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172 Cards in this Set

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Why is linear acceleration a concern when moving humans into space?
Leads to pooling in the lower parts of the body.
Decreased venous return and decreased blood pressure.
Affects ventilation in the lungs= less efficient gas transfer, reduced oxygen saturation of blood.
How can the effects of linear acceleration be minimized?
Restrict the magnitude of acceleration, by applying it to the +X direction, by using an anti-gravity suit, and by fluid loading before the onset on linear acceleration
Why is vibration a concern for moving humans into space?
Intense, low frequency vibration caused by engines and turbulent airflow can be dangerous if it contains significant energy near the resonant frequency of the human thorax
Even when it is not at this frequency, it can make it difficult to see instruments or reach controls
How can the effects of vibration be minimized?
By designing spacecraft to avoid dangerous frequencies, and automating launches so that crew members have a minimum of things to see or do during periods of significant vibration
Why is reduced atmospheric pressure a concern for space travel?
Amount of oxygen transported in blood starts to drop at reduced pressure, even if breathing pure oxygen
Hypoxia causes rapid loss of consciousness, without warning
Low atm can also cause decompression sickness (the bends)
How can the threat of hypoxia be eliminated when embarking on space travel?
By providing a normal mixture of breathing gases, at normal atmospheric pressure, inside some sort of pure vessel
Decompression sickness is avoided by washing out nitrogen prior to reducing the pressure
Why is weightlessness a concern for humans and space travel?
Prolonged weightlessness never experienced by humans until the advent of aircraft and spacecraft
Gravity has been the most stable environmental factor during human evolution and many body systems have had to take it into account, often in precise ways- prolonged weightlessness results in deconditioning of these systems
How can the effects of weightlessness be overcome?
In flight exercise, medications
Name six effects of space travel on the nervous system.
Motion sickness
Spatial disorientation
Gaze instability
Postural instability (after landing, strong tendency to orient towards the visual down)
Proprioceptive errors (loss sense of limb position= possible vehicle overcontrolling during reentry)
Motor control errors
Name three effects of space flight on the musculoskeletal system.
Skeletal muscle wasting (these muscles normally oppose gravity)
Back pain (expansion of intervertebral discs)
Bone demineralisation (normally oppose gravity, after long exposure get increased risk of fractures upon landing)
Name two effects of space flight on the cardiovascular system.
Cardiac muscle wasting
Loss of baroreceptor reflex (can cause fainting when gravity returns)
How does space travel effect the immune system?
Immunosuppression- cell mediated, may or may not decrease resistance to infection and tumours
What problems do extreme temperatures cause in space?
Astronauts working in space suits face overheating because of exposure to intense sunlight and physical exertion
May also risk frostbite of fingers because of extremely low temperatures in the shade
How are temperature issues in space overcome (for astronauts)?
Reflective clothing, thermal insulation, active heating and cooling garments
Tight heating and humidity control within the space station
Why is it hard to protect astronauts from radiation?
Shielding is not simple due to its weight and because it can create secondary neutrons and particles.
What problem does a closed environment play in space travel?
Food and water supplies must be carefully managed
Liquid and solid waste must be contained effectively, sterilised, and recycled
No off-gasing plastics, solvents, perfume, smoke allowed
Every piece of machinery must be 100% reliable (will take years to achieve this)
What are some psychological/interpersonal barriers to space travel?
Cabin fever (people go crazy)
Intercultural factors
How can one accelerate in space?
Solar thermal rockets
Nuclear thermal rockets
Chemical rockets
Ions engines
What is the principle of a rocket?
Need to dump mass as quickly as possible (conservation of momentum- if you loose mass, you will accelerate)
How do you measure the efficiency of a rocket?
Impulse= exhaust velocity/earth gravitational acceleration
Name two reasons space travel is expensive.
Multiusage rockets (inefficient)
Bureaucracy (costs $10 000-$20 000/kg of fuel...could buy the same amount of energy from Hydro Quebec for $1.80/kg)
Why would a carbon nanotube (buckytube) be good for constructing a space elevator?
Can support its own weight (theoretically) up to 40 000km in height
What is the equation for gravitational force?
F= G(Mm/r^2)
What is the equation for the centrifugal force
F=m(v^2/r)
For what kind of orbits are the gravitational and the centrifugal forces equal?
