Conversations with the Earth Tom Burbine tburbine@framingham

Conversations with the Earth

Tom [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

• 1 99 19 89 35 84 52 76• 2 98 19 89 35 84 56 75• 2 98 19 89 35 84 57 74• 2 98 19 89 40 83 58 73• 5 97 23 88 40 83 58 73• 5 97 23 88 42 82 60 70• 7 96 23 88 42 82 61 69• 8 95 23 88 42 82 62 68• 9 94 27 87 45 79 62 68• 10 93 27 87 45 79 64 66• 10 93 27 87 45 79 65 61• 10 93 27 87 45 79 66 59• 13 92 31 86 49 78 67 50• 14 91 31 86 49 78 68 44• 15 90 33 85 51 77 69 42• 15 90 33 85 52 76 70 39• 15 90 35 84 52 76 71 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

• 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• 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?