M&P Exam 02 Flashcards
(105 cards)
1
Q
What are the 3 main theories of moon formation? What bodies are associated with each?
A
Collision: Mars moons & Earth’s moon
Accretion: Jupiter’s moons
Capture: thought mars moons
2
Q
How does accretion theory explain the formation of larger Jovian moons?
A
Dust & ice clumps spiral toward the young planet to form a disk around it with spiral density waves & satellitesimals that collect more material until they are stable moons.
Io & Europa formed in 6,000 years, callisto in 9 million years
3
Q
Why do eccentric orbits slow down in accretion?
A
Orbits faster at perihelion & slower at aphelion
4
Q
What problems were there in the belief that Mars’ moons were captured from solar orbits? Why is it unlikely?
A
Circular orbits & lack of second force to reduce their kinetic energy
Martian atmosphere could not have been tall enough to slow them down
Probability of other gravities being just right is very low
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5
Q
What do simulations suggest about the formation of Mars’ moons?
A
Collisional formation
6
Q
How was Earth’s moon formed?
A
Originally thought to be formed by accretion, but moon rocks indicate oxygen isotope abundances identical to earth rocks.
Lunar chemistry identical to earth’s chemistry
Impact Theory
Because of tides, moon’s orbital radius increases 38mm/yr
7
Q
What causes the moon’s rotation period to match its orbital period?
A
Perturbation force that tugs harder on near side caused rotation period to equal the orbital period (synchronous rotation) & mascons on near side
8
Q
What did the Grail Spacecraft look for? How?
A
Map local gravity strength using the distance between 2 probes, Ebb & Flow
Both satellites in same orbit, when 1 enters stronger gravity, it speed up
Laser measures distance between them & from gravity map, local lower density crust thickness can be calculates & then actual sizes of sub-mare craters
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9
Q
How do the near and far side of the moon compare? Why is the far side cratered?
A
Lunar Prospector mission
Near side crust is 50km thinner
Radioactive Uranium & Thorium heated near side surface more (nucleosynthesis of thorium)
Higher surface gravity on near side under high density maria
10
Q
What is significant about the Maria?
A
Large early impacts caused circular fractures in moon’s crust
Increased thermonuclear crust heating on the near side > lava flowed through cracks > cooled to form maria
11
Q
What is the moon’s escape velocity?
A
2.4km/s = minimum impact velocity
12
Q
What is the Sister Splash Theory?
A
Lunar collision with an early sister moon in orbit that got disturbed & collided at minimum impact velocity.
More low density crustal material deposited on far side
Thinner crust on near side caused mascons that led to synchronous rotation
13
Q
How did the sister moon form?
A
At L4 or L5 of brother moon
Earth’s tides destabilize orbit & sister drifted away from its L point & they collide at minimum impact velocity
Sister formed at L5, decrease period… if formed at L4, increase period
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14
Q
What solutions are there to the Sister Splash Theory?
A
Chemical analysis of Apollo lunar rocks on near side
Issues with communication on far side
15
Q
Facts about IO
A
Larger than our moon
Orbital period = 42 hours
Phase-locked rotation
SO2 ice surface
Orbit synchronized to 2 other moons
16
Q
Why are there active volcanoes on io?
A
Friction is generated when close to other moons & gravitational warping, causing orbital tidal distortions that cause magma heating.
This produces lava lakes and plumes of SO2.
17
Q
Facts about Europa
A
Smaller than our moon
3.52 day orbital period
Phase-locked rotation
Water-ice Surface
Tidal Flexing => Heating caused by resonances with io & ganymede
18
Q
Why do we think there is more water on Europa than on Earth?
A
Galileo Probe found evidence of subsurface ocean
Magnetic field fluctuates, suggesting mantle is electrically conducting & shifting due to briny water
Ice surface is shape-shifting => liquid beneath
Flew through a water plumes
19
Q
What are Chaos Zones on Europa?
