Astrobiology: A Planetary Prospective PTYS 214

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Astrobiology A Planetary Prospective PTYS 214

• Space Sciences 308
• Tuesdays and Thursdays
• 930 a.m. - 1045 a.m.

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Professor
Alexander Pavlov Office Space Sciences
401 Phone [phone] Email pavlov_at_email.arizona.ed
u Office hours Fri 1500-1700 or by appointment
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Teaching Assistants
Vijay Veerasamy Email vkvijay_at_email.arizona.edu
Office hours TBA 330 Kuiper Space Sciences
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Class Web Site

• http//www.lpl.arizona.edu/undergrad/classes/fall2
  008/Pavlov_214
• Check for
• Lecture notes
• Homework assignments
• Review sheets for exams
• Other information

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• No textbook
• All lecture slides will be posted on the web
• You are expected to take notes

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Grading
1 midterm exam 20 Tuesday, October 14 8-10
quizzes 20 8-10 homeworks 30 1 final
exam 30 Tuesday, December 16
800 a.m. 1000 a.m. Extra credit Student
presentations up to 10.
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Grading (continued)
Grades will be determined as A ?87.5 B 75.0
- 87.4 C 62.5 - 74.9 D 50.0 - 62.4 E lt 50.0
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Exams

• There will be 1 in-class, 1-hour exam on Tuesday,
  October 14
• The final exam will be given on Tuesday, December
  16, 800 a.m. 1000 a.m.
• Exams are multiple choice and short essay
• Makeup exams instructor must be notified in
  advance. Makeup exams will be all essay.

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Make-up Exams
Make-up exams are available if you are absent
for 1) A University approved activity 2) A
medical emergency for which you can provide a
doctors note 3) Jury duty 4) Other situations
will be evaluated on a case-by-case basis
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Homeworks

• Homework is due in class on the date listed
• Homework is graded on a 5-10 point scale
• 2 points off for each day late (exceptions
  medical emergency with a doctors note or jury
  duties).
• Homework can not be e-mailed hard copies only.
• Each student is required to write up his or her
  answers independently. No cut-and-paste!

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Quizzes

• Current and/or previous lecture
• Quizzes are graded on a 5-10 point scale
• The lowest score will be dropped
• You can ask for a make-up quiz if you are absent
• A University approved activity
• Medical emergency
• Juror duty

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Cheating

• You will be given 0 pt for cheating on
  assignment (quiz or homework)
• Cheating on exams will result in immediate
  failure in the class
• In all cases a letter will be sent to the Dean of
  Students describing the incident

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Classroom Behavior

• No Food or Drink permitted in the classroom.
  Water is fine
• Pagers/cell phones should be off
• Disruptive behavior will be reported loud
  talking, leaving in the middle of a lecture
  without prior notice to instructor

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Student Presentations

• Articles in Astrobiology from Scientific American
  Journal, Nature, Science, Astrobiology Journal,
  International Journal of Astrobiology approved by
  instructor (1 week prior to presentation)
• 15 min presentations, teams of two-three students
• Increase your grade by up to 10

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Examples of student presentations

• Are Aliens Among Us?
• Is it possible that GRBs damage planetary
  biospheres?
• Life in Planet around M Stars
• Permian-Triassic Extinction

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Course Outline

• Introduction
• Follow the Carbon
• Follow the Energy
• Follow the Liquid water
• Life on Earth
• Life on Mars
• Life on Jovian Moons
• Life beyond the Solar system

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What is Astrobiology?

• A mix of Biology, Chemistry, Planetary Science,
  Climate, Astronomy, Geology
• How does life begin and evolve?
• Does life exist elsewhere in the Universe?
• What is the future of life on Earth and beyond?

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1) How does life begin and evolve? 2) Does life
exist elsewhere in the Universe? 3) What is the
future of life on Earth and beyond?
Science
Religion
vs.
Testability required
Testability not required
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Observations
Question
Revise the hypothesis
Hypothesis
Prediction
Make more predictions
Test or additional observations
Negative
Positive
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Why now?

• Early evidence of life (3.6-3.8 Gyr ago)
  Geology
• Extrasolar planets (306 planets) Astronomy
• Water on Mars (Odyssey mission) Planetary
  Sciences
• Extremophiles
• Biology

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Challenges of Astrobiology

• Humans cannot make life out of the abiotic
  materials (so far)
• Only one example of the biosphere (so far)
  Earth. But stay tuned for results from Phoenix
  mission.
• Humankind is not
• good at space travel

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• What is life?
• How would we distinguish between living and
  not living?

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Properties of Life

• Order
• Reproduction
• Growth and development (directed in part by
  heredity)
• Energy and utilization
• Response to the environment
• Evolutionary adaptation

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Necessary vs. Sufficient Conditions

• A cannot be true unless B is true (B is a
  necessary condition for A)
• If B is true then A has to be true (B is a
  sufficient condition for A)
• Condition living in New York City Effect
  living in the United States
• Condition not smoking Effect living long

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Order, Growth etc. are necessary conditions for
life but not sufficient.
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The origin of species by means of natural
selection (1859)

• Any population of a species has the
• potential to produce far more offspring
• than the environment can support with
• resources.
• 2) The overproduction leads to a struggle
• for survival among the individuals.
• 3) Population consists of individuals
• that are slightly different from one
• another in many heritable traits.
• 4) Some individuals possess traits that make
• them better able to compete for resources.
• Conclusion In any local environment, heritable
• traits that enhance survival and successful
• reproduction will become progressively

Charles Darwin (1809-1882)
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Natural Selection (Darwinian Evolution)
All finches on the Galapagos Islands had a
common ancestor from South America. But! All 13
species adapted to particular microenvironments.
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Artificial Selection
Descendants of a gray wolf
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Non-living objects are not a subject to Darwinian
Evolution
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Definition of Life

• A system capable of evolution by natural
  selection (Carl Sagan, 1970)
• A self-sustaining chemical system capable of
  undergoing Darwinian evolution (NASAs
  definition)

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But!

• Mules cannot reproduce
• Viruses and parasites are not self-sustaining

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Homework 1(PTYS 214)due Thursday September 4

• Based on our discussion in class write a 1-page
  essay on the following questions
• Do you think computer programs that can reproduce
  and evolve (e.g. computer viruses) are alive? Why
  or why not?
• What if these computer programs evolved to the
  point where they could operate machinery to build
  other computers?
• Do you think it is possible to create life on a
  computer?

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Basic Necessities for Living Organisms

• NASAs definition of life is not very useful in
  search for the extraterrestrial life
• In searching for life we need to know the
  ecological requirements for life
• Carbon organic molecules, nutrients (N, P, Fe
  ..).
• Energy (food)
• Solvent liquid water (H2O)