The Perseverance rover and its team of scientists back on Earth have been working diligently to explore the crater’s floor ever since it touched down at Jezero crater on Mars in February. The crater was once home to an old lake.
The Mars 2020 mission and perseverance are searching for traces of past life on Mars and assembling a returnable cache of samples for eventual examinations on Earth.
On Sunday, October 10, at the Geological Society of America’s Connects 2021 annual meeting in Portland, Oregon, Katie Stack Morgan, a research scientist at NASA’s Jet Propulsion Laboratory (JPL) and the Mars 2020 Deputy Project Scientist, will give an update on preliminary findings from the rover mission to Mars 2020.
The scientific team has been examining the rocks on the crater floor with Perseverance’s high-tech suite of on-board instruments. These rocks have currently been classified as igneous rocks and are most likely the remains of a volcanic lava flow.
“The idea that this could be a volcanic rock was really appealing to us from a sample return perspective because igneous rocks are great for getting accurate age dates. Jezero was one of the few ancient crater lake sites on Mars that seemed to have both incredible sedimentary deposits as well as volcanic deposits that could help us construct the geologic time scale of Mars,” said Stack Morgan.
However, the capacity to directly date the age of the rocks in labs on Earth will provide the first conclusive insight into the window of time that Mars may have been a livable planet. The lake system and rivers that flowed into Jezero crater were probably active around 3.8-3.6 billion years ago.
The scientists found that the crater floor appears to be formed of coarser-grained igneous minerals, and there are also a range of salts in the rocks, using Perseverance’s abrasion tool, which scratches the top surface of the rock to reveal the rock and its textures.
The crater bottom appears to have undergone extensive weathering and alteration as a result of water, indicating that the rocks were exposed to water for a considerable amount of time.
The rocks of the crater floor were not originally envisioned as the prime astrobiology target of the mission, but Mars always surprises us when we look up close. We are excited to find that even these rocks have experienced sustained interaction with water and could have been habitable for ancient martian microbes.
Katie Stack Morgan
After examining the crater floor’s properties with its on-board instruments, Perseverance’s next task was to use its drill feature to gather a rock sample. But when Perseverance finished its initial drilling, the core sample tube was empty.
“We spent a couple of days looking around the rover thinking that the core might have fallen out of the bit. Then we looked back down the drill hole thinking it might never have made it out of the hole. All these searches turned up empty. In the end we concluded that the core was pulverized during drilling,” said Stack Morgan.
The vibrations and force from the Perseverance drill likely crushed the sample because the rock had become so changed and weakened through contact with water.
After that, researchers focused on a different rock that seemed to be more resistant to weathering, and Perseverance was successful in obtaining two core samples as the initial part of its sample collection.
The samples from Perseverance will be transported to Earth in the early 2030s as part of a multi-spacecraft handoff that is now under development. The rocks will next be dated and examined by scientists in labs on Earth to check for any potential indications of prehistoric Martian life.
“The rocks of the crater floor were not originally envisioned as the prime astrobiology target of the mission, but Mars always surprises us when we look up close. We are excited to find that even these rocks have experienced sustained interaction with water and could have been habitable for ancient martian microbes,” said Stack Morgan.
