20. Mars Flashcards
What makes a planet habitable
-source of liquid water
-source of energy (lots of redox couples for energy and light on mars)
-source of elements (CHNOPS) and other nutrients
-Suitable physical conditions (Temp, pressure, ph , radiation) (on mars temp In range, ph fine, uv radiation high but can escape)
Why is surface of mars uninhabitable
No liquid water
High ultraviolet radiation (damagesc1000x more th a earth)
Oxidants in the soil
Why was Past of mars different
Evidence of water on mars in the past,
Potentially initially had a high enough pressure that temp cha he of season would not cause liquid water to free over
Atmospheric loss on mars
Lack of magnetic field on mars so solar wind strips away atmosphere
Some evidence of early magnetic field that may have dissapeared?
Atmosphere heats up at small escape velocity bc smaller planet so lose more atmosphere through impact erosion
Hydrodynamic escape, light molecules drags out heavier Molecules
What would have happened if mars was earths size ?
Is there any water on present day mars?
Seasonal brine channels at edges of craters today ?
Briny water on landing legs of phoenix landers, melted when it landed?
Caves where pressure >tripple point
Subsurface, has ice in South Pole could have lake of briny fluids? (Would have to contain something reducing melting point so not good for life )
Is mars habitable
All requirements for habitility on mars seem to be met , with subsurface water
Or I’m the past
Question is was or is there life to take advantage of this
What to look for in search for life?
Shapes of Fossils that resembles life, isotopic signatures of life , organic remains of life, changes in chem caused by life
How do we know Martian meteorites come from mars?
Can extract bubbles of trapped gas from meteorites and find the composition of gases in the meteorites are the same as Martian atmosphere
Some evidence for life in Martian meteorites and why controversial
PAHs found ,grains , look like microbes
Inconclusive
