NASA's Perseverance Rover reached a new milestone last week in its search for extraterrestrial intelligence. It drilled into Mars to find a rock plug that could be used to fuel a rocket to bring back scientists from Earth. NASA scientists received data early August 6. It indicated that the robot had successfully drilled into Mars. A photo showed even a dust heap around the borehole.In a blog post yesterday, Louise Jandura wrote that what followed was a rollercoaster ride of emotions. Although data suggested that Perseverance had placed a tube of sample into its stomach for storage, the tube was actually empty. Jandura said that while it took some time for the reality to sink in Jandura quickly switched to investigation mode. It is what we do. It is the foundation of science and engineering.The team now has some clues about what went wrong in the case of what Katie Stack Morgan (deputy project scientist for Mars 2020) calls the "missing core" situation.She says that although we've demonstrated sample caching, the tube has no core. It is impossible that all these steps have been completed perfectly and with no problems, but the tube has no core.One theory was that the rover simply dropped the core sample. There were no broken pieces. Stack Morgan also stated that the tube was clean and not dusty. This suggests that perhaps there was nothing that could have gotten in the tube.NASA scientists believe that the core was actually pulverized during drilling, and then scattered around borehole. Stack Morgan says that this would explain why there are no pieces in the hole, and why they don't appear on the ground. They have basically become part the cutting. We began to wonder why this happened, as it is not something that engineers observed in their extensive test set of rocks they had cored before launch.Perseverance is drilling at Jezero Crater. This crater used to hold a lake and may have been home for ancient microbial life. It relies on Ingenuity, a Mars helicopter, to find the best places to dig. The rover will give vital clues to the geological history and history of Mars by digging beneath the rock, rather than just sampling the dust. Curiosity, the 2012 Mars rover, also drilled. However, it was built to grind rock rather than extract cores. NASA engineers need samples to observe the rock as it is laid so that they can examine it for signs of life. For instance, microbes leave behind distinctive minerals.AdvertisementPerseverance's drilling process begins within the rover, in the section known as the adaptive caching assembly. A robotic arm removes a tube from storage and inserts it in the bit carousel. This is a storage box for all Perseverance's coring bits. The tube is then presented to the 7-foot-long drill arm by rotating the carousel. It's roughly the same size and shape as a laboratory tube. Jessica Samuels, Perseverance's surface mission manager, told us that the coring bit has the tube inside. This was before the first drilling attempt. Now we are ready to actually obtain the sample.The larger robot arm uses a drill to extract the rock. It rotates in the ground like an apple corer and then hammers into it. The rover continuously monitors its progress while it drills. The data is fed into an algorithm that adjusts drilling to increase or decrease hammering. The robot must break off the rock sample once it has bored enough to actually move the drill. Samuels said that the core-break motion is caused by the tube in the coring bit shifting to one side.The robot should be able to bring up a piece of Mars that is chalk-sized. Perseverance will continue this process several times more, taking multiple samples from Mars' crater. It's like taking a blood sample. The phlebotomist takes out the tubes and swaps them in as they fill up. Only Perseverance swaps containers as they fill up with rock.After filling a tube, the drilling arm places it in the bit carousel of the adaptive caching assembly. The smaller arm now picks up the sample, and then shuttles it to other stations. A probe measures the volume of the sample, and the camera takes photos of the tube. Next, a dispenser inserts a seal into the tube. The seal is activated by another station. To ensure everything is in order, the camera takes more photos of the sample before it is returned to the robot's stomach for temporary storage.As it travels around Mars, the robot will likely collect approximately three dozen samples. Samuels said that the robot will drive around with these tubes until it is ready to drop them off at a collective cache. These tubes will be stored in the cache until a future Mars sample returning mission retrieves them and takes them to Earth. She explained that the science team is searching for different types of rockssedimentary and igneous to be able bring back, as they will tell us different aspects about Mars. Scientists from many institutions will be able study the geology and history of Mars once the retrieval mission has returned.AdvertisementThis is done autonomously by the robot. Perseverance, like its sibling rovers on Mars, cannot be relied on humans to continuously pilot it around Mars. It takes 20 minutes for radio signals between the two planets to reach them. Perseverance is mostly a "set-it-and forget-it" type of science machine. Samuels said that it is totally hands-off from the moment the sample tube is removed from storage to the point when it is returned to storage. It is all autonomous.Although the drilling failed to go according to plan, it could have provided crucial clues about Martian geology. Stack Morgan and other NASA scientists had assumed that the rock was either a solid sedimentary (crystalized magnesium) or a basalt (crystalized iron). Based on the behavior of the rock when it was drilled, Stack Morgan and other NASA scientists now believe that basalt is more likely to crystallize at depth to create coarse grains. Stack Morgan says that the rock broke apart along these kinds of grain boundaries when we began to core it.Perseverance is drilling on a former lake bed. It could possibly provide signs of microbial activity if it can drill into sedimentary rockslayers of lakewater. However, scientists can date when magma became hard rock by studying basalt and other igneous rocks.Perseverance might have found something exciting. Stack Morgan says that the best case scenario was actually when we were able to core this rock. The next best scenario is when we may have discovered a series of rocks that could allow us to both explore the area's habitability and provide age constraints that will help us determine exactly when Jezero Crater became habitable.NASA has not yet announced a date for Perseverance's next move. However, chief engineer Louise Jandura stated in a blog post that Perseverance will leave the first borehole and continue to the next sampling site. The Ingenuity helicopter identified the location as likely to contain sedimentary rock, which we expect will be more compatible with our Earth-based testing experience.She continued, but the hardware did what she asked. The rock refused to cooperate. This reminds me once again of the nature exploration. No matter how well you plan, you can never be certain of a specific result.This story first appeared on wired.com
