[meteorite-list] Mars Study Yields Clues to Possible Cradle of Life
From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 19 Oct 2017 16:40:15 -0700 (PDT)
Mars Study Yields Clues to Possible Cradle of Life
Jet Propulsion Laboratory
October 6, 2017
* A long-gone sea on southern Mars once held nearly 10 times as much water
as all of North America's Great Lakes combined, a recent report estimates.
* The report interprets data from NASA's Mars Reconnaissance Orbiter as
evidence that hot springs pumped mineral-laden water directly into this
ancient Martian sea.
* Undersea hydrothermal conditions on Mars may have existed about 3.7
billion years ago; undersea hydrothermal conditions on Earth at about
that same time are a strong candidate for where and when life on Earth
* The report adds an important type of wet ancient Martian environment
to the diversity indicated by previous findings of evidence for rivers,
lakes, deltas, seas, groundwater and hot springs.
The discovery of evidence for ancient sea-floor hydrothermal deposits
on Mars identifies an area on the planet that may offer clues about the
origin of life on Earth.
A recent international report examines observations by NASA's Mars Reconnaissance
Orbiter (MRO) of massive deposits in a basin on southern Mars. The authors
interpret the data as evidence that these deposits were formed by heated
water from a volcanically active part of the planet's crust entering the
bottom of a large sea long ago.
"Even if we never find evidence that there's been life on Mars, this site
can tell us about the type of environment where life may have begun on
Earth," said Paul Niles of NASA's Johnson Space Center, Houston. "Volcanic
activity combined with standing water provided conditions that were likely
similar to conditions that existed on Earth at about the same time --
when early life was evolving here."
Mars today has neither standing water nor volcanic activity. Researchers
estimate an age of about 3.7 billion years for the Martian deposits attributed
to seafloor hydrothermal activity. Undersea hydrothermal conditions on
Earth at about that same time are a strong candidate for where and when
life on Earth began. Earth still has such conditions, where many forms
of life thrive on chemical energy extracted from rocks, without sunlight.
But due to Earth's active crust, our planet holds little direct geological
evidence preserved from the time when life began. The possibility of undersea
hydrothermal activity inside icy moons such as Europa at Jupiter and Enceladus
at Saturn feeds interest in them as destinations in the quest to find
Observations by MRO's Compact Reconnaissance Spectrometer for Mars (CRISM)
provided the data for identifying minerals in massive deposits within
Mars' Eridania basin, which lies in a region with some of the Red Planet's
most ancient exposed crust.
"This site gives us a compelling story for a deep, long-lived sea and
a deep-sea hydrothermal environment," Niles said. "It is evocative of
the deep-sea hydrothermal environments on Earth, similar to environments
where life might be found on other worlds -- life that doesn't need a
nice atmosphere or temperate surface, but just rocks, heat and water."
Niles co-authored the recent report in the journal Nature Communications
with lead author Joseph Michalski, who began the analysis while at the
Natural History Museum, London, andco-authors at the Planetary Science
Institute in Tucson, Arizona, and the Natural History Museum.
The researchers estimate the ancient Eridania sea held about 50,000 cubic
miles (210,000 cubic kilometers) of water. That is as much as all other
lakes and seas on ancient Mars combined and about nine times more than
the combined volume of all of North America's Great Lakes. The mix of
minerals identified from the spectrometer data, including serpentine,
talc and carbonate, and the shape and texture of the thick bedrock layers,
led to identifying possible seafloor hydrothermal deposits. The area has
lava flows that post-date the disappearance of the sea. The researchers
cite these as evidence that this is an area of Mars' crust with a volcanic
susceptibility that also could have produced effects earlier, when the
sea was present.
The new work adds to the diversity of types of wet environments for which
evidence exists on Mars, including rivers, lakes, deltas, seas, hot springs,
groundwater, and volcanic eruptions beneath ice.
"Ancient, deep-water hydrothermal deposits in Eridania basin represent
a new category of astrobiological target on Mars," the report states.
It also says, "Eridania seafloor deposits are not only of interest for
Mars exploration, they represent a window into early Earth." That is because
the earliest evidence of life on Earth comes from seafloor deposits of
similar origin and age, but the geological record of those early-Earth
environments is poorly preserved.
The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland,
built and operates CRISM, one of six instruments with which MRO has been
examining Mars since 2006. NASA's Jet Propulsion Laboratory, a division
of Caltech in Pasadena, California, manages the project for the NASA Science
Mission Directorate in Washington. Lockheed Martin Space Systems of Denver
built the orbiter and supports its operations. For more about MRO, visit:
News Media Contact
Jet Propulsion Laboratory, Pasadena, Calif.
guy.webster at jpl.nasa.gov
Johnson Space Center, Houston
Norma.j.knotts at nasa.gov
Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington
202-358-1077 / 202-358-1726
laura.l.cantillo at nasa.gov / dwayne.c.brown at nasa.gov
Received on Thu 19 Oct 2017 07:40:15 PM PDT