Detective work allows Perseverance team to revive SHERLOC instrument

After six months of effort, an instrument that helps the Mars rover search for potential signs of ancient microbial life is back in operation.

The SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organic and Chemical Compounds) instrument aboard NASA’s Perseverance Mars rover has analyzed a rock target with its spectrometer and camera for the first time since encountering a problem last January. The instrument plays a key role in the mission’s search for signs of ancient microbial life on Mars. Engineers at NASA’s Jet Propulsion Laboratory in Southern California confirmed on June 17 that the instrument was successful in collecting data.

“Six months of running diagnostics, testing, image and data analysis, troubleshooting, and new testing could not yield a better conclusion,” said SHERLOC principal investigator Kevin Hand of JPL.

Mounted on the rover’s robotic arm, SHERLOC uses two cameras and a laser spectrometer to search for organic compounds and minerals in rocks that have been altered in aqueous environments and may reveal signs of past microbial life. On January 6, a moving lens cover designed to protect the instrument’s spectrometer and one of its cameras from dust froze in a position that prevented SHERLOC from collecting data.

Analysis by the SHERLOC team pointed to the malfunction of a small motor responsible for moving the protective lens cover, as well as adjusting the focus of the spectrometer and the Autofocus and Context Imager (ACI) camera. Testing potential solutions on a duplicate SHERLOC instrument at JPL, the team began a long and meticulous evaluation process to see if and how the lens cover could be moved to the open position.

Among many other measures taken, the team attempted to heat up the small motor in the lens cover, commanding the rover’s robotic arm to rotate the SHERLOC instrument in different orientations with supporting Mastcam-Z images, rocking the mechanism back and forth. to loosen any debris that could block the lens. take cover, and even activate the rover’s percussion drill to try to free it. On March 3, images returned by Perseverance showed that ACI’s shroud had opened more than 180 degrees, clearing the imager’s field of view and allowing ACI to position itself close to its target.

“With the cover removed, a line of sight was established for the spectrometer and camera. We were halfway there,” said Kyle Uckert, deputy principal investigator for SHERLOC at JPL. “We still needed a way to focus the instrument on a target. Without focusing, SHERLOC images would be blurry and the spectral signal would be weak.”

Like any good ophthalmologist, the team set out to determine the prescription for SHERLOC. Since they couldn’t adjust the focus of the instrument’s optics, they relied on the rover’s robotic arm to make minute adjustments to the distance between SHERLOC and its target to obtain the best image resolution. SHERLOC was instructed to take photographs of its calibration target so the team could test the effectiveness of this approach.

“The rover’s robotic arm is amazing. “It can be controlled in small steps of a quarter of a millimeter to help us evaluate SHERLOC’s new focus position and can place SHERLOC with great precision on a target,” Uckert said. “After testing first on Earth and then on Mars, we found that the best distance for the robotic arm to place SHERLOC is about 40 millimeters,” or 1.58 inches. “At that distance, the data we collect should be as good as ever.”

Confirmation of this precise positioning of the ACI on a Martian rocky target came on May 20. The June 17 verification that the spectrometer also works checked the team’s last box, confirming that SHERLOC is operational.

“Mars is difficult, and recovering instruments from the edge is even more difficult,” said Perseverance project manager Art Thompson of JPL. “But the team never gave up. “With SHERLOC back online, we continue our explorations and sample collection with a full complement of scientific instruments.”

Perseverance is in the late stages of its fourth science campaign, searching for evidence of carbonate and olivine deposits in the “Margin Unit,” an area along the interior rim of Jezero Crater. On Earth, carbonates typically form in the shallow waters of freshwater or alkaline lakes. It is hypothesized that this could also be the case for the Margin Unit, which formed more than 3 billion years ago.

A key goal of Perseverance’s Mars mission is astrobiology, including caching samples that may contain signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and store Martian rocks and regolith.

Later NASA missions, in cooperation with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis.

The Mars 2020 Perseverance mission is part of NASA’s Moon-to-Mars exploration approach, which includes Artemis missions to the Moon that will help prepare for human exploration of the Red Planet.

NASA’s Jet Propulsion Laboratory, managed by Caltech for the agency, built and manages operations of the Perseverance rover.

For more information on perseverance:

DC Eagle
Jet Propulsion Laboratory, Pasadena, California.
[email protected]

Karen Fox/Charles Blue
NASA Headquarters
202-385-1600 / 202-802-5345
[email protected] / [email protected]


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