HOW DO WE SEARCH FOR LIFE IN THE UNIVERSE?
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Transcript of HOW DO WE SEARCH FOR LIFE IN THE UNIVERSE?
HOW DO WE SEARCH FOR
LIFE IN THE UNIVERSE?
The Search for Life
Robotic Emissaries
Remote Detection
Robotic Emissaries Pioneer 10 & 11
(1972/3) Voyager 1 & 2 (1977) Traveling 23,000 –
39,000 mi/hr Essentially no
onboard guidance system
Random encounter with a stellar system in 1019 years
The Search for Life on Mars
Giovanni Schiaparelli (1877)
Percival Lowell (1894 – 1916)
The “Face” on Mars
Martian Meteorites
Nodules of carbonate
Crystals of iron pyrite
PAH’s (organic material)
Fossil bacteria?
Life on Mars?
History of thicker atmosphere
History of water
Probable Earth-like geologic history
Viking I & II(1976)
Viking Biology Experiments
No organic compounds found in soil
Atmosphere: very small amounts of methane and nitrogen
Biological experiments based on Earth-like life (is this realistic?)
Three biological experiments performed on Martian soil
Viking Biology ExperimentsGEX: Gas Exchange – “feed” the soil
Gas chromatograph measured composition of gasses in chamber before/after feeding
LR: Labeled Release – look for respiration
Look for radioactive carbon in gaseous form.
PR: Pyrolitic Release – “Roast” the soil
look for radioactive carbon in atmosphere.
Viking Biological ExperimentsResults:
All 3 gave positive results!
BUT! All positive results can be produced by non-biological chemical reactions.
Pathfinder(1997)
Europa OceanExplorer (2008?) Arrive 2012
The Search for Life:Remote Detection
If it existed we currently couldn’t detect itWhy?
We can detect the presence of extrasolar planets
We cannot image the planets themselves
Light from host star is too overwhelming
What technology is necessary?
Interferometry for high resolution
Space based or ground based
Nulling technology to reduce glare of host star
Nulling Technology
What Do We Look For?
Image extrasolar planets (if not planets maybe their moons)
Look for chemical signatures for life
Make detailed images of extrasolar planets
Planetary Imaging
Interferometric Projects (ground based):
Palomar Testbed Interferometer
Keck Interferometric Array
CHARA (Mt. Wilson) Others…
Space Interferometry Mission(SIM, NASA) Lower mass limit of 5 earth
masses detection out to 10 parsecs (33 LY)
Lower mass limit of 1 earth mass detection out to 16 LY
Terrestrial Planet Finder (TPF, NASA) Detection of 1 earth-mass
planets out to a distance of 50 light years
DARWIN (ESA)
Planetary Imager (PI, NASA)
6000 km baseline
8-m telescopes
Last Week: Chapter 16: 401 – 409 Questions: 5, 6, 7
This Week: Chapter 14: 335 – 357 Questions: 1-7, 11