July 21 (UPI) -- For the first time in history, a NASA rover is preparing to scoop up, seal and cache Martian rock samples for a future return trip to Earth.
In 2008, a scientific panel organized by NASA determined a sample return would be "the single mission that would make the most progress" in understanding Martian geology and possible biology.
More than a decade later, NASA's most ambitious Martian rover mission is preparing to make good on the panel's recommendation.
"We are ready to sample," Jennifer Trosper, Perseverance project manager, said during a live press briefing and presentation on Wednesday. "We expect to get our first sample within the first couple weeks of August."
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Over the last few weeks, NASA's Mars rover, Perseverance, has been trekking across Jezero Crater from the rover's landing site to points of scientific interest within the ancient lakebed.
Jezero is positioned near the western edge of Isidis Planitia, a massive basin north of the Martian equator.
Millions of years ago, the crater was home to an expansive lake bed and river delta. Today, it hosts a unique mix of minerals like clays, carbonates and hydrated silica -- sediments and rocks that might host signs of ancient life.
During the initial leg of Perseverance's road trip, the rover has been using its cameras and instruments to find and analyze interesting rocks and regolith -- candidates for sample collection.
Ideally, sample rocks collected by Perseverance will offer insights into the Red Planet's geologic history and possibly yield signatures of ancient microbial activity.
Perseverance's first sample will be extracted from an area that team members have dubbed the "Cratered Floor Fractured Rough" geologic unit.
"For the first sample, what we're really looking for is a rock that is prototypical of the Cratered Floor Fractured Rough geologic unit," said Vivian Sun, Perseverance science campaign co-lead. "We want this sample to summarize and record the history of this entire unit."
Over the past few weeks, Perseverance hasn't witnessed the plethora of finely layered rocks that are omnipresent in Gale Crater, home to NASA's Curiosity rover. This was expected.
However, during its road trip south to its first sample locale, the rover stopped to check out a couple of the crater floor's oldest, accessible geologic units, including a pair of units named "Seitah" -- Navajo for "amidst the sand."
There, scientists spotted a layered rock with patterns suggesting the ancient lakebed periodically dried and refilled over millions of years.
"These layered rocks have been kind of hard to come by, and we all were very happily surprised to see that there are layers in the rocks within that unit," Sun said.
Each layer represents unique time periods from region's ancient past.
"This is very important, it means that we will have multiple time periods from which we can learn about conditions on Mars and multiple time periods from which we can look for signs of ancient life," said Ken Farley, a Caltech researcher and Perseverance project scientist.
Farley said the most straight forward interpretation of these layered rocks is that they were formed by impacted sediment -- sediment layers deposited on the ancient lakebed over many millions of years.
"This is exactly the kind of rock that we're most interested in investigating and looking for potential biosignatures of ancient microbes," he said.
In the coming weeks, Perseverance will begin surveying the Cratered Floor Fractured Rough geologic unit, using its many cameras and instruments to document the surrounding environs and identify an ideal sampling location.
Once Perseverance finds a suitable sampling spot, the rover's special sample-handling arm will retrieve a sample tube, heat it and insert it into a coring bit. The tube and bit will then be affixed to the rotary-percussive drill on the rover's robotic arm.
After scraping away the top layer of dust and regolith, to expose unweathered rocks, Perseverance's drill will fire away and capture a chalk-sized rock sample, which will become sealed within the sample tube.
At a later date, the rover will cache its stored samples at a yet-to-be-determined rendezvous site. Eventually, those samples will be retrieved by a separate spacecraft and returned to Earth.
"Not every sample Perseverance is collecting will be done in the quest for ancient life, and we don't expect this first sample to provide definitive proof one way or the other," Farley said of the rover's first sample.
"While the rocks located in this geologic unit are not great time capsules for organics, we believe they have been around since the formation of Jezero Crater and incredibly valuable to fill gaps in our geologic understanding of this region -- things we'll desperately need to know if we find life once existed on Mars," Farley said.
