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An Aspect of Astronomy: Life Forms on MARS, organisms that live in extreme…
An Aspect of Astronomy: Life Forms on
MARS
Life and its Requirements
requirements for life
"biogenic elements"
necessary for life processes
tend to live a "carbon-based" lifestyle, with carbon chemistry being Earth's primary makeup (biosphere, atmosphere, geosphere, hydrosphere)
DNA
Proteins
Fats & Lipids
Fossil Fuels
Carbohydrates (e.g. glucose)
carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur
(CHNOPS)
make up 98% of living matter on Earth
organic molecule formation
Earth is made up of these molecules
"building blocks of life" - chemical reaction "reactants"
energy source
energy powers reactions for life
SUN
(primary form)
used in photosynthetic reactions
energy stored (glucose)
cellular respiration
= ATP PRODUCTION (energy)
transported into other organisms
1 more item...
heat source
liquid water
chemical reactions
reaction medium
(reactions can occur successfully)
METABOLISM
all reactions in organisms for survival
solvent
(used to dissolve substances)
movement of molecules (nutrients) in cells (life processes)
organism consumption of dissolved nutrients
temperature regulation
(homeostasis)
controls
turgidity
(pressure) in plant cells
PHOTOSYNTHESIS REACTANT
life derives from photosynthesis
adequate environment
atmosphere
protection from radiation
respirable gases (O2), temperature regulated (traps heat)
magnetic field
extremophiles
(micro)organisms
archaea (single celled prokaryote - differ from bacteria)
"extreme environment organisms"
adapted to extreme conditions opposed to "regular"
biological adaptations
unique cell wall, distinct rRNA, proteins (enzymes), cellular function, biofilms
bacteria (single celled prokaryote -
bacteria
)
lactobacillus (probiotic), E. coli, pathogens
eukarya (single/multi cellular eukaryote)
"three domains of life"
diversity of life on Earth
Mars Environment
atmosphere
thin, composed of: CO2 (g), N (g), and Ar (g)
BP decrease
dust in atmosphere "suspended" - toxic (silica, perchlorate, iron oxides)
little protection:
meteorites, asteroids, comets | cosmic radiation & UV
temperature
high:
20°C |
low:
-153°C
winds = dust storms
past mars
water on mars
ancient river valleys
Adam Losekoot: Open University study
deltas
lakebeds 16,000km
minerals (clays)
potential flooding
rock
current
water exists
thin atmosphere prevents surface water
ice under surface
brine (salts) - water flows hillsides
Olympus Mons
= largest volcano
Earth Environment
considered diverse - supports diverse life
considered "hospitable" - chemicals, water (71% of planet = ocean) & energy =
abundance of life
atmosphere
78% N (g), 21% O2 (g), and 1% other
high protection
protects from sun radiation | meterorites
magnetic field:
due to nickel-iron core & rotation = magnetic field
could life exist on Mars?
potential life in polar "martian ice" - microbes
enough sunlight for photosynthesis (3m deep) in "meltwater" below ice
evaporation prevented (upper ice)
protection from radiation
for conditions
extremophiles
organisms that live in extreme environments
acidophile
low pH environments
strengthened cell membrane | production of biofilms (group of microbes attach = produce slimy protection) | regulation processes of internal pH
psychrophile
low temperature environments
adapted enzymes for low temperatures | "anti-freeze protein" to prevent ice crystals | cell membrane adapted (fatty acid low freezing point) - movement
piezophile
(hydro) |
barophile
high pressure (water | general)
anaerobic extremophile
little to no oxygen environments
anaerobic respiration (pot. fermentation) | use other elements to respire (NO3, SO4, Fe, CO2) | enzyme adaptations | symbiosis (parasitism)
thermophile
high temperatures > 40°C
adapted enzymes to function at higher temperatures (TAQ polymerase)
alkaliphile
high pH environments
adapted enzyme for high pH | regulation
toxitolerant
toxic conditions = ionising radiation
DNA fractures/breaks - adapted to reassemble (broken DNA shredded, enzyme will bond healthy DNA together)
halophile
high saline environments
adapted regulation to protect cytoplasm from salt
Identified
California "Mono Lake":
Spirochaeta americana
microbe lives in alkaline, highly saline (evaporation) & anaerobic environments
Methanopyrus kandleri
: anaerobic methanogen (respires with hydrogen and carbon dioxide) - lives in hydrothermal vent
hydrothermal vent:
extreme temp, pressure, lack of oxygen, salinity
Deinococcus radiodurans
: resistant to radiation - sewage, dust, soil
Methanococcoides burtonii
: Ace Lake Antarctica (-1°C - 9°C) - thriving in -2.5°C
Halobacterium salinarium
- Dead Sea (300ppm) salinity
biochemical reactions required to sustain life
excretion of waste (e.g. transport in cells, urine)
allow for survival and reproduction
adaptated enzymes (e.g.) have been applied to biotechnology (PCR), etc
studies have looked for past life
no
magnetic field - though remains of magnetised dust suggests prior field (NASA)
polar
"martian ice"
CO2 ice and H2O ice
dust on Mars solidification
sunlight absorbed by darker dust, causing melting
"subsurface melted pools"
atmosphere makes melting difficult on surface, but below = melting can occur
"cryconite holes"
habitat?
high-energy "cosmic radiation"
thermophile, halophile, etc
fungi, plants, animals
dormancy in ice (Alaska)
5x greater than ocean (35ppm)
prevent desiccation: produce similar substance to salt - osmotic process regular
100°C
half size of Earth | 1.5 "astronomical units from sun | 2 moons | red surface (oxidation & mars)
evidence
little atmosphere = sun heat escapes
lack of O2
• psychrophile
• anaerobe
•toxitolerant
Alex Jones: Perseverance rover - sample clay
(4 billion years)
(formation from water and aluminium phyllosilicate reaction)
NASA: finds organic matter and carbon (2 to 3 billion years)