Life from Space Flashcards
Key requirements for life
Carbon
Liquid water
Energy source
What is the primordial soup idea?
Life formed in pools of water and molecules where reactions can occur
What is the Miller-Urey experiment?
Took molecules which were believed to represent the major components of the Early Earth atmosphere and put them into a closed system
What did Muller-Urey gases did they use?
Methane, ammonia, Hydrogen, Water
What Miller-Urey do to simulate lightning storms?
Ran a current through the system
What were the results of the Miller Urey experiment?
End of one week: 15% of carbon now in the form of organic compounds, 2% had formed some amino acids. Showed organic compounds could be made easily under the conditions of early earth.
Why is carbon important?
Can form chemical bands with many atoms
Can easily dissolve in water
Forms double bonds
Why not Silicon?
Silicon bonds to weak
Interacts with few elements
Only forms single bonds
How much more abundant is Silicon?
1000x more abundant than carbon
Why water is needed for molecules?
Water is needed to be a medium for molecules to dissolved and chemical reactions to occur.
What are some potential sources of energy in early earth?
Sun
Shock waves
Lightning
Lava 1000c
What is the Panspermia idea?
Life floats as life through ISM and occasionally rests on a planet
Types of Panspermia
Basic
Radio
Ballistic
Modern
Pseudo
Directed
What is the Hoyel-Wickramsinghe model:
All life on earth arrived from space, from the galactic center where abiogenesis occured
Two problems with Hoyel-Wickramsinghe Model
-Goes against long-established soup theory
- mixing of scientific disciplines
Basic Panspermia: Cometary life
Can contain water
Anaerobic bacteria could survive on warm interior
Comets shed material onto surfaces of planets
Potential life in Comet Hale
Showed the small particles in its tail lined up with microbial culture + olivine
How much do debris do comets bring?
100 tons per day
What could bugs from comets do?
-Not interact with terrestrial life
- Add to the genomes of the planet
- Attack terrestrial lifeforms
What was the Weber and Greenberg experiment?
Exposed bacterial spores to 2,500 years radiation exposure and 0.1% survived. If coated in dust they are shielded
How long would stellar journey times be for bacteria?
-If from planetary nebula then move at 1000 km/s so 100,000 years
Example of extreme survival on the moon
Found specimens of streptococcus mitis on camera left on the moon for 30 months from someone sneezing
What does moon survival tell us?
Vacuum of space is not a fatal problem for bacteria. They can undergo cryptobiosis to survive in extreme temperature swings
New theory for where life formed on earth
Around volcanic vents as water is heated
