EPSc 230 Introduction to Astrobiology
Spring 2006
This Week’s Research Questions-Week 5
Instructions:
This week in Discussion Section you will be deliberating as a panel of experts the topic of what would life
most likely be like if we were to detect it elsewhere. Your panel will carefully consider each of the issues
outlined below. Your panel will deliberate and come to a consensus opinion. Your section will then draft
up a written statement of your opinion (should be~ 2 paragraphs). One person will type up the consensus
opinion, send it out to your fellow panel members for comments and then turn in the statement to me. I
will then post the statements on the course website.
Your panel should come up with consensus statements that address the following questions:
1. Do you think life is common or rare in the solar system? Why?
2. What do you think the variables are controlling whether life is common or rare in the solar
system? Is an independent origin of life “hard” (i.e., rare) or is it easy (i.e., common)? Do you
think Panspermia has been rare or common? How might this have changed in the history of the
solar system?
3. What might be the features of that life if it arose by Panspermia?
4. What might be the features of that life if it arose by Independent Evolution?
5. If we go to another planet to look for life, how do we tell whether Panspermia or Independent
Origin has occurred? What specific traits will we look for and how will we look for these
traits?
In your deliberations, your panel should consider the following issues:
1. Panspermia.
a. When was Panspermia more common?
b. What kind of life was around on the earth at that time?
c. Is Panspermia happening today?
d. Are the same kind of organisms that would be transferred today the same as those
transferred in the past?
2. The Tree of Life
a. Think about the structure of the tree of life, where the mesophiles and thermophiles are,
where the photosynthetic organisms are.
b. Think about the relative timing of when these different types of organisms existed or
originated on the Earth.
c. What kind of organisms were around on the earth when life may have been transferred
around by Panspermia?
d. What kinds of organisms are mostly likely to survive the process of Panspermia. How
does this fit in with your conclusions above?
3. Adaptation and Evolution
a. We talked a little about how organisms adapt to their surroundings.
b. Even if certain types of organisms are easily transferred by Panspermia, this doesn’t
mean that only those kinds of organisms will be on another world (just think of our own
tree of life and how things have changed with time).
c. Think about extinction events! Things go extinct and leave no ancestors if they cannot
adapt to changing conditions.
d. Also think about how other worlds (like Mars) have changed over time. How would life
on Mars have changed and adapted with time?
4. Independent Origins Of Life
EPSc 230 Introduction to Astrobiology
Spring 2006
a. Panspermia may not have spread life around the solar system. Maybe nothing can really
survive interplanetary transfer. If this is the case, then life could still be on another world
if there was an independent origin of life elsewhere
b. Think about: If there was an independent origin of life elsewhere, what would you expect
those organisms to be like?
c. Would they be like Earth-life?
d. Think about the 6 characteristics of life individually. Then using these, make predictions
about what this life would be like.
e. Now, think about adaptation and evolution again, this time in the context of an
independent origin of life.