NASA’s Perseverance rover is on the hunt for gems
NASA/JPL-Caltech/ASU/MSSS
The Perseverance rover has found gems inside Martian rock. These pearl grains are made of a substance called corundum, which is also known as ruby or sapphire depending on the trace metals in it.
Ann Ollila at Los Alamos National Laboratory in New Mexico and her colleagues first detected hints of corundum while using Perseverance’s SuperCam instrument to examine a rock called the Hampden River. SuperCam has several different ways to test a material’s composition, using two different lasers to either burn off the surface or provoke luminescence, then two cameras to examine the resulting light. In both tests, the results for Hampden River were almost identical to the results from rubies measured in the laboratory, indicating the presence of small corundum grains in the rock.
As the rover drove along the rim of Jezero Crater, it left the Hampden River, and the researchers found another pebble called Coffee Cove to check out. Measurements of the makeup suggested that corundum was also present. It was the same for a third rock called Smiths Harbour. Ollila presented these findings at the Lunar and Planetary Science Conference in Texas on March 16.
These gems have never been discovered on Mars before, and it is unlikely that they formed there in the same way they do on Earth. “(Corundum) is usually associated, on Earth, with tectonism. It’s a very specific environment — you have to have a very silica-poor environment, very aluminum-rich,” Ollila said in his presentation. Mars does not have plate tectonics like Earth does, so finding corundum there was unexpected. Rather than tectonism, the Martian crust probably formed when meteorites smashed into the ground and heated and compressed the dust.
“I was very surprised,” Allan Treiman of the Lunar and Planetary Institute in Texas, who was not part of Ollila’s team, said during the conference session. “In retrospect, one might not have been, because there are aluminum-rich outcrops elsewhere on the planet and there are impacts, but I thought it was very shocking to see this.”
Because the corundum grains are so small, less than 0.2 millimeters across, it was impossible to tell in pictures whether they are rubies or sapphires and how they might look to the human eye.
“I would love to be able to pick one of these up and analyze it and see if it looks red – it’s quite disappointing that all you can see is this white pebble,” Ollila said. But when hit with the SuperCam laser, they glowed brightly.
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