Circular orbits
The rate of area swept by the radial line is constant for what type of orbit?
Elliptical
What is the period (T) proportional to in elliptical orbits?
The cube of the semi major axis
What is the Hohmann transfer orbit?
The path that requires the smallest change in velocity from one orbit to another (the cheapest way to travel from one planet to the next)
Thus, in order to go to Mars, we would have to take the longest path
What is the departing velocity from Earth required to enter Mars?
32.7km/s
When using a transfer orbit to get to Mars, what happens between Earth and Mars? What must occur when the spacecraft arrives at Mars?
The spaceship will coast once it is outside of Earth's orbit
Once it arrives at Mars, it must slow down to catch Mars' orbit
What is the single most important limiting factor for lifeforms living on ice?
Availability of liquid water.
What are the north and northwest arctic achipelago classified as?
Polar desert (cold dry winters and cool summers, mean temp -15C)
how frequent are polar springs?
Springs in regions of thich, continuous permafrost are rare
What is unique about the thermal properties of polar springs?
Thermal and flow properties are remarkably constant given the harsh climate and extreme seasonal variations
How are the thermal properties or springs derived?
From a geothermal gradient
How can one characterise the abundance, distribution, and phylogenetic/physiological composition of microbial communities in springs and runoff areas?
Microscopy
Culture and culture independent approaches
Measuring environmental parameters (temp, pH, redox, oxygen, salinty)
Measuring specific physiological activities in situ (methanogenesis, sulfate reduction, denitrification)
What was the microbial life founf at the Axel Heiberg Perennial Spring like?
Psychotropic and salt tolerant
High homology with microorganisms found in polar regions
Bacteria were related to sulphur bacteria
Archaens were related to halobacteria
Name four fossil biosignatures that scientists look for.
Body fossils
Biominerals
Biofabrics
Stable isotopes
What was the original name for astrobiology?
Exobiology
When did NASA's involvement with astrobiology begin?
1957, after the conference on the Origins of Life on Earth in Moscow
What was the Viking mission? What was it's significance to astrobiology?
The Viking Mission occured in 1976, and consisted of two landers that went to Mars. They were not able to find life, and thus the field as astrobiology died for two decades
What is 51 Pegasi? What was it's significance?
The first extrasolar planet found
Found in 1995, revitalised NASAs astrobiology program
What two factors helped revitalise NASAs astrobiology program?
Discovery of 51 Pegasi and ALH84001
Name one problem with each definition of life: metabolic, thermodynamic, ability to reproduce
Metabolic: Difficult to exclude fire (grows and reproduces)
Thermodynamic: Difficulty excluding mineral crystals (sustain local order, reproduce)
Reproductive: Mules cannot reproduce, but they are alive
Name three ways that scientists search for life on other planets
In situ: send landers to planets/moons within our solar system
Spectral examination of planetary atmospheres
Searches for evidence of extraterrestrial technology
What are the three factors that our search for life (as we know it) is based upon?
Liquid water
A suite of "biogenic" elements
A usable source of energy
What properties does H bonding give water?
Water molecules stick together (cohesion)
H bonds break and reform frequently
At any given time, substantial portion of all molecules are bonded to their neighbours (gives water more structure than most other liquids)
Polar properties allow it to separate polar solute molecules
What problem would be created if water were replaced by methane/ethane for the formation of life?
Methane/ethane= non polar. Would require the use of polar substances to make membranes.
How has water contributed to Earth's habitability?
Stays a liquid over a wide range
Can dissolve almost anything given time
Absorbs heat slowly and holds onto it for a long time
Stabilises air temperature by absorbing heat from air that is warmer, then releasing the heat into air that is cooler
Can store a lot of energy for only a slight increase in temperature
Why was water-ice float?
As temp decreases, there is less energy to break H bonds, eventually all water molecules are H-bonded to one another forming a crysta lattice structre that is less dense than the liquid
Why is water called the universal solvent?
Due to its ability to form hydrogen bonds with polar solvents
What is the driving force of many biological processes (hint- not ATP).
The favourable disordering of water
What is a major difference between ammonia and water in terms of its ability to be used as a universal solvent?
Liquid at a lower temperature, thus biochemistry involving ammonia would proceed at a slower pace than terrestrial biochemistry
What are the six biogenic elements?