A
Dark, circular shapes caused by warm subsurface lakes & glacial flow to the surface
Liquid water cools & freezes, expanding causing the surface to crack. Water rises and collapses as ice
Possibly points of concentrated tidal heating
Lenticulae
20
Q
What are Plumes on Europa?
A
Produced by fissures/cracks caused by pressure & shoot out ice
Location correlates with hot spots & contain H2O
21
Q
What do ice fractures & impact cratering show on Europa?
A
Spectral line analysis shows they contain magnesium sulfate (Epsom Salt)
Few craters means surface is young (4-6 mil years old)
22
Q
Describe Europa’s interior
A
20 km ice
80 km briny ocean
Rocky body & iron core
23
Q
Describe the life sustaining “Black Smokers” on Europa
A
Hydrothermal vents on Earth spew heat & chemical nutrients caused by heat reservoirs below the ocean floor – perhaps necessary for life
24
Q
What does the Europa Clipper Mission aim to observe?
A
Arrive in 2030 to investigate the interior of Europa from orbit by radar
Analyze ocean & ice shell, geology, composition
REASON: ice penetrating radar to tell us about water under ice
25
What will JUICE (Jupiter Ice Moons Explorer) Explore?
Characterize ocean layers & subsurface water, mass distribution, Ganymede atmosphere & magnetic field, interactions with Jovian magnetosphere
26
Facts about Ganymede
Largest moon in solar system
Ice covered surface
Dark areas older, lighter regions younger with organics due to impactors
27
What did Hubble Image on Ganymede?
Auroral belts & magnetic field that move over time => subsurface ocean
Perhaps suggest water vapor in the atmosphere
28
Facts about Callisto
Larger than our moon
Ice surface
Orbit not synchronized or tidally heated
29
Why can’t Mars support liquid water today?
Not enough atmospheric pressure to maintain liquid state
30
Describe the water phase diagram
Pressure & temperature axes
Triple point: point at a certain temperature and pressure where a substance can be in any 3 phases
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31
Why do ice skates glide?
Old Theory: blade pressure lowers freezing point => liquid layer, but freezing temperature is too high (31.9 F)
New Theory: Ice has a semi liquid outer layer & every 3rd molecule vibrates vertically. In ordinary ice, all water molecules are bound solid
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32
Draw Mars on the Phase Diagram
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33
Describe why there is no liquid CO2 on Mars
Liquid CO2 needs 5.1 atm at any T, neither Earth nor Mars has enough pressure
CO2 sublimates on Mars (solid to vapor) at a lower temperature than water, so permanent parts of polar ice caps and frost are water ice
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34
What evidence is there for ANCIENT liquid rocks on Mars?
Orbital photos of dry rivers & lakes (wake islands from water flow)
Hematite Crystals (blueberry rocks)
- Iron oxide in mineral form that crystallizes in aqueous solutions over 1,000 years
Layered terrain may be sedimentary (water flows & dumps mud)
Meteorites from Mars show signs of liquid erosion
- High energy impact ejects it from Mars & orbit around sun & collide with Earth
- Infused with water
35
What evidence is there for liquid water on Mars TODAY?
Martian Gullies of sandy soil
- No impact craters or wind blown erosion = young
- Dark rivulets = signs of water
- Aquifer source ~100 m down… sand puts enough pressure to have water in liquid state in a semi-permeable layer. Water evaporates at surface but it replenished
- Changes seen in gullies (falling sand)
36
How could Mars have had liquid oceans?
Need regions of pressure > 0.006 with temp > 0.01 C
Atmosphere must have had higher pressure
37
How do we know Mars had a thicker atmosphere?
NASA & U Colorado MAVEN (Mars Atmosphere & Volatile Evolution Probe)
- Determine how Mars lost its atmosphere & sample it
- Probe had 33 burn to slow it down & got captured into elliptical orbit, passes through upper atmosphere to sample every 4.5 hrs until it lost speed
38
What does it mean when a gas is “bottom up”?
