Test 2 Flashcards
What is nucleosynthesis?
process that creates new atomic nuclei from pre-existing nucleons, primarily protons and neutrons
Tell me about the Big Bang Nucleosynthesis?
-90% of the universe is composed of H and He
-Almost all H, He were created in the first 3 min after Big Bang
-universe cooled enough for H atoms to form, then fuse to form HE
-H + H =H2
-H2 + H2 = He
-Process ended after ~ 20 minutes (cooled and density decreased as early universe expanded
-Earliest nebulae composed of 3/4 H and 1/4 He (no stars yet)
Review: what’s a Nebulae?
patchy cloud of gases and dust
what was the periodic table right after the Big Bang?
H, He, Li ,Be
Stellar Nucleosynthesis, tell me about it?
-started; 500 may after B.B
-larger atoms made from smaller under high heat and pressure
-nuclear fusion and fission
during stellar nucleosynthesis, atoms gets released from a star, explain it…
-it happens during its lifetime via the stella wind
-as it dies, samll and medium starts become red giants, large stars become supernova explosions
-all elements starting with C produced this way
-stars are element factories
Triple-alpha process is an example of what?
2 Helium atoms forming Be,
Be + He = C
What is cosmochemistry?
study of chemical composition of matter in the universe and the processes that led to those compositions.
Natural samples: meteorties, asteroids, comets, returned samples
Remote spectroscopy: planets, stars, nebulae
Numerical modeling
what is a meteorite?
An extraterrestrial rock that survives an impact on the Earth
what’s the development of cosmochemistry in 20th century? (3)
1- invention of isotope mass spectrometer measure isotope ratios
2-apollo program and state-of-the art analytical facilities to anylyse lunar samples
3-allende carbonaceous chondrite meteorite
what is the Hourglass Nebula?
a young planetary nebula
where do meteorites come from?
material that is as old as S.S and provides scientists with a record from the early solar nebula
what are carbonaceous chondrites?
stony meteorites that have retained many of their chemical properties since their formation 4.56 billion yeas ago
why are carbonaceous chondrites important?
major focus of cosmochemical investigations
what’s a prime example of carbonaceous chondrite?
Allende meteorite
what do the most primitive meteorites contain?
small amount of presolar grains (older than S.S) coming from supernovae
what are the most abundant elements in the earth’s crust?
Si + O
what are 5 silicate mineral examples?
-feldspar
-quartz
-olivine
-Mica
-Pyroxene
who completed the first crewed trip behind the far side of the Moon?
Apollo 8, dec 1968
What were some early ideas about the Moon?
Plutarch:
-Moon had deep recesses; shadows of rivers or deep chasms
-entertained the possibility that the Moon was inhabited
Was the Moon highly reflective which if so, meant what?
according to William Gilbert
yes and it meant covered in oceans
Earlier science ideas:
what was the 3 hypothesis?
1- Fission; early Earth spun so fast it spun off the moon when it was still molten (Darwin)
2-Capture; Moon formed somewhere else in solar system where there was little iron, then captured into orbit around earth by gravity
3-Coaccretion; Moon is a sister world that formed in orbit around Earth at the same time
What was pre-Apollo knowledge?
-Moon density = 3.3 g/cm^3
-Close to Earth’s mantle
-Moon is fluffy, loose dusty
what does Maria mean towards the Moon?
seas in latin.
Smooth, low-lying plains
-few craters (younger)
what does Highlands mean towards the Moon?
Higher elevation
Numerous craters (older)
what are the 2 In situ experiments in Apollo science?
1-Laser ranging reflectors for distance of Earth-Moon
2-Seismometers for internal structure of Moon and Moonquakes
what did the Apollo science bring back from the Moon?
samples of rocks and soil
what’s the total mass that we’ve extracted from the Moon and brought back to study?
383 kg
What are Mare Basalts?
-fine-grained, dark coloured volcanic rocks
-3.2-3.9 Ga
-Low iron, low volatiles
what are Highland Anorthosites?
-Coarse-grained, light coloured, plagioclase feldspar-rich plutonic rock
-4-4.4 Ga
-Low iron, low volatiles
what are Impact breccias?
