chemistry of life part 2 Flashcards
why is there optimism about finding extraterrestrial life, even in our solar systems?
Due to the amount of extremophiles living on earth, in conditions of high temperature and high salinity, and inside rocks
what is a halophile?
salt loving creature
what is a biosignature is what?
any evidence or indication of life, living or dead. it can be chemical or morphological in nature
what is the most important biosignature?
Liquid water
What are some more complex biosignatures?
carbs, lipids, proteins, nucleic acids.
the more complex biosignature you find the more likely it is to have had biogenic origin
What is racemization?
one enantiomer can spontaneously turn into the other one
what biosignature is the most relevant to finding/studying alien life?
an atmosphere that is not in chemical equilibrium
why is the earths atmosphere not in equilibrium?
due to the presence of life, methane and o2 are waste gases from organisms
how might we be able to look for life on mars? (7)
look for waste gasses
methane, o2
but also other ones such as;
formaldehyde and methanol
also might look for
chirality
isotopic ratios found only in life
morphological biosignatures
How do we study Mars for evidence of life, present or past? (4)
telescopes
uncrewed probes (flybys, orbiters, landers, rovers, sample return missions)
meteorites from mars
human crewed missions
Ancient mars (3-4 billion years ago) had what? (5)
geological activity (volcanoes)
a liquid core that produced a magnetic field
a thick atmosphere of co2 and water vapour that was protected by the magnetic field from solar wind and cosmic rays
higher temperatures
large bodies of water
What did Allan Hills find?
ALH 84001 A several billion year old meteorite that had been ejected from mars 16 million years ago and landed on earth 13000 years ago
What was interesting about ALH 84001?
organic molecules - polycyclic hydrocarbons
magnetite that might have a biological origin
shapes that look like tiny bacteria
What is Panspermia?
life can travel from one plant to another in our solar system
What happened to Mars? (4)
The core solidified, geological activity stopped, and the magnetic field weakened
solar wind striped away much of the atmosphere which was no longer replenished by volcanic activity
most of the water was blasted into space from meteor impacts.
the remaining water froze in subsurface layer
the study of mars today:
what is the current condition of the atmosphere?
very thin, it is 1% of the earths atmosphere 96% co2 traces of o2 methane and carbon monoxide
the study of mars today:
what is the current condition of the temperature?
very cold, but near the equator when sun is around it can be 0 degrees and ground could be up to 20 degrees
the study of mars today:
what is the current condition of the geology?
no geological activity
the study of mars today:
what is the current condition of the radiation?
it has a lot of radiation
What was the purpose of the Viking lander
to look for traces of life, but came up empty.
What did the ground based observations, the mars express orbiter and curiosity rover detect in trace amounts on mars? what does this mean?
Methane
possible means that there was life?
methane is a biosignature and there is a variation in the concentration of methane in terms of latitude
What are the possible sources of martian methane? (2)
living origin
at high temp and pressure olivine rock and water mixed produced methane
it is very ambiguous sign
What are recurring slope linae?
Suggests that liquid water still flows periodically on mars, although this conclusion is disputed, the streaks are dark colourations
What did the phoenix lander in 2008 discover? (3)
touched down near the north polar cap
subsurface water ice
snow
perchlorate, a strong oxidant which some organisms can use for energy
What did the curiosity rover find?
detected a transient spike in methane
What is the Exomars rover ? what will it have/what is its mission?
Will have large instrument package, including a drill that can go 2 meters below the surface
will carry a large lab that can look for water ice, biosignatures and mineral composition of the surface
