The surprising reason a Mars rover just started dropping samples

Look carefully at this new image taken just days ago on Mars, and you might mistake that object sitting on the dusty barren surface as… wait, is that a lightsaber?

Sorry, Star Wars fans. What you see is a sealed NASA tube containing samples collected by the Perseverance rover, a car-size lab on six wheels that has been rumbling over the Martian terrain for nearly two years. The U.S. space agency said the vehicle "deposited" the tube — or what we normal folks would describe as "just left it sitting there" — on Dec. 21. Another was dropped similarly two days later.

The rover hasn't gotten clumsy. The samples are the first of many that will be set down on the ground on purpose.

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Over the course of its mission, Perseverance has been taking sample pairs from each rock so that it has a backup supply. So far it has filled 18 of the 38 sample tubes kept within its belly. The plan is for the rover to deliver the samples to a robotic lander equipped with a rocket at a later time to bring them back to study.

The "depot" (i.e., that seemingly arbitrary spot on the ground) will be for the backup in case Perseverance can't make the transfer. Plan B would involve recovery drones picking those samples up and flying them to a lander in about nine years.

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But the startling image of a Martian return sample left behind has drawn concern from the general public: Is it going to be safe just sitting there like that?, people have wondered. After all, it was a thick layer of Martian dust that took out the InSight lander, caking its solar panels so it could no longer soak up rays for power. NASA announced the lander's death and the end of that mission just a few days ago.

To be sure, the Red Planet has become notorious for its dust devils, particularly at Jezero crater, the landing site of Perseverance. Mars does indeed get windy, but it's not like on Earth, say NASA jet propulsion laboratory scientists based at Caltech. The gusts can blow fast, but not very strong, so they're unable to lift and carry objects well.

"Not only do we expect the sample tubes not to be covered up, but I’m also very carefully documenting exactly where I put them down," said NASA through its anthropomorphized Perseverance account on Twitter. "So going back to them again later shouldn’t be an issue."

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NASA sent Perseverance to the crater, because it's a place where planetary scientists think microscopic organisms — aka, life — might have existed long ago. The region is thought to be a dried delta, where water once emptied from a river into a lake. The remaining rocks may contain relics or clues about ancient life forms, if there were any.

This mission is the first attempt to bring back Martian dust and dirt. With the help of the European Space Agency, NASA wants to send spaceships to pick up the samples. If all goes to plan, they'll be back on Earth in the early 2030s.