Gas is absorbed into ground
Heavier isotopes sink in atmosphere so they escape less
39
What does it mean when a gas is “top down”?
Gas escapes from exosphere
2013 Curiosity indicated heavier isotopes are abundant on Mars
40
What are some “top down” models? How do gas molecules escape?
Model 1: Neutral Processes
- H gas in Martian atmosphere escapes
- H2 comes from dissociation of water in atmosphere, so water is depleted
- MAVEN: H escapes, O does not
Model 2: Solar Wind Stripping
- Solar UV ionizes upper atmosphere atoms & solar wind carries atoms away
- Mars has little atmosphere, so its ionosphere deflects ions, slowing solar wind stripping
- MAVEN: measured solar wind particles deep in Mars’ atmosphere… atoms may be combining above the ionosphere into neutral particles, then reionizing to carry away ions.
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41
What is the Martian Plume?
Plume of hot mantle material rising to lift the surface & causing volcanoes, so Mars is more active than we thought.
Methane, CO2, O2, H2O.
42
State 2 major differences between near and far sides of the moon.
Radioactive Uranium & Thorium heated near side more and its crust is 50km thinner than the far side… caused mascons/maria.
Far side less cratered & has low density crustal material that was deposited by collision with sister moon.
43
Describe how lava was heated and got to the moon’s surface to form the maria.
Large impacts caused circular fractures in moon’s crust
Increased thermonuclear crust heating on the near side => lava flowed up through cracks which cooled to form the smooth maria.
44
Describe 3 different reasons we think Europa has a liquid ocean under its ice crust.
2016: Hubbled discovered plumes of water
1990 Galileo probe measured fluctuation of magnetic field, suggesting the mantle is electrically conducting & shifting (briny water) & ice surface is shapeshifting (liquid beneath) & flew through water plume
Chaos zones caused by warm subsurface lakes and glacial flow to the surface… possibly points of concentrated tidal heating.
45
Write Earth, Earth’s moon, Mercury, Europa, Ganymede & Callisto in a row with their diameters decreasing towards the right.
Earth: 7,926.2 mi
Ganymede: 3,267.7 mi
Mercury: 3,031.9 mi
Callisto: 2,995.4 mi
Earth’s Moon: 2,159.1 mi
Europa: 1,937.7 mi
46
An exoplanet has a pure CO2 surface at 0C temperature on the night side. At about what atmospheric pressures will the surface melt & boil?
CO2 can only exist as a liquid at 5.1 atm.
47
State 3 different kinds of evidence for ancient liquid water on the Martian surface. For 2 of them, including the decade the evidence was first collected.
1970s: Orbital photos of dry rivers and lakes from Mariner/Viking
2004: Hematite Crystals (blueberry rocks)... iron oxide in mineral form that crystallizes in aqueous solutions
2006: layered terrain may be sedimentary
Meteorites from Mars show signs of liquid erosion
48
Titan Facts
2nd largest Saturn moon
Appeared brighter after passing through Saturn’s shadow, assumed atmosphere was condensing and freezing
Occults a double star
Orbital period = 15.9 days
Phase-locked to Saturn… Saturn year is ~29 Earth years
Axial tilt = 27°
Strong winds
Titan Day = 15 Earth days
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49
When & How Did We Get First Measurement of Titan’s Atmospheric Pressure?
1980 Voyager 1 Flyby – Signal Attenuation: 1st atmospheric pressure measurement
Surface Pressure > 2.6 bars
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50
Should Titan Have an Atmosphere?
