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Astronomy 3040
Astrobiology
Spring_2016
Day-9
Project
 http://www.ulalaunch.com/docs/product_sheet/Delt
aIVPayloadPlannersGuide2007.pdf
 This is the Delta-IV payload guide overview. 20MB.
 Planetary quarantine program.
Course Announcements
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Colloquium on Friday, Feb. 19. @2:30pm B310
Dr. David James, Cerro-Tololo InterAmerican Obs.
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Open Clusters, Stellar Evolution and Calibrating the Ages
of Stars: Blanco 1
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Galactic open clusters are laboratories, provided by nature, for
us to study stellar evolution. Using 1m-, 4m- and 8m-class
telescopes, I will show how spectroscopic and photometric
observations of solar-type stars in open clusters allow us to
establish a stellar chronometer, and create an age-ranking
system for an ensemble of nearby, well-studied clusters. With
the aid of new observations of Blanco 1, an high-Galactic
latitude, Pleiades-age cluster, I will show how deriving stellar
age must be based upon very high quality observational data
and a diverse range of stellar models.
ASTR-3040: Astrobiology
The Nature of Life on Earth
Chapter 5
Day 10
Homework
Due Thur. Feb. 10
Chapter 5:

4, 6, 14, 20, 25, 27, 33, 37, 42, 47, 48, 49, 51
Environmental Reqriments
 Atmosphere
 Liquid water
 Temperature
 Pressure
 Radiation
 But, that's for Earth-like life.
 What about other forms of life?
Earth Life
 Use 25 of 92 elements
 O, C, H, N – 96% of mass of living organisms
 3, 4, 6, 1 – abundance in Universe
 2% mass of solar system, < 0.1% in old SSs
 Temperature in protostellar nebula.
 Energy density from Sun
 Liquid water at Earth's distance
 Stays liquid over large temperature range

Facilitates chemical reactions
Earth Life
 Water:
 Liquid over wide and higher temperature range
 Solid water floats
 Charge separation of water molecule
 Environmental Rqrmnts for Habitability
 Source of molecules for building living cells
 Source of energy for metabolism
 Liquid medium for transporting molecules
SS Tour
 Mercury and Moon
 No atmosphere
 No tectonic or volcanic activity
 No volatiles *

Lunar polar ice?
 No magnetic field
 Temperatures
SS Tour
 Venus and Mars
 Venus – similar in size to Earth



Temperature and Pressure (95F w/o greenhouse)
 880F in reality, 90 atm pressure
Atmospheric composition – CO2 (96%)
volcanism
 Mars – smaller, but Earth-like landscape


Probably had liquid water (3 Gyr)
More in next chapter
Jovian Planets
Moons
 Large moons
 Europa, Ganymede, Callisto, and Titan
 Lots of ices
 Small moons
 Phobos, Deimos – too small
 KBOs – too cold
S/C Exploration
 Flyby
 Orbiter
 Lander/Probe
 Sample Return
Astrobiology Missions
 Only those to Mars have been specifically designed to
look for evidence of life. However, several s/c -flown
and planned- look for evidence of water, organic
molecules...
 Mars has a major exploration program
 First sample return scheduled in about 10 yrs
Molecular Components
 Carbohydrates – energy sources
 Sugars and starches
 Lipids – energy stores, barriers
 Fats
 Nucleic Acids – DNA and RNA
Molecular Components
 Proteins – structure & chemistry
 Structural materials
 Enzymes – catalysts for reactions
 Amino Acids (20 used in most life forms)
 Left-handed in biological entities.
Defining Life
What is Life?

We have to know what we're looking for.
6 Key properties shared by most or all living organisms
on Earth.

Order – structure arrangement – necessary condition

Reproduction – viruses and prions

Growth & Development – heredity

Energy Utilization -

Response to the Environment

Evolutionary Adaptation
Role of Evolution
Most biologists regard evolutionary adaptation as the
most important of the six.
Ancient idea - “change with time”
Mechanism of evolution

Darwin – The Origin of the Species - 1859

Based on two undeniable facts and inescapable concl.
Overproduction and competition for survival.
Individual variation
==> Unequal reproductive success.
“Natural Selection”
Evidence for Evolution
1st voyage of the HMS Beagle to Galapagos
13 finch species

Closely resemble each other, but found nowhere else.
Giant armadillo fossiles in Brazil and smaller living
armadillos.
Evidence in “Artificial Selection” - animal breeding
Viruses evolve even faster.
Molecular Basis of Evolution
DNA – changes to the genome with time.

mutations
So, What is Life?

Something that can reproduce and evolve through natural
selection.
Artificial Life?