The Search for exoplanets and Extraterrestrial Life

• http://www.jpl.nasa.gov/news/news.cfm?release=2011-373

• Kepler mission• Are we alone?http://www.jpl.nasa.gov/videos/phoenix/phx20070724/phx-20070723-1280.m4v

• How did life start on Earth?• Where can we find potentially life supporting

conditions in our solar system?• SETI• Video• Habitable zone

Kepler mission• Kepler mission is looking

for earth like planets. http://

www.youtube.com/watch?v=q1qqJ3AwaBk

CURRENT PLANET COUNT: 687 stars with planets: 474 Earthlike planets: 0 ?As of 12/5/11http://planetquest.jpl.nasa.gov/missions/missions_chart6.html

http://www.youtube.com/watch?v=q1qqJ3AwaBk

1. What is habitable zone?2. What is the primary science goal of Kepler

mission?3. How is that goal achieved?4. How big is Kepler’s field of view?5. How does Kepler see? (What is Kepler’s

sensors?)6. In What direction (constellation) do Kepler

look at?7. What is photometry?

NASA's Kepler Confirms Its First Planet In Habitable Zone

Are we alone?

Planet Quest : NASA JPLhttp://planetquest.jpl.nasa.gov/science

How did life start on earth? • An Updated Miller-Urey Experim

ent

• exposed a mixture of gaseous hydrogen, ammonia, methane and water to an electrical arc for a week. At the end of the experiment, the reaction chamber was coated with a reddish-brown rich in amino acids and other compounds essential to life.

• Chemosynthesis : evolved here & panspermia: evolved elsewhere

Extremophiles• thermophiles: exist in hot environmentsThermus aquaticus, discovered in hot springs in Yellowstone

National Park (70+oC).Pyrolobus fumarii, grows on the walls of black smokers (113oC).

• acidophiles: exist in acidic environmentsSulfolobus acidocaldarius inhabits hot (85C) and sulphurous thermal

springs (in Yellowstone national park)

• psychrophiles: exist in cold environments

Polaromonas vacuolata, which lives in antarctic sea ice. Ice worms fround at sea floor @ 0oC.

• halophiles: exist in salty environmentsThese cyanobacteria survive until @ Shark bay, which is far too salty for any predators to exist in it.

The Search for Life on Mars

• It appears that Mars at some point in its history was very much wetter and warmer than it is today

• Scientists have been looking for life there

• The Viking landers (1970’s) tested for the presence of microbes, but returned inconclusive results

• We are still looking!

Remember Phoenix Lander?

average distance of 1.52 AU from the Sunrotation period = 24 hours 37 minutesorbital period is 687 days. rotation axis is tilted at 25 degrees: seasonsMars's radius ~ half of Earth's, mass is only 10%low surface gravity = 0.38 Earth gravities.

Environment• CO2 thin atmosphere• Erosion due to flash floods• Erosion due to sustained water flow, • Features around the boundaries of the northern lowlands which

may be the shores of an early liquid-water ocean or group of lakes. This would explain why the lowlands appear so smooth.

• Signatures of minerals which can only form in the presence of liquid water, such as sedimentary deposits of crystalline haematite(iron ore).

evidence for ancient Martian life: * tiny, elongated tubular structures around 100 nanometres long, which resemble fossilized microbial life. * pure crystals of iron sulphide and magnetite, which are rarely found together, but can be formed by certain types of bacteria. * polycyclic aromatic hydrocarbons (PAHs), organic molecules which result from the decay of microorganisms.

Europa of Jupiter http://www.jpl.nasa.gov/video/index.cfm?all_videos&id=649

orbits Jupiter: every3.5 days @ d= 670,000kmdensity of about 60%: mostly rocky materialsradius of 1,500km: surface gravity=0.14 Earth’s.Europa's frozen surface with ocean of liquid water (tidal heating)

Europa most likely has organic compounds containing oxygen, carbon, sulphur, hydrogen and nitrogen. Potential life near geothermal underwater vents

investigation of Europa shall include: cryobot, to melt through the surface ice, and a hydrobot, to explore the underlying ocean and look for signs of life.

Possible Europa LifeCracks with freshly frozen water and long faults make it clear that Europa's ice is no more than 100 miles thick. The ocean below surges up through cracks with tidal frequency, water that is likely at 32° Fahrenheit — just at freezing — a tolerable temperature for life.

Titan of Saturn

- Titan is the largest of Saturn's satellitessignificant atmosphere (nitrogen, ammonia, methane and hydrocarbons such as ethane and propane. similar to smog on earth!)- Orbit Saturn every 20.3 days @ d=1.2 million km- mixture of ices (methane & ethane) and rocky compounds, diameter ~5,000 km, (larger than Mercury)- Surface temperatures ~ -180C

The present-day prospects for life on Titan are poor, due to the low temperatures. Titan’s atmosphere and surface are rich in the prebiotic compounds which eventually produced life on Earth.

http://saturn.jpl.nasa.gov/multimedia/flash/Titan/index.html

SETI

• SETI: Search for Extra-Terrestrial Intelligence

• Listens for electromagnetic evidence of intelligence elsewhere in the universe

• To date, evidence has been sparse.

Water hole This graph shows the background noise level from the sky at various radio and microwave frequencies. The so-called water hole is a range of radio frequencies from about 103 to 104 megahertz (MHz) in which there is little noise and little absorption by the Earth’s atmosphere. Some scientists suggest that this noise-free region would be well suited for interstellar communication. Within the water hole itself, the principal source of noise is the afterglow of the Big Bang, called the cosmic microwave background. To put this graph in perspective, a frequency of 100 MHz corresponds to “100” on a FM radio, and 103 MHz is a frequency used for various types of radar.

Since 1995 the SETI Institute in California has been carrying out Project Phoenix. When complete, this project will have surveyed a thousand Sunlike stars within 200 light-years at millions of radio frequencies. At Harvard University, BETA (the Billion-channel ExtraTerrestrial Assay) is scanning the sky at even more individual frequencies within the water hole.

Drake equation

N = R* fp ne fl fi fc L• N = number of technologically advanced civilizations in the Galaxy whose messages we might be able to detect• R* = the rate at which solar-type stars form in the Galaxy(=1)• fp = the fraction of stars that have planets (=1)• ne = the number of planets per solar system that are Earthlike (that is,

suitable for life) (~0.25)• fl = the fraction of those Earthlike planets on which life actually arises

(=1)• fi = the fraction of those life-forms that evolve into intelligent species

(=1)• fc = the fraction of those species that develop adequate technology

and then choose to send messages out into space (=1)• L = the lifetime of a technologically advanced civilization (=200 years?)

The Drake Equation : Putting it all together * R* is well-known * fp is reasonably well-known * ne is uncertain * fl is highly uncertain * fi is extremely uncertain * fc is extremely uncertain * L is extremely uncertain

Based on the above estimates of each term in the Drake Equation, the expected number N of civilizations in the Galaxy which are currently producing electromagnetic signals is 50. Taking the radius of the galactic disk as 15 kiloparsecs, and assuming that stars are spread evenly throughout this disk, then on average we can expect to find one communicating civilization in each 14 square kiloparsecs of the disk (i.e., in each 120 by 120 parsec region, or about 400 light year).