Plot temperature & Escape Velocity
Distance from Sun, D = 9.5 AU
Mass, M = 1.3x10^23 kg
Radius, R = 2.6x10^6 m
Escape Velocity (sqrt(2GM/R) = 2.6km/sec
Surface Temperature: ratio to Earth
- Assume Titan has similar albedo & greenhouse to Earth
- Titan 9.5x further from Sun, ratio solar energy flux (fT/fE) = 1/9.5^2 = (0.011)^¼ = 0.32… flux in/out prop to T^4
TT = 290 (avg Earth temp) x 0.32 = 93k
- Titan keeps CO2 & O2 (barely)
Methane can be solid, liquid, or gas
T = 93k
P = 1.5 bars
51
How Do We Know There are Methane Lakes?
Surface Mapping...
Cassini mapped Titan’s surface by radar at a low angle
- Smooth surface = no return (black)
- Rough surface = diffuse radio echoes (bright)
- Height & depth determined by echo time
Channels, networks, clouds indicated methane rainfall & evaporation
Few impact craters = rapid erosion
Ice terrain
Troposphere clouds of methane & ethane form similarly to Earth
Huygens findings indicate periodical liquid methane rainfall & other organics
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52
Titan Atmosphere Facts
98.4% nitrogen, remainder methane & hydrogen
Lower gravity = atmosphere more extended
Sun should have converted methane to hydrocarbons
53
Theoretically, what would life be if methane is abundant?
Life would be methane based, oxygen free
Theoretical methane based membrane: azotosome might be made of nitrogen, carbon, & hydrogen molecules
Acrylonite, colorless liquid in atmosphere
Creatures inhale H2, react it with acetylene => methane
- Evidence: larger concentration of H2 in upper atmosphere & lower levels acetylene near surface
54
Enceladus Facts
6th largest moon
In E ring, suggests it is the source of ring material
500km diameter
Tidally locked
Frozen water surface
tectonics/resurfacing, overlapping features, little raters. Sharp features
55
What are the Sulci of the South Polar Region of Enceladus?
Alexandria, Cairo, Baghdad, Damascus
Warmer, fresh ice – 180k, 72k surrounding
Heat generated & lost 10x what was expected
Water plumes
56
Libations on Enceladus
Surface wobbles, suggest briny water below to prevent freezing
Ice crust, global ocean, rocky core. Active jets in south polar region
57
What did 2005 Cassini Find?
Plumes from Sulci, spectra indicated they are mostly water
Detection of N2 suggests hot interior likely formed from heated ammonia similar to hydrothermal vents
58
What are Possible Sources & Problems of Internal Heat?
Tidal from Saturn, but eccentricity 0.0047
Tidal from Dione resonance likely
Radioactive Decay, not enough
Hot original Core, too small
59
What is the Saturn E Ring?
Composed of water ice from Enceladus’ plumes
Composed of ammonia & silicate compounds
Indicate internal chemistry
Organic compounds
60
Pluto Facts
Mass = 1.31x10^22 kg
Surface Gravity = 2.2 ft/s^2
Surface Temperature = -385 F
Plains: 98% nitrogen ice, traces of methane, carbon dioxide
61
Who Discovered / Why was Pluto Discovered?
Percival Lowell at Lowell
Observatory used to observe Mars
1905 Lowell & Harvard Observatory measured deviations in Neptune’s orbit (turns out there were none)
- Attributed to perturbation forces
- Predicted position of the new planet
62
How Did They Find Pluto?
Blink Comparator: smaller than predicted
Flips mirror back and forth between beams from 2 microscopes to compare 2 photographic plates
63
How Do We Measure a Planet’s Mass?
Orbital motion of moon around it
Smaller than our moon
High eccentricity & inclination angle
1930: Jupiter Mass or more – so big due to Neptune’s orbit
1931: 1 Earth Mass – too dim to be big
1978: 0.002 Earth mass – drop due to discovering Charon
64
Why will Pluto & Neptune Not Collide?
Orbits are synchronized (3:2)
Do not cross in 3D space
65
Describe Charon’s Discovery
1978 James Christy
Thought to be binary planet
with Pluto
Mass Ratio = 0.17
5 Pluto Moons
66
What did New Horizons Do?
