As NASA’s Perseverance spacecraft continues on its journey to Mars, scientists at the Jet Propulsion Laboratory in Pasadena Monday explained how the rover’s laser retroreflectors could be used to learn more about the Red Planet.

Managed for NASA by JPL, a division of Caltech, the Mars 2020 Perseverance — which launched July 30 and is scheduled to land on Mars on Feb. 18, 2021 — is one of a few Mars spacecraft carrying a palm-size Laser Retroreflector Array (LaRA) that could be used to better understand the planet and improve calculations for safer landings in the future, scientists said.

Such retroreflector devices have been used before by Apollo astronauts who landed on the moon, where they set up small arrays of mirrors and then had scientists on the Earth aim lasers at them to calculate the time it took for the beams to return. The practice provided precise measurements of the moon’s orbit and shape.

Someday, lasers from Earth might also be used to take measurements of Mars, and the retroreflectors carried on Perseverance will be ready and waiting, scientists said.

“While there is currently no laser in the works for this sort of Mars research, the devices are geared toward the future: Reflectors like these could one day enable scientists conducting what is called laser-ranging research to measure the position of a rover on the Martian surface, test Einstein’s theory of general relativity, and help make future landings on the Red Planet more precise,” according to NASA.

Simone Dell’Agnello, who led development of the retroreflectors at Italy’s National Institute for Nuclear Physics, which built them on behalf of the Italian Space Agency, said the “shiny” and “simple” devices are “pointlike position markers” that require no maintenance and will work for decades.

The devices work a lot like bike reflectors, bouncing light back in the direction of its source. Perseverance’s LaRA, for example, is a two-inch-wide dome speckled with half-inch holes containing glass cells. In each cell, three mirrored faces are positioned at 90-degree angles so that light entering the holes is directed back to where it came from.

“This kind of science is important for understanding how gravity shapes our solar system, the whole universe, and ultimately the roles of dark matter and dark energy,” Dell’Agnello said.

The Mars 2020 Perseverance rover is part of a larger NASA’s Mars Exploration Program that includes missions to the moon as a way to prepare for human exploration of the Red Planet. A key objective for Perseverance’s mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will also characterize the planet’s climate and geology and collect and cache Martian rocks and soil samples to be retrieved in future missions.

For more about Perseverance or to see the spacecraft’s progress in real time, visit

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