Lunar spaceship will get an improve to seize new views of the moon

Eleven years after its mission, the Lunar Reconnaissance Orbiter (LRO) is showing its age, but a recently released software update promises to breathe new life into the spacecraft. As NASA’s view of the sky over the moon, the LRO was responsible for some of the best lunar observations since the days of Apollo. This legacy can continue with this new upgrade.

The LRO, which was launched in June 2009, quickly managed to map over 98% of the lunar surface with a resolution of 100 meters per pixel. The orbiter is also known for taking incredibly high-resolution images of the Apollo landing sites, which clearly show the landers, rovers, tire tracks, and astronauts’ footprints.

LRO image of the Apollo 16 landing site. Photo credit: NASA / GSFC / Arizona State University.

In 2016, the LRO found evidence that the moon is geologically active due to tidal forces from the Earth and also because the moon is shrinking as its core cools. More recently, the LRO has been able to observe the impact sites of both the Indian Space Research Organization’s Vikram lander and SpaceIL’s Beresheet lander (both impressive and record breaking missions, despite their “explosive” endings).

However, the LRO’s monumental track record has not made them immune to problems. Its problems began in 2018 when the LRO’s aging miniature inertial measurement unit (MIMU), an instrument used to measure the rotation of the spacecraft, had to be shut down. Without the MIMU, the LRO has to rely solely on Star-Tracker for orientation. Star tracking is a viable alternative to MIMU, which uses star positions like a map to tell the spaceship which direction it is pointing.

However, in the absence of new software, the star tracking method prevented the LRO from performing the quick and complicated maneuvers required to capture lateral angle images of the moon. These side angle shots are important for two reasons. The first is that they enabled photometry, or the ability to study how surface brightness changes from different perspectives. Second, they provide the ability to create spectacular 3D imagery that gives the geographic features of the moon a sense of depth and realism that is sometimes lacking in the map-like images created through direct shooting.

Use the slider to compare two images of Aristarchus Crater captured by the LRO: the first from a side angle, the second from a straight head. Photo credit (both images): NASA / GSFC / Arizona State University.

To restore the LRO’s ability to quickly realign itself for lateral angle shots, the LRO team had to write a new algorithm they called “FastMan”, short for “Fast Maneuvering”. It went online for the first time in 2020 and has proven to be a great success so far.

One of the challenges FastMan faced was that if the star trackers were accidentally pointed at a bright object such as the sun, moon, or earth, they would lose their ability to orient the spaceship. FastMan ensures that this does not occur.

FastMan originally required input from the ground in order to be able to work with the flight software. Now it has been integrated so that FastMan can perform autonomous side view maneuvers.

The central summit of Tycho crater as seen from the LRO at an oblique angle. Photo credit: NASA / GSFC / Arizona State University.

With the installed upgrade, the LRO will continue to be scientifically active well into the next decade. Regarding the future life of the LRO, Noah Petro, Project Scientist for LRO at NASA Goddard, said that “Fuel can be our rate-limiting factor. Current estimates assume that we will have fuel on board for at least five more years, if not more. “

Although the LRO has surpassed its original mission objectives, the continued well-being of the spacecraft will continue to benefit for years to come, not least because it can support the Artemis program, which is preparing for the next human moon landing sometime this decade. Long live the LRO!

Further information: Bill Steigerwald, “Teaching an Old Spaceship New Tricks to Explore the Moon”, GSFC.

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