-Heterogeneous, irrefular sized and shaoed fragments of other rocks
-Majority of Apollo samples are breccia so important on the Moon
what is regolith?
-loose soil
-created by slow meteoritic bombardment (impacts)
-Over time, material is mixed vertically and horizontally by impact processes
during fractional crystallization, which crystalise first during magma ocean and crust formation?
inside completely molten magma, olivine and pyroxene then plagioclase feldspar floats and makes crust
what are the 3 steps in the formation of Maria?
1-impact
2-ring mountains and melt
3-mare filled with lava
which of the 3 early science hypothesis failed ?
all of them
-Fission: because total angular momentum proved it could not form that way
-Capture; lunar rocks showed same isotope composition as the earth
-coaccretion; could not explain the Moon’s lack of iron
what is the giant impact hypothesis?
another smaller pla netary body, The, hit earth in its growth process, blowing out rocky debris.
Fraction of that debris went into orbit around Earth and aggregated into the Moon
what’s the problem with the giant impact hypothesis (old version)?
Moon should be made mostly of Theia material but it shows more isotopic ratios of those on earth
what is identical between the Moon and earth?
oxygen isotope ratios
what else supports the Giant impact hypothesis?
-Earth spin and Moon orbit in same direction
-Magma ocean on Moon difficult to form by accretion; possible with giant ..
-Moon depleted in volatile elements
-Giant impact is consistent with Nebular Hypothesis
-Large collisions in other star systems give debris disks as well
what’s the new version of the giant impact hypothesis?
Theia vaporized and rotates synestia instead of impact then center cools to form earth and the outer remnants form Moon.
what are tectonics?
large scale structure and deformation of a planet’s crust
on Earth we have … tectonics:
plate tectonics
what are the differential stresses of tectonics?
-compressive forces (folding and faulting)
-Tensional forces (stretching and thinning, faulting)
-Shearing forces ( shearing and faulting)
what do all the differential stresses have in common?
faulting for each scenario
what is hot spot volcanism?
when there’s a mantle plume and it drives through the oceanic lithospheric crust and pops out
have planets cooled down or heated up since their formation?
cool down
what do plate tectonics require on Earth?
1-mantle convection = engine
2-cool rigid crust = allows for plates (lithosphere)
3-water =lubricates and allows partial melting
is mercury and the Moon tectonically active?
not anymore
how long has the moon been inactive ?
3 billion years
NWA 773, what is it? how old is it?
lunar meteorite containing a large piece of olivine gabbros rock
2.865 billion years old
what does the light gray part of the meteorite NWA 773 mean?
an impact breccia made of tiny fragments of other rock
what is the youngest lunar rock known?
NWA 773
how long has Mercury been inactive?
3.7-3.9 Ga
does mercury have hints of past tectonics? if so, what are they?
yes,
-faults and ridges suggest compressive forces
-suggesting that mercury contracted slightly as it cooled
what does Mercury do as it cools down ?
contracts creating lobate scarps and thrust faults
why does mercury contract when it cools?
because cooling of a one-plate planet can lead to contraction
weird terrain suggest what?
-caloris impact
-surface waves
-shock waves
-surface disruption at antipode
Has Mars taken longer to cool down compared to the Moon and Mercury?
yes, because it’s bigger
what are big indication of activity on mars?
large volcanoes
could mars still be active today?
yes, we aren’t sure though
what does Tharsis Montes contain on Mars?
-Olympus Mons
-Ascraeous Mons
-Pavonis Mons
-Arsia Mons
How did the crustal dichotomy form?
single impact
multiple impacts
tectonics/mantle processes
paleo shorelines
volcanism (tharsis)
volcanic lava flow
hybrid origin
what is Venus’ features? (7)
-relatively smooth surface
-extensive volcanic features
-large mountain chains
-impact basins
-no obvious plate boundaries
-few impact craters
-young surface
so on Earth, subduction of cold lithospheric plates happen at convergent boundaries, why doesn’t this occur on Venus?
because Venus’ surface is too hot for oceans to exist meaning the subducting slabs aren’t lubricated by partial melting infused by water. hence venus cannot have subduction. also the lithosphere is too hot so it wouldn’t be able to subduct
what type of tectonics does Venus have?
blob tectonics
what are blob tectonics characteristics?
