Rocks on floor of Jezero Crater, Mars, show signs of sustained
interactions with water

Date:
October 8, 2021
Source:
Geological Society of America
Summary:
Since the Perseverance rover landed in Jezero crater on Mars in
February, the rover and its team of scientists back on Earth have
been hard at work exploring the floor of the crater that once held
an ancient lake.

Perseverance and the Mars 2020 mission are looking for signs of
ancient life on Mars and preparing a returnable cache of samples
for later analyses on Earth.



FULL STORY ========================================================================== Since the Perseverance rover landed in Jezero crater on Mars in February,
the rover and its team of scientists back on Earth have been hard
at work exploring the floor of the crater that once held an ancient
lake. Perseverance and the Mars 2020 mission are looking for signs of
ancient life on Mars and preparing a returnable cache of samples for
later analyses on Earth.


========================================================================== Katie Stack Morgan is the Mars 2020 Deputy Project Scientist and a
research scientist at NASA's Jet Propulsion Laboratory (JPL), and will
be providing an update on early results on the Mars 2020 rover mission
on Sunday, 10 Oct., at the Geological Society of America's Connects 2021
annual meeting in Portland, Oregon.

With Perseverance's high-tech suite of on-board instruments, the
scientific team has been analyzing the rocks of the crater floor,
interpreted for now as igneous rocks, presumably 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.

The lake system and rivers that drained into Jezero crater were likely
active around 3.8-3.6 billion years ago, but the ability to directly date
the age of the rocks in laboratories on Earth will provide the first
definitive insight into the window of time that Mars may have been a
habitable planet.

Using Perseverance's abrasion tool -- which scratches the top surface of
the rock to reveal the rock and its textures -- the team discovered that
the crater floor seems to be composed of coarser-grained igneous minerals,
and there are also a variety of salts in the rocks. Observations suggest
that water caused extensive weathering and alteration of the crater floor, meaning that the rocks were subjected to water for a significant duration
of time.

After using its on-board tools to analyze characteristics of the crater
floor, the next phase was for Perseverance to collect a rock sample
using its drill feature. However, after Perseverance completed its first attempt at drilling, the core sample tube came up 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 rock likely became so altered and weakened from interactions with
water that the vibrations and strength from the Perseverance drill
pulverized the sample.

Scientists then targeted another rock that appeared more resistant to weathering, and Perseverance was able to successfully collect two core
samples -- the first in its sample collection. Perseverance's cache of
samples will be part of a multi-spacecraft handoff, still in development,
that will hopefully be returned to Earth in the early 2030s. From there, scientists in laboratories on Earth will date and analyze the rocks to
see if there might be any signs of ancient 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.

========================================================================== Story Source: Materials provided by Geological_Society_of_America. Note: Content may be edited for style and length.


==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2021/10/211008160510.htm

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