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
Potassium
What is a downside of silicon compared to carbon for its usage in life?
Does not readily form double bonds= less flexible
Many carbon based molecules found, not nearly as many silicon based molecules found
What are the two ways that organisms on Earth obtain energy?
Photosynthesis
Chemosynthesis
What is the galactic habitable zone?
The zone of our galaxy where intelligent life is mostly likely to be found
What are the three key parameters that define the galactic habitable zone?
Metallicity of the planet star
Nearby frequency of supernovae
Stellar age
What is metallicity? How does it affect habitability?
Metallicity= portion of a star that is made up of elements other than H and He
Increases towards the centre of the galaxy- therefore planet formation and solar system habitability should increase with decreasing galactic radius
Supernovae have an impact on habitable planets within what distance of their formation?
10 parsecs
Where are supernovae more likely to occur?
In the denser regions of the galaxy (galatic bulge, density fluctuations of the spiral arms)
What is the Circumstellar Habitable Zone?
Encompasses the range of distances from a star that liquid water can exist on a planetary surface
How many degrees warmer is the Earth than what it should be?
33K
What is the continuous habitable zone?
The region in which a planet may reside and maintain liquid water throughout most of a star's life (as stars like the Sun age, they dim)
What type of particle are electrons?
Leptons
What type of particle are protons and neutrons?
Quarks
How many fundamental particles of matter exist? What are the two main subdividions?
12
Quarks and Leptons
What is the nameof the force carrier particle
Boson
What are the four fundamental forces?
Gravity
Weak Nuclear Force
Strong Nuclear Force
Electromagnetic
What is the strong nuclear force?
The attractive force that binds neutrons and protons together in the cores of atoms and is a short range force (overwhelms the repulsion of protons from each other)
What is the waek nuclear force?
The force that causes B-decay
What is different about gravity compared to the other forces?
There is no quantum mechanical theory to describe it
What is the Grand Unified Theory
The idea that in the early universe, the Weak, Strong, and Electromagnetic forces were unified into a single force
What is the Superunifed Theory?
The idea that in the early universe, all four fundamental forces were a single force
Who first postulated the Big Bang Theory?
George Gamow
What did the universe arise from?
A singularity= where the curvature of space and time is infinite, possess zero volume and infinite density
What happened during the Planck Era?
0-10^-43 seconds of the Big Bang
Symmetry breaking of the early universe= phase changes
Decoupling of the gravitational force from the Superunified Force
What was inflation driven by?
The energy released from the phase transition when the strong force separated from the electroweak
What occured during the Quark Epoch?
The universe cooled enough for particles that are the building blocks of atoms (quarks and leptons) to form= quark soup
Universe created a little bit more matter than antimatter- this is why we can exist now
How many years have passed since the Big Bang?
13.7 billion
Name the three pieces of evidence for the Big Bang?
Expansion of the Universe
Cosmic Microwave Background Radiation
Relative abundance of light elements (H, D, He, Li)
How do we know that the universe if expanding?
Red-shift of distant stars. This means they are moving away from us
What would the spectrum of a star look like if the star were moving towards us?
It would be blue-shifted
What are the two implications fo Hubble's Law?
We are at the centre of the expansion of the universe
The universe is expanding equally everywhere= a property of spacetime
What is cosmic background radiation?
The afterglow of the big bang. the light has been stretched out so much now that it is in the form of microwaves.
What could possibly overcome the expansion of the Universe?
Gravitational attraction between the galaxies
What is critical density?
The mass density required for the gravitational pull of the universe to equal its kinetic energy
If mass density < critical density, what will happen?
The universe will expand forever
What is dark matter?
Matter that does not emit or reflect enough electromagnetic energy to be detected directly but whose presence can be inferred from its gravitational effects of visible matter
What is Omega(m)?
The mass density parameter. Includes contributions from normal and dark matter.
What are the four possible fates of the universe?
Recollapsing: expansion will halt and reverse ( omega>1)
Critical Universe: will not collapse, but will expand more slowly over time (omega=1)
Coasting universe: will expand forever without slowing down (omega<1)
Accelerating Universe: expansion will accelerate with time
The correct model= Accelerating Universe
What might be causing the universe expansion to accelerate?