-mantle convection’
-lithospheric movement
-no individual plates
-so subduction (no water)
-abundant volcanism
what is the most geologically active body in S.S?
Io, innermost Galilean moon
what activity does Io have?
-volcanic
-tidal heating
-partial melting
-tectonic mountains related to compression from accumulated volcanic material
tectonics on europa are called what?
cryotectonics
what is planetary habitability?
the measure of a planet’s or a natural satellite’s potential to develop and mantain environments that can sustain life
Habitable environments are or aren’t locations where life might arise?
aren’t.
life may develop directly on a planet or satellite or be transferred to it from another body
what’s the theoretical process where life is transferred from another body?
panspermia
what are the 2 breakthroughs?
1-observation and robotic spacecraft exploration of other planets and moons within the S.S provides information defining habitability criteria and allowed for substantial geophysical comparisons between Earth and other bodies
2-discovery of extrasolar planets leading to the study of extraterrestrial life
what and where is the Habitable Zone? (CHZ)
the goldilocks zone where a planetary-mass with sufficient atmospheric pressure can support liquid water at their surfaces
Earth is located in the CHZ
What’s problems with the concept oh CHZ?
a lot of liquid water believed to occur outside the CHZ
-by tidal heating, radioactive decay or pressurized by other non-atmospheric means
-basic conditons for water-dependent life can be found in interstellar space
what does exoplanet K2 18b have?
water vapor and possibly rain clouds, but no solid surface
why is Earth a habitable planet?
-liquid water on the rocky surface
-carbon cycle
-energy source
-protection from radiation
magnetic field + ozone
what’s important about Mars? (5)
-very dry
-subsurface ice
-cold
-lost its magnetic field and its atmosphere
-exposed to harmful UV radiation
What did Mars become into?
warm water to cold and dry
was early mars habitable?
yes
does venus have liquid water?
no, its too hot
what is concentrated in Venus’ atmosphere?
Phosphine (PH3)
what is astrobiology?
the study of the origin evolution, distribution, and future of life in the universe
what do we search for in astrobiology?
life in extreme environments following the molecular phylogeny (tree of life)
what is the purpose of sample return missions?
-collect and return samples from an extraterrestrial location to earth for detailed analysis
what do samples contain?
atoms and molecules to ‘soils’ and rocks
what are some missions and their locations? (8)
-Apollo and Luna = Moon
-Genesis = solar wind particles
-Stardust = comet Wild 2
-Hayabusa = asteroid 25143 itowaka
-Fobos Grunt = Phobos (failed mission)
-Hayabusa-2 = Asteroid Ryugu
-OSIRIS-Rex = Astreoid Bennu
-Mars (20??) = Jezero Crater on mars
what’s important about sample return missions?
-allows use of state-of-the-art analytical techniques and instruments, providing best possible sensitivity, resolution, precision and reliability
-analyses are iterative and fully adaptive-results are not limited
-analyses can be replicated, verified, done with multiple techniques by different reasearchers
-allows investigation of complex questions
what are the disadvantages of SRMs?
-adds significant cost and complexity to missions
-could fail
-can reduce in situ capabilities
-hazards (planetary protection)
what’s the objective of Genesis?
improve our knowledge of solar compositioon by bringing back pieces of the sun
what do we know about the sun?
it continuously sheds some of its outer layer in the form of solar wind (Genesis)
what happened to the Genesis mission?
sample return capsule crash-landed in Utah
despite the crash of Genesis, what did they find?
-elemental and isotopic composition of noble gases = solar wind composition hasn’t changed
-oxygen isotopes = unknown process depleted O16 in Sun’sprotoplanetary material
-Nitrogen isotopes: poorer N15 than Earth’s atmosphere
What did Stardust do?
passed through dense gas and dust surrounding the icy nucleus of Wild-2
collected with aerogel in a capsyle and parachuted to Earth
what’s a comet?
cosmic snowballs of frozen gases, rock, dust that orbit the Sun
what do short-period comets form?
disc-like belt of icy bodies
what do long period comets form?