Mapped Pluto’s atmosphere & Surface, studied its moons
Closest approach 2015
Brightness mapped by transits of Charon
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67
Facts About Pluto’s Atmosphere
Nitrogen rich, replenished by internal radioactive heat source
Taller than Earth’s: 1,000 mi high
“Dark Fields” in dunes show movement of surface material, indicating wind movement
- North Polar Region => thin surface deposit, frozen methane from Pluto’s atmosphere
Colors represent different surface ice
68
Facts About Pluto’s Surface
Water, methane, & nitrogen ice mountains harder than rock formed ~100 mil years ago & geologically active
“Tombaugh Reggio” heart shaped feature
Mountains up to 11,000 ft
Few craters = young surface
Cliffs/troughs 600 mi => widespread crust fracturing
Circumferential fracture = collision => Charon origin?
Sputnik Planitia (“the heart”) faces away from Charon
Surface fractures hint at possible subsurface ocean freezing slowly
69
Other Pluto Moons
Hydra: irregular shape & size, water ice surface
Kerberos: smaller & thought to be formed by 2 objects that fused
Nix: not spherical, cleaner ice than Charon & reflects more light
70
Draw 2 diagrams showing how the Cassini craft could distinguish liquid from solid surfaces on Titan.
Cassini mapped Titan surface by radar at a low angle
Smooth surface make no return => shows black
Rough surface diffuse radio echoes => shows brightly
Height & depth determined by echo time
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71
State the reasons why we think Enceladus has a warm interior, and the most likely process we think is keeping it warm.
Cassini IR mapping shows heat around sulci
Librations (surface wobbles) suggest water below that is probably briny to prevent freezing
Cassini photos show plumes from sulci
Detection of N2 from Cassini flyby formed from heated ammonia
E ring composed of water ice from plumes
Most likely process is heating from plumes formed by heated ammonia similar to hydrothermal vents
72
State 4 ways in which Pluto and/or its orbit are different from the solar system planets.
Pluto has a very small mass 1.3x10^22 kg
Smaller than our moon
High eccentricity
High inclination angle
Orbit synchronized with Neptune & cannot cross 3D space
Atmosphere taller than Earth’s
73
Describe how we discovered Charon, and state 2 facts that make it unusual compared to all the other solar system moons.
Discovered Charon as a companion (thought to be binary planet) because of a bulge in photographs of Pluto
Large mass ratio = 0.117 (largest satellite relative to parent body)
Mutually tidally locked (same surfaces always face each other)
74
What are lagrange points?
5 lagrange points
Equilibrium locations where the combined gravitational forces of the 2 bodies create a stable orbit
Object at lagrange points orbit with same period as other body
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75
Energy Balance at Lagrange Points
Derive total energy, E: K (kinetic energy) + U (gravitational potential energy)
- E = 0 ; forces balance, inward & outward forces are equal => Equilibrium
- E slopes down in all directions & small deviations return to equilibrium => Stable Equilibrium (L4 & L5)
Force difference decreases with distance
L1, L2, L3: Unstable Equilibrium
76
Kepler’s 3rd Law & L2
Mp^2 α a^2
Larger orbit => Longer period
Larger M => Shorter period
Earth adds slight mass to shorten orbit to have same orbital period
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77
Kepler’s 3rd Law & L1
Smaller orbit => shorter period
Less M => longer period
Earth subtracts mass to lengthen orbit
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78
Forces at L2
Find R: E << M , r = (R-r)(E/3M)^⅓ = 1.5x10^9m
Find p: p = 2piR/v = 365.3 days
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79
Where is L2?
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80
L4 & L5
Located on Earth’s orbit, which orbits Earth/Sun barycenter & its orbital period depends on that radius
Adjust to have same R as Earth/Sun barycenter: L4 increase period, L5 decrease period
L4 & L5 equal distances at 60 degrees
Gravitational forces shift tidal force & barycenter distance α to mass
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81
What are Halo Orbits? Problem?
