Astronomy midterm question: Martian volcanoes reactivating?

Astronomy 210 Midterm 2, spring semester 2014
Cuesta College, San Luis Obispo, CA

An astronomy question on an online discussion board[*] was asked and answered:
py: What would happen if Mars' volcanoes became active again? Like if all of the sudden Olympus Mons just exploded and melted the ice caps? Would Mars' climate become more like Earth's?
Al: (a) It would be impossible for Mars' volcanoes to become active again, but (b) if they could become active, Mars' climate would then become more Earth-like.
Discuss why both these answers (a)-(b) are correct, and how you know this. Explain using the properties of greenhouse gases and geological activity.

[*] Adapted from https://answers.yahoo.com/question/index?qid=20110615233622AAjIa8s.

Solution and grading rubric:
  • p = 20/20:
    Discusses why both statements are correct: (a) Mars' volcanic activity has ceased because there is no heat left in its small core, which caused it to cool off rapidly; and (b) if there was an increase in volcanic activity, outgassing and melting of polar ice caps would introduce more carbon dioxide and water vapor greenhouse gases, allowing Mars to retain more heat from the sun and increase its atmospheric temperatures.
  • r = 16/20:
    Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. One of two points (a)-(b) correct, other is problematic/incomplete.
  • t = 12/20:
    Contains right ideas, but discussion is unclear/incomplete or contains major errors. Both points (a)-(b) problematic/incomplete, or one point correct while other is missing.
  • v = 8/20:
    Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. At least understands factors that contribute to (lack of) volcanic activity and greenhouse effect.
  • x = 4/20:
    Implementation/application of ideas, but credit given for effort rather than merit. Discusses factors other than relevant to geological activity and greenhouse effect.
  • y = 2/20:
    Irrelevant discussion/effectively blank.
  • z = 0/20:
Grading distribution:
Section 30674
Exam code: midterm02n4iL
p: 10 students
r: 6 students
t: 8 students
v: 2 students
x: 2 students
y: 0 students
z: 0 students

Section 30676
Exam code: midterm02sh7F
p: 18 students
r: 5 students
t: 12 students
v: 7 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 0123):

Another sample "p" response (from student 7342):

A sample "t" response (from student 1378), only discussing why Mars' volcanoes cannot erupt again:

Another sample "t" response (from student 6620), only discussing the effect of volcanic eruptions on Mars' climate:

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