Dark Energy- must be something that pervades space, provides and isotropic pressure that is non-local
What is Omega(t)?
The total density parameter. Includes mass (normal and dark) and energy (normal and dark).
Determines the geometry of the universe
What are the three possible geometric shapes of the universe?
(Wt=omega(t))
Wt>1= space is closed and positively curved (space would also contract)
Wt<1= saddle shaped
Wt=1 = flat
What is the Big Crunch?
The Big Bang in reverse
What is the Big Rip?
If dark energy increases with time, the universe may experience a catastrophic, runaway expansion. within 100 billion years every galaxy, star, and atom in the Universe would be ripped apart
In what kind of universie would the Big Rip occur?
An open universe. Means that the expansion of the universe must be accelerating.
What kind of universe does inflation predict?
A flat universe.
What is the geometry of our universe? What is its eventual fate?
Flat.
Will expand continuously. In 100 billion years, very few galaxies would be observable to us.
True or False: stars can be born in isolation?
False
What is the birth place of stars?
Molecular clouds (vast, cold, volumes of gas- H, He- that contain complex organic molecules)
How is interstellar dust created?
Produced in envelopes around red giants
In what form do stars begin their lives? How does this change over time?
Pure balls of hydrogen
Thermonuclear fusions begins, transforming H into other elements
How are stars classified?
In spectral types in order to decreasing mass and surface temperature
What type of star is our Sun?
G2 V star
5800K
How are high mass elements created?
In red giants, zones form. The elements with the highest mass end up at the core (Fe, Ni).
How do high mass starts convert H to He?
CNO cycle
What is the heaviest element created by stars?
Iron. Past this point fusion is not energetically favourable.
How are elements heavier than iron formed?
Bombardment of lighter elements by neutrons and protons.
Radioactive decay.
What are primary objects?
Stars
What are secondary objects?
Planets
What are tertiary objects?
Satelites
Where is the Kuiper Belt? What comes from here?
Belt of icy bodies in orbit beyond Neptune (Pluto is in this group).
This is the source of most periodic comets.
What are the two ice giants of the solar system?
Uranus and Neptune
True or False: all planets are in the same plane and orbit the Sun in the same direction.
True.
Describe the rocky planets.
Largely nickel-iron cores
Silicate rock mantles
What are the gas giants made from?
H, He, water, ammonia, methane and a rocky core
What are the two major types of theories about the formation of the solar system?
Catastrophic: accidental encounter between Sun and a star/comet
Non-catastrophic: natural event that may have occured in conjunction with the birth of a star
What are the facts that a model for the formation of the solar system must account for?
All the orbits are prograde
All the planets are in the same plane
There is a chemical gradation from the inner planets to the outer planets
Asteroid belt between Mars and Jupiter
Kuiper Belt
Oort cloud
Distances from Sun follow a simple arithmetic progression
What is the current dominant theory of planet formation?
Raw material in flattened disc
Disc hotter in centre and cooler on the outside
Planets formed from gravitational contracting- natural by products of the formation of a star
What three processes altered the shape, density, and temperature of the solar nebula?
Heating
Spinning
Flattening
What is the name of objects formed by accretion?
Planetisimals. They are the seeds for planet formation.
Gas in the solar system condenses after what point? What planets appear after this point?
Frost Line
Gas Giants
Why is it strange that Earth has water?
It accreted in the "dry" zone of the solar system
Why don't the terrestrial planets have abundant H and He?
Proximity to the Sun heats them and causes them to escape
How did the Earth form?
Grew by accreting planetisimals through gravitational attraction. This made Earth very hot and it partially/totally melted and the iron sunk to the core.
What is the Titus-Bode law?
The law that predicts the spacing of planets in the solar system.
Why was the moon vital to the formation of life on Earth?
Stabilised the tilt of Earth's rotation
Created tides
Why may tides have been important to the early formation of life?
Rapid changes in salinity could create DNA type molecules
What is the most favoured theory on the formation of the moon? What does it postulate?
Ejected Ring Theory
Planetisimal the size of Mars collided with Earth, ejecting matter
Disc of orbiting material formed, and condensed to become the Moon
When did the moon form?
100 million years after the solar nebula
50 million years after the accretion of Earth
What are the three primary layers of the Earth?
