What has the Perseverance discovered on Mars after two years?
Perseverance's arm-mounted percussive drill scraped the dust and top few millimeters off a rocky outcrop in a 5-centimeter circle. The rover's camera caught fractured pieces stuck together from above. Crystals interlocked. Scientists who spent years planning for the expedition were surprised by such textures.
Then the scientists observed the rover's two spectrometers disclose the meshed textures' chemistry via video conference. Rochette, a volcanic rock, was shaped and chemically composed. It didn't have lake bed clay and silt.
On February 18, 2021, Percy and Ingenuity landed on the Jezero crater. Percy, the most complicated Martian surface explorer, builds on the work of the 2012 Curiosity rover, the twin Spirit and Opportunity rovers, the Sojourner rover, and other lenders.
Perseverance's goal is different. Percy searches for clues of previous life, whereas the other rovers study Martian geology and ecology.
The Mars 2020 mission chose Jezero because it seems from orbit to be a former lake habitat where microorganisms may have flourished. Its vast delta would likely preserve any indications of them.
The rover is drilling, scraping, and gathering Red Planet samples to search for ancient life with its seven pieces of research equipment. It collects samples for Earth.
Since landing, “we've been able to start piecing together the tale of what has transpired in Jezero, and it's complex,” says Briony Horgan, a planetary scientist at Purdue University in West Lafayette, Ind., who helps plan Percy's daily and long-term operations.
Volcanic rock is one of the rover's surprises. Hundreds of experts studying Perseverance's data now know how the crater has changed.
Lava, a lake that may have lasted tens of thousands of years, rivers that formed a mud-and-sand delta, and massive floods that carried boulders from remote places have all occurred in this region.
Jezero's history was more dramatic than scientists expected. Such instability has hindered the hunt for sedimentary rocks and revealed new alcoves where ancient life might have taken root.
Horgan says perseverance has found carbon-bearing elements, the source of life on Earth, in every sample it has rubbed. “It's everywhere.” The rover still has more to investigate.
Persistence uncovers surprising rocks.
Jezero, a shallow 45-kilometer impact crater, is north of the planet's equator. The crater developed between 3.7 billion and 4.1 billion years ago, during the solar system's first billion years. It's in Isidis, an older and wider impact basin. An old riverbed turns into a fan-shaped delta on Jezero's western curve.
Astrobiologist Ken Williford of Seattle's Blue Marble Space Institute of Science states that the delta "is like this flashing beacon brilliantly seen from orbit that tells us there was a standing body of water here."
Two kilometers from the delta, Perseverance crashed on the crater bottom. Experts expected compacted dirt and sand near Lake Jezero's base.
According to NASA's Jet Propulsion Laboratory's planetary geologist Kathryn Stack Morgan, the terrain appeared different than predicted. Stack Morgan is Perseverance's deputy project scientist.
After landing, the Mars 2020 mission crew gently and carefully evaluated the rover's movements and equipment.
Researchers on Earth discovered what they found during the first major scientific digging near the landing site. Stack Morgan called the rock "a typical igneous volcanic rock texture." It resembled volcanic lava.
Many other boulders on the crater bottom showed igneous structure during the following six months. Rochette had olivine crystals everywhere.
Abigail Allwood of the Jet Propulsion Lab explains, “The crystal fabric was cooled from a melt, not transferred grains.” PIXL, the rover's X-ray beam instrument, is under her command.
Mission scientists now assume the crater bottom is packed with igneous rocks from two events after the crater was produced, hence more recently than the 3.7 billion to 4.1 billion years ago time period.
Magma from deep inside the globe surged towards the surface, cooled and hardened, and was subsequently exposed by erosion. The other had lesser lava flows.
