Life on Mars?
17 February 2015
Are we alone?
• Life arose quickly on Earth, around 4 billion
years ago
• Star formation makes planets, too: they
should be common
• Impacts can frustrate life, but it recovers
• Extreme life forms ‘like it hot’ and may have
arisen first on ocean bottoms
• Moons also have heat sources
Urey-Miller Experiment
The Drake Equation
From Saturday’s Wall Street Journal:
The Drake equation applied to finding a girlfriend in Philadelphia:
Also, in this case, probabilities are too uncertain!
Get empirical evidence.
MSL Objectives
Mars Science Laboratory is a rover that will
assess whether Mars ever was, or is still
today, an environment able to support
microbial life. In other words, its mission is
to determine the planet's "habitability."
NASA's Mars Curiosity rover has
measured a tenfold spike in methane, an
organic chemical, in the atmosphere
around it and detected other organic
molecules in a rock-powder sample
collected by the robotic laboratory's drill.
"This temporary increase in methane -sharply up and then back down -- tells us
there must be some relatively localized
source," said Sushil Atreya of the
University of Michigan, Ann Arbor, a
member of the Curiosity rover science
team. "There are many possible sources,
biological or non-biological, such as
interaction of water and rock."
Curiosity also detected different Martian
organic chemicals in powder drilled from a
rock dubbed Cumberland, the first
definitive detection of organics in surface
materials of Mars. These Martian organics
could either have formed on Mars or been
delivered to Mars by meteorites.
Organic molecules, which contain carbon
and usually hydrogen, are chemical
building blocks of life, although they can
exist without the presence of life.
Curiosity's findings from analyzing samples
of atmosphere and rock powder do not
reveal whether Mars has ever harbored
living microbes, but the findings do shed
light on a chemically active modern Mars
and on favorable conditions for life on
ancient Mars.
Cumberland' Target Drilled by Curiosity
NASA's Mars rover Curiosity drilled into
this rock target, "Cumberland," during the
279th Martian day, or sol, of the rover's
work on Mars (May 19, 2013) and collected
a powdered sample of material from the
rock's interior.
Summary: Life
• Life is a chemical process that includes
metabolism, growth and reproduction.
• All life on earth evolves
• The 3 requirements for life: biogenic elements
(SPONCH), water and energy
• Earth life is based on carbon and requires
liquid water
• The range of distance where a planet can have
liquid water on its surface is the ‘habitable
zone’
More Summary: Life
• Large impacts can destroy life forms or even
sterilize the planet. Jupiter protects Earth from
asteroid impacts. Life changes the planet
• All Earth life is related, sharing the same DNA.
It likely arose from a single ancestor
• If other planets are like Earth, life could be
common. Meteorites can transfer life.
• The Drake equation calculates the number of
technical civilizations we might communicate
with
Life on Mars?
• Details of life’s origin on Earth are lost
• Mars had liquid water, biogenic elements,
energy when the first life arose on Earth
• Life from Earth? Ejected material can reach
Mars (opposite of Mars meteorites)
• Life on Mars could still survive in some
locations: hot springs or underground. ‘Follow
the water’
• Vikings searched for life similar to Earth, but
did not find it
Where to search for life
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Lake beds
Hydrothermal sites
Recent floods
Underground
Earlier life? If now extinct, look for fossils…
Enough energy? Yes, for 1-2 ft of life!
Conclusion: No conclusion… Look harder,
follow the water, Mars still most Earth-like