Oort Cloud
what’s an example of a comet?
Halley’s Comet (1P/Halley)
what were the results of stardust?
-expected to find pre-solar dust grains (stardust), instead found rocky material formed at high temps in our inner S.S
-found few pre-solar grains
this means materials that were sprayed all over the young solar system and must have been incorporated into all planets and moons
what was first found in a comet from the stardust mission?
amino acid, glycine
what was glycine used for in comets?
used to make proteins in living organisms
what was consistent with extraterrestrial source?
carbon isotopes
what did glycine and carbon isotopes support?
the idea that the fundamental building blocks of life are prevalent in space
this means what for fundamental building blocks of life?
life in the universe may be more common than rare
was early Earth seeded with building blocks for life?
yes
what is a Near-Earth Asteroid?
a NEO is a solar system body that is closest approach to the sun is less than 1.3 AU
what have NEA’s played a role in?
shaping geol and biol hsitory of earth by
-impacts
Missions include:
haybusa 2, OSIRIS-Rex
Hayabusa (JAXA) was what tyoe of mission?
Sample return mission
-1st controlled mission landing on an asteroid
-1st asteroid sample return
= studies of meteorites are hampered by the lack of understanding of their parent body
Hayabusa results:
itokawa = NEA
Rubble-pile asteroid
1500 grains recovered
where did Hayabusa-2 arrive? what did they expect to find?
asteroid Ryugu
preserve some of the oldest material in solar system: ice , minerals, organic compounds
what did they find on asteroid Bennu?
cabonaceous NEO
key components of organic molecules necessary for life
what did they observe on mars in 17th and 19th century?
Cosmotheoros
-life requires liquid water
-life should be universal
Maraldi observed;
seasonal changes + changes in polar ice caps
what did they use to make detailed maps of mars?
Canali = channel/ canals
Wallace discovered what about Mars?
it’s not habitable and no life
what was the first flyby mission of Mars?
Mariner 4, NASA
what was the Viking biological experiments? (Mars)
1-Gas exchange
2-Pyrolitic release
3-labeled release
Mars pathfinder was what?
1st rover on planet other than Earth
MER 2004-
Mars exploration Rovers spirit and oppurtunity
the twin robotic geologists
Oppurtunity was sent to mars for what?
to find ancient liquid water
Evidence of oast water on mars?
-Remote sensing: Earth telescopes
river channels and valleys
lake basins
sedimentary minerals
-In situ: Rovers and landers
sedimentary rocks
aqueous alteration minerals (clay minerals..)
direct detection of water
-Mars meteorites
fluid inclusions in minerals
aqueous alteration minerals
what are 5 succesful landings on Mars?
-Viking 1
-Perseverance
-InSight
-Curiosity
-Oppurtunity
what planet did Mars look like 4 Ga?
earth
Was ancient Mars habitable?
curiosity found no life detection
what is gale crater?
5 km high mound of stratified rock -Mt. Sharp
What did they find on the Link?
conglomerate and sand
What is Shaler?
sandstone outside of Yellowknife
what is an Alluvial Fan?
a fan or cone shaped deposit of sediment built up by river streams
what did we use to observe mars?
spectroscopy -laser induced breakdown (LIBS)
what are the ancient habitiable environemtns in gale crater?
-Rivers, streams and lakes (3.5 Ga)
-Minerals in sedimentary rocks
-presence of compounds: CHNOPS
-Presence of organic carbon
-would have been chemical energy sources
what rover explored gale crater?
curiosity
Was there water in Gale Crater?
yes 3.7 Ga
Mars 2020:
mission objectives;
1-conduct rigorous in situ science and seek out potential biosignatures
2-collect and store samples for an eventual return to earth
what are the mars 2020 candidate landing sites?
Columbia Hills
Jezero Crater
why do we want to explore Jezero Crater?
-ancient lake filled crater
-rivers and major delta
-rocks minerals from microbial life
we hope to bring back soil and rocks back
why do we want a MARS sample return?
future instruments will get even better
signs of ancient microbial life
