Life on Other Worlds

1
Life on Other Worlds

• Chapter 26

2
Extra Terrestrial Life

• We have been imagining life other than our own
  for most of human history
• Easiest place to look is the Solar System
• Mars
• Europa
• Venus

3
Life on Mars?

• Traces of life in a meteorite from Mars?

4
Water on Mars?

• No longer searching for life, but instead the
  conditions necessary for life
• Liquid water and Carbon
• Water to disolve chemicals
• Carbon to form complex molecules

5
Life on Europa?

• Large ocean detected below the ice
• Probably very salty water heated by tidal heating
• Not much light would penetrate the ice

6
What would it look like?

• A very deep cold ocean with no/little light
• Photosynthesis probably ruled out
• Deep sea life on Earth relies on food from higher
  up where there is sunlight, maybe some other way?

7
Lake Vostok

• A lake formed under the ice in Antarctica could
  give us a better understanding of what Europa
  might be like
• Could we drill down and sample the lake?
• Could/Should we do that on Europa?

8
What about elsewhere?

• More solar systems are found all the time
• Kepler mission looks for terrestrial planets
  using the transit method

9
Do we expect to be able to find life out there?

• Since we cant go there the only life further
  afield than our solar system that we could detect
  would be intelligent/technologically advanced
  beings that would send some sort of signal or
  come to visit us

10
How would we find them?

• Searches by SETI for radio signals or laser
  signals are under way
• Use basic scientific principles to look for
  frequencies we should look at (21 cm line) if
  they are sending on purpose
• Broader search to look for leakage

11
SETI_at_home

• You too can search for radio signals!
• Large compter power is needed to search the
  spectrum for signals, SETI project at Berkeley
  uses 2 million idle computers around the world

12
What about sending a message?

• We started sending messages when radio started
  broadcasting
• In the 1930s we started sending television
  (speeches of Hitler)
• In 1974 we sent a message from Arecibo on purpose

13
What about sending something other than science?

• On Pioneer 10 and 11 we sent a plaque telling
  about us
• On Voyager 1 and 2 we send the Golden Record
  and instructions on how to play it. It includes
  pictures, sounds of Earth and greetings in 55
  languages