A Phoenix has reappeared at the SETI Institute, this time in the form of NASA's next Mars lander, which has the involvement of Dr. John Marshall in the science team. NASA's Phoenix Mission is headed to Mars to look for
water, and carbon compounds that could signify life on Mars. Like
its namesake mythological bird, NASA's Phoenix Mission rises from remnants of
its predecessors. It will use many components of a spacecraft originally built
for a 2001 Mars lander mission, which was kept in careful storage after that
mission was cancelled.
This is the second "Phoenix" at the SETI Institute; the first
was Project
Phoenix which arose after the demise of NASA's High Resolution Microwave
Survey (HRMS) in 1992. HRMS had been designed to conduct a broad survey and a
targeted star search for evidence of sentient life (aka, signals from
technological civilizations) in the Milky Way Galaxy. The SETI Institute picked
up the pieces from HRMS, and with private philanthropy, funded a decade of
targeted star SETI research using major radio telescopes world-wide under the
banner of Project Phoenix.
Today, NASA's Phoenix
Mission is seeking evidence for microbial life on the nearby planet Mars,
SETI Institute is involved in this search, as well.
Dr. John Marshall is a research
scientist at the Carl Sagan Center (CSC) of the SETI Institute with a
particular interest; he studies dust. Don't think of him as the "dustman,"
rather, he's a geologist who works at the microscopic scale. He studies dust to
understand how water and wind have altered the surface of the tiny bits of rock
to learn about the geological history of materials here on Earth, and soon, on
Mars. Marshall is a co-investigator on NASA's
Phoenix Mars Mission, which is first scheduled to launch August 3. Phoenix is a "Scout" mission led by PI Peter Smith at the University of Arizona. Like other CSC scientists, Marshall frequently collaborates with scientists and
engineers at universities and NASA centers to conduct research onboard NASA
space missions.
The Phoenix lander will set down in icy soils near the permanent north polar ice cap of Mars
and explore the history of the water in the ice while monitoring polar climate.
Phoenix is NASA's first exploration of a potential modern habitat on Mars (in
search of carbon-bearing compounds) since the 1970s when NASA's two Viking
missions landed on Mars. The science payload for Phoenix includes instruments
built for the 2001 lander and improved versions of others flown on the lost Mars
Polar Lander in 1999. In particular, Dr. Marshall will be analyzing the
images from the microscope that is part of MECA,
the Microscopy, Electrochemistry and Conductivity Analyzer which will look at
dust in surface samples.
Dr.
Marshall received his training as a geologist at University College London in England, but has spent his professional career in the United States. Marshall's specialty is
sedimentology, and specifically the study of clastic particles – these are the
sand and dust grains that comprise volcanic eruptions, dust
storms, sand dunes, river sediments, beach sand, and so forth. These are
grains of dust the size of particles of flour—a few microns in diameter—to the
sand grains that you find at the seaside. For three decades, Marshall has investigated
the material from two perspectives –their appearance under the microscope, and
their electrostatic behavior. With the Phoenix Mission, he's taking his
microscope to Mars, seeking evidence of water and life near the polar ice cap.
What can we
learn from dust? If you ask Marshall, the answer is "plenty." Tiny
grains of dust and sand record their history as microscopic textures on their
surfaces. The effect of water in creating these surface textures can be detected.
The Phoenix mission will provide the first microscope images from Mars – soil
particles will be scooped up by a robotic arm, and examined to determine if
liquid water has played a role in the physical and chemical evolution of
materials at the landing site. Elucidating the role of liquid water on Mars
using microscopic clues can provide valuable information about ancient climates
on Mars, and the potential for life to have evolved there. Dr. Marshall is the
lead scientist for geological interpretation of the size, shape, and textural
characteristics of soil particles examined by the Phoenix mission microscope.
Marshall works on planetary protection as
well: when we send a spacecraft to Mars, how can we keep from
forward-contaminating the site with materials that actually originate from
Earth? The Phoenix Mission will be looking for evidence of water and life on
Mars, and Marshall and the other scientists on the team do not wish to discover
Earth-derived materials instead of Martian materials. Later this year, Marshall
and Dr. Rocco Mancinelli, a CSC microbiologist, will run a simulation at NASA Ames Research Center of the Phoenix landing using a one-half scale model from University of Michigan to test how materials might be abraded from the Phoenix spacecraft
during landing and deposited on nearby Martian soils. If carbon-compounds are
discovered on Mars, the team wants to be sure that they are Martian.
Among his
varied projects, he's also studied dust devils on Earth and Mars, and the
significant problems caused by dust clinging (actually sticking) to the
astronaut's space suits. During the Apollo days, moon walkers became coated
with lunar dust that clung tenaciously to their suits, boots and helmets,
penetrated the space suit joints, and was tracked back into the landers. In
preparing for the return to the Moon, and human travel to Mars, this remains a
significant challenge: how can astronauts and equipment be protected from the
clinging and penetrating dust? It's a work in progress.
Recently, I
asked Marshall about his career as a research scientist and how he'd taken this
pathway that is now leading to Mars. He said, "While space is a great
place to extend my research on the nature of particles and their interactions,
I'm fundamentally motivated to understand the basic nature of particulate
materials. I'm a scientist, and when all is said and done, I'd like to be distinguished
as the guy who did fundamental work on clastics, here on Earth and elsewhere,
including Mars. My scientific discoveries are most important to me. Rather than
being thought of as a Mars scientist who did something with samples of Martian
soil, I'd like to be respected for my research into particulate materials. For
me, space is simply a good place to do excellent science, and that's what
motivates me."
With more
than three decades of specialized research, Marshall looks forward to reading
the stories written in Martian dust in the near future when the microscopic
images are transmitted to Earth from the Phoenix lander. With Marshall, we'll
all learn more about water on Mars, and perhaps about life on that small red
world.
advertisement
