JPL/NSTA Web Seminar:

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LIVE INTERACTIVE LEARNING _at_ YOUR DESKTOP
JPL/NSTA Web Seminar Are We Alone?
Thursday, February 22, 2007 700 p.m. to 800
p.m. Eastern time
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Exploring for Martian life Jack Farmer (Arizona
State University)
WHAT IS ASTROBIOLOGY? The field of science that
studies the origin, evolution, distribution
future of life in the Cosmos
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LETS BEGIN BY ASKINGWhat is life?What does
it require?What are lifes limits?
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Important to realize.
Most life on Earth is microbial!
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You are here!
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Survey Question

• What is life? How would you define it?
• (answer in the direct messaging window)

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DEFINING LIFE

• Order- The structures and subsystems of living
  systems are highly ordered.
• Self-replication (reproduction)- Organisms
  replicate themselves through various methods of
  asexual or sexual reproduction.
• Growth and development- Patterns of
  genetically-controlled development.

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DEFINING LIFE

• Response to the environment Otherwise known as
  ecology, organisms interact with and respond to
  their environment.
• Evolutionary adaptation Life adapts to
  environmental changes through mechanisms of
  Darwinian evolution.
• The concept of necessary versus sufficient
  conditions

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REQUIREMENTS FOR LIFE

• Liquid water
• Essential elements
• Energy sources

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WHY WATER?
HYDROGEN BONDS
SOLVENT PROPERTIES
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Bioessential elements
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ENERGY SOURCES
http//www.pmel.noaa.gov/vents/nemo/education/imag
es/
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Survey Question

• What are some examples of extreme environments
  for life on Earth?
• (answer using your direct messaging window)

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Some Environmental Extremes of Life
Temperature -20 to 121 oC Salinity 0 to gt30
pH 1.0 to 13.0 Activity of water (Aw) 1.0
- 0.7 Oxygen aerobic to anaerobic Redox
Oxidizing to reducing
The activity coefficient for water is a measure
of its availability to participate in chemical
reactions. 1.0 fully available 0.0
unavailable.
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Multiple Choice Question
Which of the following environments on Earth have
been shown to be devoid of life?
A Hot springs on the deep ocean floor
B Highly saline lakes and seas
C Dry desert soils
D Acid mine drainages
E None of the above
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Fossilized cyanobacteria
Life at High Temperatures
Living cyanobacteria
Borchers Spring, Yellowstone
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Life at Low Temperatures
Microbes preserved in ice
Subglacial Lakes, Antarctica
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Life in boiling acidic mud (pH 2), Yellowstone
National Park
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Tufa Towers
Mono Lake, CA
Alkaline Saline Lakes (pH 10)
Fossil stromatolite
Fossilized bacteria
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Death Valley Playa
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Are such environments found on Mars?
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Multiple Choice Question

• Where should we explore for ancient (fossil) life
  on Mars?

A Upper few cms of surface soils
B Igneous rocks exposed at the surface
C Ancient lake deposits
D Ancient hot spring deposits
E C and D
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Opportunity Rover at Meridiani
Sulfate-rich evaporites
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Interdune Lake Sediments, Death Valley
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Phoenix Mission - 2007 The Phoenix (Mars Scout)
mission, which will launch in 2007, includes an
in-situ organic chemistry lab that will analyze
frozen soils and ices at a polar landing site.
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Survey Question

• What kinds of places should we explore for extant
  life on Mars?
• (answer using your direct messaging window)

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Challenges of deep subsurface robotic drilling
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Malin and Edgett (2000)
Seep-carved channels, Newton Crater
(Malin and Edgett, 2001)
Fluid seeps suggest recent water activityBut the
source of water remains uncertain.
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Approaches to Life Detection

• Nucleic acid probes Short strands of DNA, or RNA
  are used to selectively bind to complimentary DNA
  strands and proteins in samples.
• Often used in conjunction with a reporter
  molecule, such as a visible or flourescent marker
  compound that lights up under UV light.

Shavlik Page (2003)
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Biomolecules Detected Using Flourescence Probes
on a Microarray
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Survey Question

• What are some limitations of current approaches
  to extant life detection on Mars?
• (answer using your direct messaging window

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Conclusions

• The search for Martian life involves two
  distinctly different paths Looking for extant
  life and looking for fossil biosignatures.
• Life is found over a much broader range of
  environmental extremes than once believed,
  including extremes of temperature, pH, salinity,
  water and oxygen availability.
• This fact opens up exploration for life elsewhere
  in the Solar System to an equally broad range of
  surface and subsurface environments.

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National Science Teachers Association Gerry
Wheeler, Executive Director Frank Owens,
Associate Executive Director Conferences and
Programs Al Byers, Assistant Executive Director
e-Learning
NSTA Web Seminars Flavio Mendez, Program
Manager Jeff Layman, Technical Coordinator Susan
Hurstcalderone, Volunteer Chat Moderator
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