Resilience Wins: SHERLOC’s Mission Reborn on Mars

After six long months of very tough work, hardware that assists NASA’s Perseverance Mars rover in its search for signs of potential past life has once again been run.

NASA engineers have pulled off a lot of testing and inventive fixes with a mechanical failure that had shut down SHERLOC operations after a stuck lens cover, which included manipulating the rover’s body, opened new possibilities for resumption of exploration and data-gathering on Mars with an eye to the geological signs of past life.

For the first time since developing an issue last January, the SHERLOC — Scanning Habitable Environments with Raman & Luminescence for Organics and Chemicals instrument — aboard NASA’s Perseverance Mars rover has successfully analyzed a rock target with its spectrometer and camera. This instrument is integral to the mission seeking signs of ancient microbial life on Mars. The engineers at NASA’s Jet Propulsion Laboratory (JPL) in Southern California disclosed that on June 17, they’d heard that it was confirmed the instrument collected data okay.

“Six months of running diagnostics, testing, imagery and data analysis, troubleshooting, and retesting couldn’t come with a better conclusion,” said SHERLOC principal investigator Kevin Hand of JPL.

Imagery captured by a navigation camera aboard NASA’s Perseverance rover on Jan. 23 shows the position of a cover on the SHERLOC instrument. The cover had become stuck several weeks earlier but the rover team has since found a way to address the issue so the instrument can continue to operate. Credit: NASA/JPL-Caltech

Checking the Cover on Perseverance’s SHERLOC
Navcam imagery taken on Jan. 23 shows a location where a cover on the SHERLOC instrument was operating with a cover that became stuck many weeks ago. The rover team has since found a way to press on from the issue, so that the instrument can continue making progress in its commissioning. Credit: NASA / JPL-Caltech

Mounted to the rover’s robotic arm, SHERLOC is equipped with two cameras and a laser spectrometer to investigate altered rocks found in watery environments for organic compounds and minerals that might contain signs of past microbial life on Mars. On Jan. 6, the lens cover for one of the cameras and for an infrared spectrometer became frozen in place.

An analysis by the team led to the identification of the problem: a small motor that was supposed to move the protective lens cover, as well as handle a focus adjustment on the spectrometer, and for the Autofocus and Context Imager camera. After running several tests on possible solutions using a duplicate SHERLOC instrument at JPL, the team began an arduous, painstaking process of testing how, or whether, the lens cover might be moved into the open position.

SHERLOC Autofocus and Context Imager Lens Cover
The lens cover on SHERLOC’s – one of the tools on the end of the arm on NASA’s Perseverance Mars rover – was photographed jettisoned in this image taken by the Mastcam-Z instrument aboard the rover on May 11, 2021. CREDIT: NASA/JPL-Caltech/ASU/MSSS

SHERLOC
Among many other steps taken, this included heating the lens cover’s small motor, commanding the rover’s robotic arm to rotate the SHERLOC instrument under different orientations with supporting Mastcam-Z imagery, rocking the mechanism back and forth, which could free any debris jamming the lens cover, and even engaging the rover’s percussive drill to try jostling it loose. On March 3, imagery returned from Perseverance showed the ACI cover was open to over 180 degrees, thus allowing the field of view for SHERLOC’s Imager of EVolved Relatives to be visible and the ACI to be brought near its target.

The cover for the Autofocus and Context Imager on SHERLOC — one of the instruments aboard NASA’s Perseverance Mars rover — is seen moving in images captured by the rover’s Mastcam-Z instrument on May 11. Credit: NASA/JPL-Caltech/ASU/MSSS

SHERLOC Calibration Target Image/code Labyrinth
Perseverance’s team took this image of its calibration target using the SHERLOC instrument’s Autofocus and Context Imager on May 11 to confirm the resolution of an issue with a stuck lens cover. At the center of the target is a silhouette of the fictional detective Sherlock Holmes. Credit: NASA/JPL-Caltech

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

Like any good ophthalmologist, the team set about figuring out SHERLOC’s prescription. Since they couldn’t adjust the focus of the instrument’s optics, they relied on the rover’s robotic arm to make minute adjustments in the distance between SHERLOC and its target in order to obtain the best image resolution. SHERLOC was commanded to take pictures of its calibration target so that the team could check the effectiveness of this approach.

Perseverance’s team used the SHERLOC instrument’s Autofocus and Context Imager to capture this image of its calibration target on May 11 to confirm an issue with a stuck lens cover had been resolved. A silhouette of the fictional detective Sherlock Holmes is at the center of the target. Credit: NASA/JPL-Caltech

Calibration Target for SHERLOC
The calibration target for SHERLOC, one of the instruments aboard NASA’s Perseverance Mars rover, includes a slice of Martian meteorite plus spacesuit materials including helmet-visor material that doubles as a geocache target. Credit: NASA/JPL-Caltech
“The rover’s robotic arm is pretty smokin’.”. It can be ordered in small, quarter-millimeter steps to assist us in assessing the new focus position of SHERLOC, and it can do that with high precision at a target location,” Uckert added. “After experimenting first on Earth and then on Mars, we figured out that the best distance a robotic arm can place the SHERLOC is about 40 millimeters,” or 1.58 inches. “At that distance, the data we collect should be as good as ever.”

Confirmation of that fine positioning of the ACI on a Martian rock target came down on May 20. Verification on June 17 that the spectrometer is also functional checked the team’s last box, confirming that SHERLOC is operational.

The calibration target for SHERLOC, one of the instruments aboard NASA’s Perseverance Mars rover, features a slice of Martian meteorite, plus spacesuit materials, including helmet-visor material that doubles as a geocache target. Credit: NASA/JPL-Caltech

Perseverance’s Abrasion Patch at “Walhalla Glades.
This NASA’s Perseverance rover image shows data it collected on the “Walhalla Glades” abrasion of the “Bright Angel” region of Jezero Crater taken with a front Hazard Avoidance Camera on June 14. The close-up image was taken by the WATSON camera on the SHERLOC instrument, located close to the surface of Mars. Credits: NASA/JPL-Caltech

This image of NASA’s Perseverance rover gathering data on the “Walhalla Glades” abrasion was taken in the “Bright Angel” region of Jezero Crater by one of the rover’s front hazard avoidance cameras on June 14. The WATSON camera on the SHERLOC instrument is closest to the Martian surface. Credit: NASA/JPL-Caltech

“Mars is hard, and bringing instruments back from the brink is even harder,” said JPL Perseverance Project Manager Art Thompson. “But the team never gave up. With SHERLOC back online, we’re continuing our explorations and sample collection with a full suite of science instruments.”

Perseverance is well into its fourth science campaign, exploring the “Margin Unit”—the area inside Jezero Crater’s rim—for signs of carbonate and olivine deposits. Back on Earth, carbonates mostly precipitate out in the shallows of freshwater or alkaline lakes. One hypothesis is that that may indeed have been the case for the Margin Unit, now several billion years old.

Mars 2020 Perseverance Mission
The NASA Mars 2020 Perseverance mission was launched to search for signs of ancient life and collect samples of rock and soil to be returned to Earth.

Perseverance landed on Mars, in the Jezero Crater, said to have once hosted an ancient river delta, on February 18, 2021. It is also pioneering the technology that will be needed in the future for the human and robotic exploration of Mars. The goals are centrally based on research into the climate and geology of Mars, the search for signs of life in the past, and the collection of samples from the planet with the view of preparing for human exploration. Perseverance carries, in addition to a suite of science instruments, the Ingenuity helicopter, which will perform a powered, controlled flight on another planet for the first time in history.

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