Transcript Linking Asteroids and Meteorites through Reflectance

Conversations with the Earth
Tom Burbine
[email protected]
Final
• May 9 (Monday) – 11:30 am - (Monday, Wednesday,
Thursday class)
• May 11 (Wednesday) – 8 am - (Tuesday, Thursday class)
• 25 short answer questions
• No calculators
• Besides your new sheet of paper, you can bring in the sheet
of paper you used for the Midterm
Grade
Distribution
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1
2
2
2
5
5
7
8
9
10
10
10
13
14
15
15
15
99
98
98
98
97
97
96
95
94
93
93
93
92
91
90
90
90
19
19
19
19
23
23
23
23
27
27
27
27
31
31
33
33
35
89
89
89
89
88
88
88
88
87
87
87
87
86
86
85
85
84
35
35
35
40
40
42
42
42
45
45
45
45
49
49
51
52
52
84
84
84
83
83
82
82
82
79
79
79
79
78
78
77
76
76
52
56
57
58
58
60
61
62
62
64
65
66
67
68
69
70
71
76
75
74
73
73
70
69
68
68
66
61
59
50
44
42
39
38
• 15
90
35
84
52
76
72
25
Types of Planetary Missions
• Fly By
• Orbiter
• Lander
– Atmospheric Probe
– Rover
– Manned
• Sample Return
Water on Mars
• Most of the water is frozen (permafrost and polar
caps)
• No bodies of liquid water, which could create a
hydrosphere
• Only a small amount of water vapor is in the
atmosphere
How did Mars lose its water?
How did Mars lose its water?
• One possibility:
• On Earth, we're protected from the solar wind by
a global magnetic field
• Mars appears to have had a global magnetic field,
which turned off
• When it turned off, Mars’ atmosphere may have
been eroded by the solar wind
Basic Definition of Life
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Growth
Metabolism
Motion
Reproduction
Stimulus response
ALH 84001
• Allan Hills 84001
• Martian meteorite found in Antarctica
• Thought to have evidence for life (1996)
Meteorites from Mars
• Are called SNCs
• Shergottites, Nakhlites, Chassignites
– Shergotty
– Nakhla
– Chassigny
• 34 Martian meteorites currently known
How do we know they are from Mars?
• Most have young formation ages (1.35 and 0.15
billion years)
• Gases in glass in meteorites match Mars
Evidence
• organic molecules
• Magnetite (Fe3O4) that looks like it formed from
biologic activity
• nanofossil-like structures
Age of ALH 84001
• ALH 84001 - 4.5 billion years
• But has same oxygen isotope ratio as other
Martian meteorites so it comes from Mars
• Oldest meteorites are 4.56 billion years
Face on Mars
Face is 1.5 km across
Significant Mars Missions
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Viking 1 (1976-1982) (NASA) (Lander)
Viking 2 (1976-1980) (NASA) (Lander)
Mars Global Surveyor (1993-2006) (NASA) (Orbiter)
Mars Pathfinder (1997) (NASA) (Lander)
Mars Express (2003-present) (ESA) (Orbiter)
MER Spirit (2004-present) (NASA) (Lander)
MER Opportunity (2004-present) (NASA) (Lander)
Mars Reconnaissance Orbiter (2006-present) (NASA) (Orbiter)
Phoenix (2008) (NASA) (Lander)
Viking Missions
• Each spacecraft consisted of an orbiter and a
lander
• Viking 1 lander landed July 20, 1976
• Viking 2 lander landed September 3, 1976
• Total cost was ~1 billion
Viking 2
Viking 2
Four Experiments
• There were results that were initially positive
• But results could all be explained through non-biologic
chemistry
• For example, Labeled Release Experiment
– The nutrients were tagged with radioactive 14C
– Looked for emitted 14CO2 gas as evidence for
chemical reactions that happen in living
organisms to maintain life
– Radioactive gases were given off
immediately for
the first insertion of nutrients
– Subsequent insertions did not give off
radioactive
gases
Europa (Moon of Jupiter)
Europa
• Very smooth surface
• Its albedo is one of the highest of all moons
• Lack of craters indicates a young and active
surface
• Thought to have a liquid water ocean
• Possibly abode of extraterrestrial life
• Symmetric ridges in the
dark bands suggest that
the surface crust was
separated and filled with
darker material,
somewhat analogous to
spreading centers in the
ocean basins of Earth.
• Spectroscopy suggests that the dark reddish
streaks and features on Europa's surface may be
rich in salts such as magnesium sulfate (Epsom
salt), deposited by evaporating water that emerged
from within.
Europa
• It is thought that under the surface there is a layer
of liquid water kept warm by tidally generated
heat.
Proposed Europa Jupiter System
Mission (NASA/ESA) (~2020)
Any Questions?