Search for Life on Mars
Evidence of Past Life on Mars
• The problem with Mars is not that it is too
far from the Sun, the main problem is that it
is too small to resist evaporation of
atmospheric gases.
• In the past, Mars may have had an
atmospheric like the Earth’s but 99% was
lost.
•About 3.5 billion years ago on
Mars, conditions would have
been favorable. At this time, life
was certainly producing fossils
on Earth.
• The main challenge is to see if
live arose briefly at some point in
the past.
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VIKING
LANDINGS
ON MARS
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Mass spectrometer
No long chains of atoms!
Life
No Life
Why was there no
evidence?
The Viking tests were inconclusive
because gases were produced only
briefly, and other instruments found no
traces of organic materials that would be
expected if life were present.
The accumulated peroxide in the soil could
have fooled the Viking experiments looking
for life. These results are more indicative of a
chemical reaction than the presence of life,
Delory said.
The planet-wide dust storms that periodically
cloak Mars in a mantle of red may be
generating a snow of corrosive chemicals,
including hydrogen peroxide (H2O2) , that
would be toxic to life
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Present Exploration of Mars
Nasa has launch a spacecraft on a nine-month
journey to Mars, where it will dig below the
surface for clues to the existence of past or
present life. If everything goes to plan,
Phoenix should arrive at Mars in late May
2008.
On the northern plains, water ice is thought
to lie just a few tens of centimetres below the
surface, within reach of the lander's 2.4m
(7.5ft) robotic arm. Scientists estimate the ice
content of the upper metre of soil in this
region could be as high as 50-70%.
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Phoenix will land in the northern polar regions of the planet
Mars, whose low temperatures and relatively high atmospheric
water vapor should provide better growing conditions for such
microbes than the more tropical region visited by Viking.
Its purpose is to look for and study the water ice that is
expected to be found there. The mission will launch in August of
2007, and land on Mars in May, 2008.
Phoenix lander, 2008
Phoenix mission will
land a robot in the
polar region of Mars in
May 2008.
On the northern
plains, water ice is
thought to lie just a few
tens of centimetres
below the surface. The
lander is capable of
digging a 0.5 meter
trench in the soil.
The craft has a mass spectrometer capable of detecting organic
volatiles, an optical microscope and an atomic force microscope.
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The solar-powered craft will deploy its robotic arm to dig down vertically through the
soil towards the icy crust.
The arm will deliver samples of soil to the lander's deck for analysis by a powerful suite
of instruments.
These will check the samples for water and organics, characterise the physical
properties of the soil, determine abundances of different minerals, and subject dust
grains to microscopic examination.
ExoMars rover planned for launch
in 2013
Can detect key molecules associated with life at a sensitivity
roughly a million times greater than previous instrumentation
Can detect amino acidsat concentrations as
low as a few parts per trillion.
Can distinguish "left-handed" and "right-handed”
amino acids.
http://www.astrobio.net/news/Archives.html
An Astrobiology Field Laboratory (AFL) is planned for
launch in 2016,
to help answer questions about life on Mars. Its primary mission is
to last for about one Martian year
objective would be to specifically looki for life and the signs of life.
http://en.wikipedia.org/wiki/Exploration_of_Neptune
Martian Meteorites
• Antarctic meteorite finds, due
to analysis of trapped gases.
• The meteorite in questions, ALH
84001 is shown (left). This
meteorite is 4 billion years old,
dating from a time when liquid
water was present, causing some
sedimentary deposits.
• purported ‘microfossils’ - minute
structures 1/100 the width of a
human hair.
Picture credit: NASA GSFC
• The main problem with these
structures is the size: about the size
of a virus on Earth, which cannot
survive without access to the DNA
of a bacterium.
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Dislodged from Mars 16 Ma years ago
Fell to Earth 13,000 years ago, time is determined from the exposure to
radioactive nuclei in space
Discovered Alan Hills ( Antarctica ice field) in 1984
10 years later scientists found it and indentified it as coming from mars
announcement in 1996 of possible microfossils inside a Martian
meteorite
The Moon
In the 19th century, many
astronomers were
convinced the Moon was
inhabited by intelligent
aliens. We now know that
this isn't true. The Moon
has no atmosphere, so
life couldn't survive there.
Even so, the Apollo
astronauts were held in
quarantine after their trips
to the Moon - just in case
they had picked up any
space bugs.
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Return to the Moon ---- United States, Russia, India, Japan and
China ---have all announced plans to send astronauts back to
the Moon around the year 2020
AST121,Fall 2005
Robert Zimmerman
University of Oregon
Sec
4
The End