In the future, making precision landings on the rocky, rocky, cratered surface of the Moon won’t be that difficult. At least, that’s the goal of NASA’s Lunar Retroreflector Array (LRA) program, an initiative that works in conjunction with U.S. and foreign Moon landing attempts. The LRA consists of a dome-shaped device with small glass prismatic retroreflectors on top. This device is then placed on the lander and delivered to the surface of the moon.

By reflecting laser light from orbiting and other incoming spacecraft, the LRA could serve as a permanent position marker on the Moon for decades to come. However, it was difficult to paint the lunar landscape with these devices.

Astrobotic’s custom-built Peregrine lander is one of NASA’s Commercial Lunar Payload Services (CLPS) partners, allowing commercial companies to fly the space agency’s scientific instruments to the moon.

NASA’s LRA was on the now-troubled Astrobotic lunar lander. This lander experienced problems shortly after launch, ending any hope of landing safely on the moon. But there is hope for an upcoming landing attempt of Japan’s Lunar Exploration Intelligent Lander (SLIM); Another one will land on January 20. It also carries an LRA provided by NASA.

LRAs will be carried by promising CLPS-supported lunar missions such as the Intuitive Machines Nova-C lander. There’s also the Astrobotic Griffin lander, which will also carry the LRA—quite a tall order since it carries NASA’s Volatile Exploration Polar Exploration Rover, or VIPER. But don’t forget the LRA, which was delivered to the moon by India’s successful Chandrayaan-3 lander last August.

A few important points

Daniel Cremons, deputy principal investigator for NASA’s Goddard Spaceflight Laser Retroreflector Array, explains that the LRA payload belongs to the CLPS program, but the LRA units provided to international partners were created under international memorandums of understanding signed between NASA and the relevant space agencies. Centre. in Greenbelt, Maryland.

Each LRA has a separate location marker on the surface, Cremons says.

“Just as we use multiple landmarks to navigate our daily lives on Earth, having more location markers spread across the lunar surface makes it easier and faster to determine your own location in lunar orbit,” Cremons says.

Cremons adds that the LRA project defines “operational” as an LRA lander that lands safely on the lunar surface. [індійський] “Chandrayaan-3 is the only unit currently operational.”

Cremons also helped integrate the LRA onto the SpaceIL Beresheet lander in November 2018. Beresheet was Israel’s first lunar mission and the first attempt by a private company to land on the moon. However, this spacecraft was lost during the landing attempt in April 2019.

LRA requires no power

There is a small team at NASA Goddard Space Flight Center handling the design, construction and flight capability of the small LRA. According to Cremons, the LRA units currently flying and involved in future CLPS missions were produced in a single batch in 2019. “The LRA design has been optimized to operate the laser from orbit to a lander or rover on the planet’s surface.”

The Laser Retroreflector Array (LRA) is too small to be usable from Earth. They are designed to use laser light reflected from a laser altimeter, or LIDAR, on a spacecraft orbiting the Moon or coming to a complete stop on the Moon’s surface. The LRA consists of eight small reflectors mounted on a small, elongated hemispherical platform. The total weight of the LRA is 20 grams and does not require power.

birth stage

According to the LRA documentation, “retroreflectors, unlike simple plane mirrors, reflect radiation back to its source from a wide range of angles with minimal scattering and a brighter reflection.”

On the US side, another LRA is being carried by Intuitive Machines’ Nova-C lander, which is scheduled to land on the rim of the Malapert A crater near the moon’s south pole. The Nova-C lander is expected to be launched on a Falcon-9 rocket during the IM-1 mission later this year.

As Intuitive Machines points out, LRAs are useful as precise landmarks for orientation and navigation throughout a lunar day or night. “Multiple LRAs surrounding the landing site can serve as precise landmarks to guide incoming landers and help achieve an autonomous and safe landing,” the company explains.

Cremons says the vision is for future orbiters to be equipped with a laser ranging system that could regularly measure distances to LRA units to refine the spacecraft’s orbit around the moon or calibrate guidance controls.

“LRA will be particularly useful at or near the Moon’s south pole, where image navigation is difficult due to lighting conditions,” says Cremons. “As the LRA is designed to operate for decades, I am sure there are opportunities to leverage the LRA ‘network’ that we have not considered in this new phase.”