Objects that do not need to be exactly at lagrange points, but can orbit around them & are maintained by combined gravitational forces of the 2 main bodies
Problem: orbit must be tilted due to the sum of solar and halo orbit velocities.
A greater v on top means you need a smaller orbit to reach equilibrium
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82
Halo Orbit Stability
Elliptical halo orbits are not stable in systems with more than 2 bodies, need Lissajous orbits with course corrections
83
Examples of Lagrange & Halo Orbits
2001 WMAP (L2)
- Measured graininess of cmb
- Needed halo orbit to observe away from sun, earth, and mars to compare opposite directions
1978 ISEE 3 (L1)
- Study solar effects on earth & combined data with ISEE 1 & 2
84
Why are Earth-Moon Lagrange Points Important?
L2 (far side): maintain constant communication with far side of the moon 1960s
85
With 2 brief equations or sentences, explain why the L3 point of the Sun/Earth system must be outside Earth’s orbit?
The sun is also affected by Earth's gravity & orbits around the barycenter.
The point is located on the opposite side of the Sun & feels Earth's gravity adding, so it orbits further from barycenter to have the same 1 year orbit.
86
With 2 brief sentences or equations, explain why the plane of halo orbits around the Sun/Earth’s L2 are not perpendicular to Earth’s orbital plane.
The orbit must be tilted due to the sum of solar and halo orbit velocities.
Greater v at the top means you need a smaller orbit to reach equilibrium.
87
Asteroid vs. Meteoroid
Asteroid: irregularly shaped rocky body orbiting the sun that is not a planet or dwarf planet
Meteoroid: Solid object moving in space smaller than an asteroid & larger than an atom
Meteoroid: small particle from a comet or asteroid orbiting the sun
Meteor: fireball event when one enters atmosphere
Meteorite: on the ground or water
Bolide: very bright meteor
Over 1-2 km = worldwide effects (every 1-2 mil years)
88
What is airburst energy?
How much energy is released if it explodes in the upper atmosphere
20-30m = danger point… likely to penetrate the atmosphere & hit the ground (every century)
57MT Impact Energy
89
Name major meteor & asteroid events.
1908 Tunguska Meteor (Siberia)
- Airburst = 10-15 MT
- Projectile ~75m diameter
1947 Sikhote-Alin Meteor (Russia)
- Airburst = 10kt
- Mass = 100,000 kg = 2.5m diameter
2013 Chelyabinsk (Russia)
- Airburst = 400kt
- Mass 11 mil kg = 19m diameter
- Damage from shockwave
Chicxulub Crater (66 mil years ago)
- 150 km diameter
- Impactor = 10km diameter
- 100 tetratons TNT
- Origin of K-T boundary (dinosaur extinction)
Meteor Crater Barringer (0.04 Ma)
- Impactor = 50m
Toutatis: largest known potentially hazardous asteroid
90
Explain the Trojan Asteroids at L4 & L5
Orbiting Jupiter L4 at 60°
Hildas in resonant orbits and are gravitationally affected by Trojans & migrate from 1 Trojan orbit to another
91
Explain gravity assists.
Accelerate/decelerate, change inclination/direction of orbits
Add velocity
Jupiter-Centric
- Gravity gets weaker as it goes out & straightens – too fast to orbit
Sun-Centric
- Add planet’s orbital velocity throughout
92
What is the astrometric method of exoplanet detection? What star did it find?
Seeing a star’s apparent wobble due to planets
Bernard’s Runaway Star: see its apparent rapid movement
- M type red dwarf => 0.35% sun’s luminosity
93
What is geometric parallax?
The further the star, the smaller the angle p
Rpcs = 1/p”
Star has its own proper motion moving across the sky
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94
Describe Peter van de Kamp’s exoplanet detection and its issues.
