Earth held its breath as Perseverance attempted to core rock on Mars for the first time last month — and then everything crumbled.
The crumbling was literal. There was nothing wrong with the rover’s equipment, but the rock itself, which was too weak to withstand being cored and staying in one piece until it made it into a sample tube. It fell apart to the disappointed sighs of an entire planet. So the Roubion site was out. Next was Montdeneir, and scientists were determined to get something out of this one now that they knew what kind of rock to avoid. And they did.
Even though the first images of the second sample were inconclusive because there was not enough sunlight for its Mastcam-Z instrument to see it clearly, later tests proved that Perseverance really did succeed in coring its first intact rock sample and stashing it away for a future spacecraft to eventually pick it up from orbit (more on that here) and bring it to Earth. Perseverance project scientist Ken Farley of Caltech was thrilled.
“For our second attempt, we selected a much sturdier-looking rock and made only one change in the process,” Farley tells SYFY WIRE. “We stopped the activity between coring and taking the sample inside the rover to process. In between these steps we took multiple images down the tube to make sure something was in there.”
Turned out there was. The core is now in processing, and Perseverance should soon be transmitting evidence that the process has now been completed. Farley and his team realized it ended up being a matter of knowing when the rover came across the right rock. While the stuff at Roubion appeared usable, it could not stand up to the rover’s Sampling and Caching System at the end of its 7-foot robotic arm. The Sampling and Caching System works like your average hammer drill (with a coring bit that has a sample tube attached) to make a hole.
Because the rock at Roubion was too weak, it couldn’t even keep itself together during drilling. It fell right out of the tube after the force used to extract it basically turned it to dust. After this most recent coring, the rover moved everything toward its Mastcam-Z instrument for imaging, which didn’t initially turn out so well because of weak sunlight. Mastcam-Z takes shots during and after “percuss to ingest” mode, which involves vibrating the drill to get rid of residue and shake the sample further into its tube. There is now an actual core in there — but that isn’t all.
With the rock, Perseverance also collected an atmospheric sample of Mars that could reveal more about its composition, especially before just about all of its atmosphere was obliterated. The Red Planet that now appears desolate and barren is thought to have once been flowing with lakes and rivers. It may have had as much warmth and humidity as prehistoric Earth, and was possibly even teeming with some sort of life-forms. While Farley thought this would end up happening sometime later, Perseverance managed to surprise everyone back on the home planet and pulled it off.
“The composition of the atmosphere will tell us a lot about the history of the planet and about current processes that are occurring,” he says. “For example, it appears that Mars lost most of its atmosphere billions of years ago — as the residue of that process, the modern atmosphere can tell us how that happened.”
This and future cores will eventually land on Earth to be studied for ancient signs of habitability and life, as well as clues to the origin of not just Mars itself, but the solar system and possibly the universe. Jezero crater itself was probably once an enormous lake made out of an impact crater. Knowing that the first one of these now exists is kind of surreal. Farley and his team are now taking a careful look at the rocks in the crater and trying to make sure Perseverance will seek out rocks sturdy enough to make it through the coring process without being decimated.
“Tentative lesson: some rocks in Jezero crater are too crumbly to core without modifications to our process,” Farley says. “We are studying what modifications might work back at JPL.”