Crust
Mantle
Core
What are the two theories for the differentiation of the Early Earth?
Homogenous: Earth accreted with a homogenous density and composition
Inhomogenous: Earth formed without a prior homogenous state (core formed first, then came other layers)
What four events made the Early Earth super hot?
Accretion
Gravitational self compression
Differentiation
Decay of short lived radioisotopes
What are the two things required for a star or planet to generate a magnetic field?
Magnetic material
Currents
What creates Earth's magnetism?
Outer core (molten) spinning around inner core (solid)
What does the interplanetary debris complex consist of?
Small bodies including asteroids, comets, meteroids
Interplanetary dust particles
What are asteroids?
Dark, dense bodies orbiting in the inner solar system. Up to 1000km in diameter.
Where did comets form?
Beyond the frost line.
What is the nucleus of a comet?
The ice ball
What is the coma of a comet?
Cloud of water and carbon dioxide that forms when the nucleus of the comet gets close to the sun.
What are the two primary sources of comets?
Kuiper Belt
Oort Cloud
What types of comets arise from the Kuiper belt?
Short period comets
What types of comets arise from the Oort cloud?
Long period
What is a Meteroid?
Meteor?
Meteorite?
Meteroid: small body that originated from planet, asteroid, comet
Meteor: shooting star
Meteorite: when it lands on Earth
What are chondrites?
Stony meteorites with siliaceous material called chondrules and free metal
What are carbonaceous chondrites?
Stony meteoroids that contain organic compounds and water bearing minerals
What type of ice is good for looking for meteorites?
Blue ice
Where do interplanetary dust particles originate from?
Tails of Oort/Kuiper comets, collisions of small bodies
The atmosphere of Earth is of primary or secondary origin?
Secondary
What was the atmosphere of the early Earth composed of?
CO2 and N2
What gas makes up the largest portion of Mars and Venus atmosphere?
CO2
What are banded iron formations?
Sedimentary rocks consisting of repeated thin layers of iron oxides alternating with layers of iron poor shale
What is important about banded iron formations?
Tell scientists when oxygen arrived on Earth
Correction
Universe is saddle shaped and open
Fate of the universe- universe will rip apart
How does direct imaging of extrasolar planets work?
Planets reflect light from their parent star. Compare the luminosity ratio of the planet to the star
What is dynamical pertubation as it relates to finding exoplanets?
Orbiting planets affect the velocity and position of their parent star (wobbling)
What happens to the luminosity of a star when a planet crosses it?
It decreases. This is a way of detecting exoplanets.
How does the detection of exoplanets using gravitational microlensing work?
Apparent brightness of a star can be amplified by the gravitational field of a star-planet lensing pair moving across the line of sight.
What type of detection is good for high mass planets at long distances from their planet star?
Direct Imaging
What types of detection are good for high mass planets at short distances from their planet star?
Radial velocity
Astrometry
Planetary transit
Microlensing
What types of detection are good for finding low mass planets close to their star?
Pulsar timing
Planetary transit
What can radial curve velocity tell us about an exoplanet?
Orbital period
Average distance from parent star
Shape of the orbit
Minimum mass of the planet
What are most exoplanets discovered so far like?
Massive and close to their stars
What is orbital migration? Why is it important?
Orbital migration is what occurs to some exoplanets- they get closer to their stars. This prevents small rocky worlds from forming.
There is a strong correlation between ____ in a star and having one or more planets?
Abundance of heavy metals
What are polycyclic aromatic hydrocarbons?
Complex networks of benzene rings
Make up 10-15% of galactic carbon
What two phenomena can create large quantities of organics?
Meteorite shocks
Reducing atmospheres
What gases did Miller use?
Ammonia
Methane
Water
Hydrogen
Explain the iron-sulphur world theory.
Early chemistry of life took place of mineral surfaces, not oceans
First cells were lipid bubbles on mineral surfaces
Pyrite served as a source of reducing power
Describe the clay mineral theory on the origin of life.
Clay minerals have a complex crystalline structure with a complex pattern of positive and negative charges
Clay minerals can "grow" by adding new atoms while maintaining the crystal structure
Lattice structure may have acted as template for polymers
What evidence indicates the clay hypothesis is wrong?
Aluminum and silicate should be more common in biology if it were true