Life in the Solar System Run! Aliens! Astronomy

What constitutes life? Group Discussion: What constitutes that something is living? What are some common characteristics of living things?

Life on Earth Common characteristics of life Made up of one or more cells Take in energy to grow and develop Reproduce Give off waste.

Yet, Mars is considered red & dead. What planetary conditions would there need to be for life to be sustained? Video Clip: Star School - Mars Rock found from mars shows possible evidence of fossilized bacteria. What do you think?

Goldilocks Conditions Conditions for life on earth are: suitable temperature range, atmosphere. liquid water If earth were too hot – water vapor would always be a gas If too cold – water would always be solid.

PHYS2010 Life in The Cosmos Extremophiles!

Extreme conditions Discovery of living things in places where it was believed life could not exist. These Discoveries show that life can exist in other environmental arrangements.

Question: think of an environment on Earth where life could not exist It survives in the heavy water in the center of nuclear reactors It survives in volcanoes It survives, even flourishes, at the bottoms of the Oceans It survives INSIDE glaciers (video)

Introduction What are extremophiles? Importance of temperature, pH & pressure Examples of extreme ecosystems

What does the word mean?

Even polyextremophiles!

? ? ? ? ?

Example of an extremophile – “water bears”

Tardigrades – “water bears” The first tardigrades were discovered by Goetz in 1773. Over 400 species have been described since that time. Tardigrades grow only to a size of about 1mm, but they can easily be seen with a microscope. Tardigrade bodies are short, plump, and contain four pairs of limbs Each limb terminates in four to eight claws or discs. They lumber about in a slow bear-like gait over sand grains or pieces of plant material

(please don’t mention these experiments to the animal rights people…)

What does “extreme” mean? If a thermophile that normally lives at 100°C can die at 21°C, or a piezophile from the ocean bottom dies at surface pressure, what do we mean by extreme environment?

Definitions of “extreme” Different from some fiducial environment? Subjective: with respect to human preferences? Objective: with respect to life’s original, but UNKNOWN, location ?

Who is extreme? “Extreme” values of any particular property (pH, T, salinity) are simply values far from the median for that eco variable e.g.: water-based life requires ability to control cell’s T, pH, internal solutes (fuel, building blocks, etc.), biomolecules, electric potential gradients, and be able to repair damage. Anything that varies from these conditions we regard as “extreme”…

Role of Temperature Solubility of gases goes down as temp goes up (impetus for colonisation of land?) Organisms have upper temp limits. Chlorophyll, proteins and nucleic acid denature at high temperatures. Enzymes have optimal temperatures for activity; slow down at low temps. At low temp water freezes; crystals then break up membranes etc. (but the expansion of water to ice means layers of ice ‘insulate’ water below… for most liquids lakes would freeze from bottom up)

pH limits

Rotifers Complex, multicellular animals with a size range from roughly 40 microns to over 2,000 microns. They are in virtually every lake and stream, every pond, on bits of moss in moist forest, in the tropics and even in icy arctic terrains

Pyschrophiles who live in the cold on the tops of mountains Grylloblatids: Pyschrophiles who live in the cold on the tops of mountains Their discoverer was obviously a bit confused by their appearance…: The first species named was Grylloblatta campodeiformis, which means "It looks like a cricket, a cockroach, and a Campodea"

Worms inside Glaciers! video

PRESSURE

This is Life which has never seen The Sun, but has a completely different energy source many km below ocean surface ( any old energy will do…!!)

Mars Surface Temp 210K Atms Pressure 0.007 bars Atms makeup 95% CO2 Gravity 38% earth Other High radiation levels

Venus Surface temp 737K Atms pressure 92 bars Atms makeup 96% CO2 + sulphuric acid clouds Surface gravity 88% earth

Question – are we extreme? ….since oxygen is responsible for significant damage (oxidation) to nucleic acids, proteins, and lipids, WE are extremophiles! !

Good news for life elsewhere in the Comos – maybe even in our own solar system…

What have we learned that’s important for Life in the Cosmos? Life seems to be able to adapt to very extreme environments Life can survive for long periods in stasis and then recover Life can change its environment (oxygen)