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NASA’s LRO shows effects of Earth’s gravity on the Moon

Black and White image of the Earth as seen by the Apollo 8 crew from the Moon photo credit Bill Anders / NASA posted on SpaceFlight Insider

The Moon has been impacted by the Earth’s gravitational pull – something revealed in greater detail by NASA’s Lunar Reconnaissance Orbiter.
Image Credit: Bill Anders / NASA

Just as the Moon’s gravity influences the Earth, mostly visible through ocean tides, the opposite is also true. As a binary system, the Earth and Moon actually influence each other. A new report from NASA indicates that we now have evidence of just how much influence Earth has on our closest neighbor. NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft data shows that Earth’s gravity has influenced the orientation of thousands of faults that form in the lunar surface as the Moon shrinks.

The faults investigated during this study are small, typically only a few tens of yards (meters) high and less than 6 miles (10 km) long. Scientists think these faults are formed by the Moon shrinking in size as the hot core cools and contracts. When that happens, areas of the Moon’s crust buckle and form the faults. Their locations on the surface appear to be random, but they are rather evenly distributed.

Thousands of young, lobate thrust fault scarps have been revealed in Reconnaissance Orbiter Camera images (LROC). Lobate scarps like the one shown here are like stair-steps in the landscape formed when crustal materials are pushed together, break and are thrust upward along a fault forming a cliff. Cooling of the still hot lunar interior is causing the Moon to shrink, but the pattern of orientations of the scarps indicate that tidal forces are contributing to the formation of the young faults. Image Credit: NASA/LRO/Arizona State University/Smithsonian Institution

Thousands of young, fault scarps have been revealed in Reconnaissance Orbiter Camera images (LROC). Image Credit: NASA / LRO / Arizona State University / Smithsonian Institution

More than 3,000 of these “lobate scarps” as they are called have been discovered so far.

LRO has mapped more than three-quarters of the Moon’s surface in high resolution allowing for these and other discoveries.

In 2010, only 70 of these faults were known to exist. Fourteen of them had been found using LRO’s Narrow Angle Camera (NAC) with the remainder located using the limited high-resolution Apollo Panoramic Camera photographs.

“The discovery of so many previously undetected tectonic features as our LROC high-resolution image coverage continues to grow is truly remarkable,” said Mark Robinson of Arizona State University, co-author and LROC principal investigator. “Early on in the mission we suspected that tidal forces played a role in the formation of tectonic features, but we did not have enough coverage to make any conclusive statements. Now that we have NAC images with appropriate lighting for more than half of the Moon, structural patterns are starting to come into focus.”

Many of these faults should form without any outside influence as the Moon contracts. Without influence from Earth, the orientation of these faults should be completely random. However, when scientists modeled the effects of lunar contraction, the model did not line up with the observations. Once the Earth’s tidal forces were added to the model, the predictions and the observations agreed.

“With LRO we’ve been able to study the Moon globally in detail not yet possible with any other body in the Solar System beyond Earth, and the LRO data set enables us to tease out subtle but important processes that would otherwise remain hidden,” said John Keller, LRO Project Scientist at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

LRO was launched on June 18, 2009, with a planned mission duration of one year and a proposed 5-year extension, if the orbiter remained operational. The 4,200 pound (1,900 kg) spacecraft reached lunar orbit on June 23 of that same year.

Since its launch the LRO has collected volumes of data on the Moon, increasing our knowledge of Earth’s only known natural satellite. Currently, LRO is being considered for a second mission extension. However, according to The Science Times, both LRO and NASA’s Mars Exploration Rover Opportunity are being considered for cancellation so the funds for these missions can be used elsewhere. According to a March 2015 report by Leonard David on, the budgets for LRO and Opportunity are zeroed out in President Obama’s 2016 fiscal budget request for NASA.

The LRO program is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, under the Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville for the Science Mission Directorate at NASA Headquarters in Washington, D.C.


Joe Latrell is a life-long avid space enthusiast having created his own rocket company in Roswell, NM in addition to other consumer space endeavors. He continues to design, build and launch his own rockets and has a passion to see the next generation excited about the opportunities of space exploration. Joe lends his experiences from the corporate and small business arenas to organizations such as Teachers In Space, Inc. He is also actively engaged in his church investing his many skills to assist this and other non-profit endeavors.

Reader Comments

I’m sorry, but the mystery here to me is why they expected a model that didn’t take the tidal forces from the Earth into account to be accurate at all. I’ve become increasingly aware that many of the models in use are vastly oversimplified, and then they’re surprised as if they’ve made a discovery when they make a more accurate model and it more accurately reflects observation.

eduard l goldschagg

Is just anybody and everybody allowed anywhere to design, build and launch rockets?

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