Spectrometry In Space: Perseverance Engineers Revive SHERLOC Instrument on Mars Rover

For the past six months, the SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) instrument on NASA’s Perseverance Mars rover has not been operational. But after six months of diligent effort, NASA has announced that SHERLOC is once again enabling the rover to continue its search for ancient microbial life, analyzing a rock target with its spectrometer and camera for the first time since encountering an issue in January, according to an article in Space Daily (1).

Engineers at NASA's Jet Propulsion Laboratory (JPL) confirmed on June 17 that SHERLOC was able to successfully collect data. "Six months of running diagnostics, testing, imagery and data analysis, troubleshooting, and retesting couldn't come with a better conclusion," SHERLOC principal investigator Kevin Hand of JPL, told Space Daily (1).

SHERLOC uses two cameras and a laser spectrometer mounted on the rover’s robotic arm in its search for organic minerals and compounds in rocks which have been altered by water, in hopes of discovering proof of past microbial life. According to NASA (2), the rover’s spectrometer works with the cameras to examine the chemistry of the rocks encountered after a small amount of the rock is vaporized by a laser into a hot gas called "plasma,” with the spectrometer "reading" the hot gas to reveal the chemical makeup of the vaporized rock.

On January 6, a movable lens cover protecting the instrument's spectrometer and one of its cameras from dust was found to have become frozen, preventing data collection. Analysis revealed a malfunction in a small motor that was responsible for moving the protective lens cover and adjusting focus for the spectrometer and the autofocus and context imager (ACI) camera, prompting the team to start a thorough evaluation process on a duplicate SHERLOC instrument at JPL in the hope of determining how the lens cover could be moved to the open position. Among the steps taken by the team were heating the lens cover's small motor, rotating the SHERLOC instrument with the rover's robotic arm, rocking the mechanism to loosen debris, and even using the rover's percussive drill to jostle it loose. On March 3, imagery from Perseverance showed that the ACI cover had opened more than 180 degrees, clearing the imager's field of view.

"With the cover out of the way, a line of sight for the spectrometer and camera was established. We were halfway there," Kyle Uckert, SHERLOC deputy principal investigator at JPL, told Space Daily (1). "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."

The team then used the rover's robotic arm to make precise adjustments in the distance between SHERLOC and its target to achieve the best image resolution. SHERLOC was then commanded to take pictures of its calibration target to check this approach.

"The rover's robotic arm is amazing. It can be commanded in small, quarter-millimeter steps to help us evaluate SHERLOC's new focus position, and it can place SHERLOC with high accuracy on a target," Uckert said (1). "After testing first on Earth and then on Mars, we figured out 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 the proper positioning of the ACI on a Martian rock target came on May 20, and final verification that the spectrometer is functional came on June 17, confirming SHERLOC was once again fully operational.

"Mars is hard, and bringing instruments back from the brink is even harder," said Perseverance project manager Art Thompson of JPL. "But the team never gave up. With SHERLOC back online, we're continuing our explorations and sample collection with a full complement of science instruments. (1)"

The Perseverance rover is in the later stages of its fourth science campaign, looking for evidence of carbonate and olivine deposits in the "Margin Unit," an area along the inside of Jezero Crater's rim, according to Space Daily. Scientists believe that the Jezero Crater area was once flooded with water and was home to an ancient river delta (2). On Earth, carbonates typically form in the shallows of freshwater or alkaline lakes, which might also be the case for the Margin Unit, formed more than 3 billion years ago.

References

1.

Mars rover navigates rocky landscape at sunrise, desolate terrain and rover's advanced technology, capturing essence of space exploration and discovery. © ugguggu - stock.adobe.com

Oxford, C. Perseverance Engineers Revive SHERLOC Instrument on Mars Rover. Space Daily 2024. https://www.spacedaily.com/reports/Perseverance_Engineers_Revive_SHERLOC_Instrument_on_Mars_Rover_999.html (accessed 2024-06-27)

2. Mars 2020: Perseverance Rover. NASA website. https://science.nasa.gov/mission/mars-2020-perseverance/ (accessed 2024-06-27)

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