[meteorite-list] Dry Signs of Life

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon Mar 21 13:24:56 2005
Message-ID: <200503141919.j2EJJVb11887_at_zagami.jpl.nasa.gov>

http://www.astrobio.net/news/article1484.htm

Dry Signs of Life
Astrobiology Magazine
March 13, 2005

Summary: A unique rover-based life detection system developed by
Carnegie Mellon University scientists has found signs of life in Chile's
Atacama Desert. This marks the first time a rover-based automated
technology has been used to identify life in this harsh region, which
serves as a test bed for technology that could be deployed in future
Mars missions.
  

Dry Signs of Life

based on Carnegie-Mellon report

A unique rover-based life detection system developed by Carnegie Mellon
University scientists has found signs of life in Chile's Atacama Desert,
according to results being presented at the 36th Lunar and Planetary
Science Conference March 14-18 in Houston. This marks the first time a
rover-based automated technology has been used to identify life in this
harsh region, which serves as a test bed for technology that could be
deployed in future Mars missions.

"Our life detection system worked very well, and something like it
ultimately may enable robots to look for life on Mars," said Alan
Waggoner, Atacama team member and director of the Molecular Biosensor
and Imaging Center at the university's Mellon College of Science.

The "Life in the Atacama" 2004 field season - from August to mid-October
- was the second phase of a three-year program whose goal is to
understand how life can be detected by a rover that is being controlled
by a remote science team. The project is part of NASA's Astrobiology
Science and Technology Program for Exploring Planets, or ASTEP, which
concentrates on pushing the limits of technology in harsh environments.
David Wettergreen, associate research professor in Carnegie Mellon's
Robotics Institute, leads rover development and field investigation
aspects of the project. Nathalie Cabrol, a planetary scientist at NASA's
Ames Research Center and the SETI Institute, leads the science
investigation.

Life is barely discernable over most areas of the Atacama, but the
rover's instruments were able to detect lichens and bacterial colonies
in two areas: a coastal region with a more humid climate and an
interior, very arid region less hospitable to life.

"We saw very clear signals from chlorophyll, DNA and protein. And we
were able to visually identify biological materials from a standard
image captured by the rover. Taken together, these four pieces of
evidence are strong indicators of life," said Waggoner. "Now, our
findings are being confirmed in the lab. Samples collected in the
Atacama were examined, and scientists found that they contained life.
The lichens and bacteria in the samples are growing and awaiting analysis."

Waggoner and his colleagues have designed a life detection system
equipped to detect fluorescence signals from sparse life forms,
including those that are mere millimeters in size. Their fluorescence
imager, which is located underneath the rover, detects signals from
chlorophyll-based life, such as cyanobacteria in lichens, and
fluorescent signals from a set of dyes designed to light up only when
they bind to one of the following - nucleic acid, protein, lipid or
carbohydrate - all molecules of life.

"We don't know of other remote methods capable both of detecting low
levels of micro-organisms and visualizing high levels incorporated as
biofilms or colonies," said Gregory Fisher, project imaging scientist.

"Our fluorescent imager is the first such system to work in the daylight
while in the shade of the rover. The rover uses solar energy to operate
so it needs to travel during daylight hours. Many times, the images we
capture may only reveal a faint signal. Any sunlight that leaks in to
the camera of a conventional fluorescence imager would obscure the
signal," said Waggoner.

"To avoid this problem, we designed our system to excite dyes with high
intensity flashes of light. The camera only opens during those flashes,
so we are able to capture a strong fluorescence signal during daytime
exploration," said Shmuel Weinstein, project manager.

During the mission, a remote science team located in Pittsburgh
instructed the rover's operations. A ground truth team at the site
collected samples studied by the rover to bring back for further
examination in the lab. On a typical day in the field, the rover woke up
and followed a path designated the previous day by the remote operations
science team. The rover followed a transect and stopped occasionally to
perform detailed surface inspection, effectively creating a "macroscopic
quilt" of geologic and biological data in selected 10 by 10 centimeter
panels. After the rover departed a region, the ground truth science team
collected samples the rover had examined.

"Based on the rover findings in the field and our tests in the
laboratory, there is not one example of the rover giving a false
positive," said Edwin Minkley, director of the Center for Biotechnology
and Environmental Processes in the Department of Biological Sciences.
"Every sample we tested had bacteria in it."

Minkley is conducting analyses to determine the genetic characteristics
of the recovered bacteria to identify the different microbial species
present in the samples. He also is testing the bacteria's sensitivity to
ultraviolet (UV) radiation. One hypothesis is that the bacteria may have
greater UV resistance because they are exposed to extreme UV radiation
in the desert environment. This characterization also may explain why
such a high proportion of the bacteria from the most arid site are
pigmented - red, yellow or pink - as they grow in the laboratory,
according to Minkley.

The first phase of the ASTEP project began in 2003 when a solar-powered
robot named Hyperion, also developed at Carnegie Mellon, was taken to
the Atacama as a research test bed. Scientists conducted experiments
with Hyperion to determine the optimum design, software and
instrumentation for a robot that would be used in more extensive
experiments conducted in 2004 and in 2005. Zo?, a brand new robot, was
developed in response to what was learned in 2003. In the final year of
the project, plans call for Zo?, equipped with a full array of
scientific instruments, to operate autonomously as it travels 50
kilometers over a two-month period.

------------------------------------------------------------------------

The science team, led by Cabrol, is made up of geologists and biologists
who study both Earth and Mars at institutions including NASA's Ames
Research Center and Johnson Space Center, SETI Institute, Jet Propulsion
Laboratory, the University of Tennessee, Carnegie Mellon, Universidad
Catolica del Norte (Chile), the University of Arizona, the University of
California, Los Angeles, the British Antarctic Survey, and the
International Research School of Planetary Sciences (Pescara, Italy).
Received on Mon 14 Mar 2005 02:19:30 PM PST