1963: detected 2msec wiggle in Bernard’s path & discovered exoplanet orbiting it from 2,413 photo plates
- Planet period = 24 years
- mass = 16 Jupiter masses
- Proper motion = 10 sec arc/yr
1969: 2 exoplanets
- Period = 12 & 26 years
- Mass 0.8 & 1.1 Jupiter masses, 0.05 sec/arc deviation
1970s-1990s: Hubble saw no wiggle
1972: Heintz found that periodic irregularities were due to cleaning primary lens
2013: no evidence for Bernard’s star planets based on doppler shift (until March 2025 where 4 were confirmed)
95
How do we detect exoplanets today?
Transit
Doppler
Microlensing
Pulsar Period Doppler
Direct Imaging
Schlieren Photography
96
Describe the transit method & its problems.
Best for smaller orbits & bigger stars
Star periodically dims as planet passes in front, yielding period of orbit, p
% dimming yields ratio of radii => planet radius
Period + star mass = planet orbit size
Problems:
- Orbit must be seen edge on
- False readings due to stellar luminosity fluctuations
- Get planet radius, not mass
- Only works for large planets
- Star dimming hard to measure
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97
Describe the Doppler method & its problems.
Best for further & massive planets
Doppler shift of star yields orbital period & velocity due to a planet orbiting
Determine planet mass, m: - - 2piR = vp (solve for star orbit radius), use kepler’s 3rd to get planet orbit radius
Problems:
- Orbit is inclined at unknown angle
- Cannot get radius
- Rotation of star broadens spectral lines
- Distant star spectra faint
- Large orbits => little star movement
- Cannot yield angle of inclination
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98
Describe microlensing & its problems.
Best for massive planets
A background source appears brighter when a star passes through our line of sight due to gravitational lensing - can increase due to planet’s mass
Problems:
- Alignment must be perfect & it never repeats
99
Describe pulsar period doppler shifts & its problems.
Best for further & massive planets
Pulses travel different distances to reach Earth & observed pulse period is lengthened when pulsar is receding
Pulsar velocity is 10 m/s due to planet orbit
Shift in period is greater than pulse stability
Problems:
- Pulsar planets should be rare
- Inclination angle
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100
Describe direct imaging.
Best for further & bigger stars.
Block star’s light with coronograph
101
Describe Schlieren Photography.
Modulate air between 2 lenses & add knife-edge block at focal point
Record image of modulated air volume formed by second lens
Camera records darkened pattern of air turbulence
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102
Draw circles representing the sizes of the 3 largest meteoroids seen by humans to pass through the atmosphere in the last 150 years. Label each with the name given to it, but numbers are not needed. Also state how the biggest one compares in size to the Chicxulub impactor.
Tunguska Meteor = 75m
Sikhote-Alin = 2.5m
Chelyabinsk = 19m & airburst 400kt => Chicxulub crater = 150km (150000m) & 100 tetratons, Chicxulub is 7895x Chelyabinsk.
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103
Draw 1 or 2 diagrams showing how the gravitational assist of a spacecraft by a planet can reduce the spacecraft’s heliocentric velocity.
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104
Exoplanet “b” has 0.5% the radius of its parent star. Show why the Kepler satellite could or could not have detected it, assuming it has the right orbit orientation and position in space.
ᇫL/L = (Rp/R*)^2
(Rp/R*)^2 = 0.005
ᇫL/L = (0.005)^2 = 0.000025 = 25ppm
Could detect under ideal conditions (not much atmospheric turbulence)
105
State which method of exoplanet detection is best and which is worst for finding exoplanets with orbits larger than Saturn, and explain why for each.
Very large orbit
Best is Direct Imaging = Further & Bigger
Worst is Transit = Small orbit & big stars
Doppler = Further & massive planets
Microlensing = Massive Planets
Pulsar Period Doppler = Further, massive planets
