The first data from are in, revealing clues about the possibility of past life on the Red Planet. And two UNLV geoscientists are in on the action as part of the NASA’s Mars 2020 science team and as co-authors on three new papers detailing the findings.
UNLV planetary rock and meteorite expert Arya Udry and Libby Hausrath, an aqueous geochemist and astrobiologist who investigates interactions between water and minerals, are among researchers who’re studying rock and soil data gleaned from Perseverance’s rock-vaporizing laser, ground-penetrating radar, and X-ray technology.
Percy, as the rover is nicknamed, launched from Cape Canaveral, Fla. in July 2020, and arrived in February 2021 at Jezero Crater — a 28-mile-wide former lakebed selected for its potential to help scientists understand the story of Mars’ wet past. The yearslong mission seeks to determine whether Mars ever supported life, understand the processes and history of Mars’ climate, understand the origin and evolution of Mars as a geologic system, and prepare for human exploration.
Papers published in the journals Science and Science Advances address major questions including:
Down By The River
Scientists got a surprise when Perseverance began examining rocks on the floor of Jezero Crater last spring: Because the crater held a lake billions of years ago, they had expected to find sedimentary rock, which would have formed when sand and mud settled in a once-watery environment. Instead, they discovered the floor was made of two types of igneous rock – one that formed deep underground from magma, the other from volcanic activity at the surface.
Igneous rocks are excellent timekeepers: Crystals within them record details about the precise moment they formed. That’s great news for scientists, who’ll use the rocks to pinpoint when Jezero’s lake formed as well as the timeline of Mars’ evolution to the very dry and cold climate conditions of today.
However, because of how it forms, igneous rock isn’t great at preserving potential signs of ancient microscopic life. Conversely, sedimentary rock — which often forms in watery environments conducive to life — is, so the rover has been drilling and collecting samples from Jezero’s sediment-rich river delta.
Hausrath is a member of the Mars Sample Return team that will determine which specimens the rover will bring back to Earth in 2033 for inspection by powerful lab equipment too large to shoot off to Mars.
“The fine-scale analyses that will be possible on Earth will allow questions to be answered about Mars that we can’t answer with rovers on the surface,” Hausrath said. “Most excitingly, we could potentially find evidence of ancient life.”
Rock of Ages
Meteorite impacts? Volcanic eruptions? Sedimentary processes? For years, scientists have theorized how Séítah, a large rock formation filled with olivine — a mineral commonly associated with Hawaii’s green beaches — appeared on the Red Planet and covered such a large surface area.
Perseverance appears to have solved the longstanding mystery. With the help of the rover’s abrasion and X-ray instruments, the NASA team was able to study the chemistry and texture of an exposed patch of rock. They determined the olivine’s grain size was much larger than would be expected for olivine that formed in rapidly cooling lava at the planet’s surface. Rather, they believe the olivine formed deep underground from very slowly cooling magma — molten rock — before being exposed over time by erosion.
Udry’s role on the NASA team is to help distinguish igneous from sedimentary rocks, understand how these igneous rocks form, and analyze their links to Martian meteorites that scientists around the world have studied over the decades.
“The mineralogy and chemistry resemble that of Martian meteorites we’ve found on Earth, although their chemistry and mineralogy is very slightly different,” Udry said. “However, meteorites, the only samples that we currently possess from Mars, do not have any ground truth context. Being able to analyze and date these Martian rocks in Earth-based laboratories, while having for the very first time field context from Martian rocks, will allow us to better ascertain the magmatic evolution of the Red planet and, ultimately, help us compare Mars to Earth’s interior.”
Let There Be Light
Both Hausrath and Udry contributed to a NASA team study that used state-of-the-art rover tools to establish that igneous rocks, which are formed by cooling magma, cover the crater floor.
Perseverance used near-infrared light — the first instrument on Mars with that capability — to find that water altered minerals in the crater floor rocks. The alterations aren’t pervasive, but Udry and Hausrath say the finding bolsters scientists’ theory about life-sustaining water once flowing on the planet.
The NASA team also used a laser on the SuperCam instrument which can zap a target as small as a pencil tip from 20 feet away, to fire at 1,450 points and examined the resulting plasma using a visible-light spectrometer to determine the rocks’ chemical composition.
What’s Next
As data continue to pour in, Udry and Hausrath are leading additional research into the rover data and working alongside UNLV students and colleagues to analyze it.
Soil on Mars forms a crust and it breaks as the rover drives over. Hausrath is exploring the soil chemistry to figure out why this happens and learn more about the ways salts, soil, water, and the atmosphere interact.
Udry is looking in greater detail at the Máaz (meaning ‘Mars’ in the Navajo language) — the first sets of rocks analyzed in the first year of the mission — as well as lava flows to determine the diversity of magmatic processes including mineralogy, chemistry, and how rocks melt.
“It’s an amazing planet,” Hausrath said, “and this up-close view of it is really exciting.”
---
Information from a was included in this article.
