovery and Interior Laboratory.) As they orbited together, gravity changes in the moon below them slightly changed their distances to each other — sometimes closer, sometimes further.

This allowed scientists to map out the mascons to high precision once they combined that information with computer models of big asteroid impacts as well as how craters on the moon evolved.

Craters on the Moon. Image credit: NASA

Mascons, which are invisible on the surface but appear in gravity maps as a sort of bulls-eye, arise “as a natural consequence of crater excavation, collapse and cooling following an impact,” NASA stated.

The center of the bulls-eye has stronger gravity, with a ring of weaker gravity surrounding the bulls-eye, and then another ring of strong gravity surrounding the bulls-eye and inner ring.

“GRAIL data confirm that lunar mascons were generated when large asteroids or comets impacted the ancient moon, when its interior was much hotter than it is now,” stated Jay Melosh, lead researcher and a GRAIL co-investigator at Purdue University.

“We believe the data from GRAIL show how the moon’s light crust and dense mantle combined with the shock of a large impact to create the distinctive pattern of density anomalies that we recognize as mascons.”

What’s more, researchers expect they’ll be able to apply that understanding to Mercury and Mars, as mascons were also discovered on those terrestrial planets.

The findings appeared in the May 30 edition of Science. You can read the entire article here.

Source: NASA

Elizabeth Howell

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

Recent Posts

Did You Hear Webb Found Life on an Exoplanet? Not so Fast…

The JWST is astronomers' best tool for probing exoplanet atmospheres. Its capable instruments can dissect…

3 hours ago

Vera Rubin’s Primary Mirror Gets its First Reflective Coating

First light for the Vera Rubin Observatory (VRO) is quickly approaching and the telescope is…

8 hours ago

Two Stars in a Binary System are Very Different. It's Because There Used to be Three

A beautiful nebula in the southern hemisphere with a binary star at it's center seems…

1 day ago

The Highest Observatory in the World Comes Online

The history of astronomy and observatories is full of stories about astronomers going higher and…

1 day ago

Is the JWST Now an Interplanetary Meteorologist?

The JWST keeps one-upping itself. In the telescope's latest act of outdoing itself, it examined…

1 day ago

Solar Orbiter Takes a Mind-Boggling Video of the Sun

You've seen the Sun, but you've never seen the Sun like this. This single frame…

1 day ago