astronomy 101 the solar system tuesday, wednesday...
TRANSCRIPT
Astronomy 101The Solar System
Tuesday, Wednesday, Thursday
Astronomy 101The Solar System
Tuesday, Wednesday, Thursday
Remaining Schedule
• Today – Quiz; Meteorites, Mercury, and Venus• Wednesday - Presentations• Thursday - Mars• Thursday - Mars• Tuesday – Last quiz; Optional final; Final presentation
Remaining Schedule
Quiz; Meteorites, Mercury, and VenusPresentations
Last quiz; Optional final; Final presentation
What are meteorites?What are meteorites?
Meteorite
• A small extraterrestrial body that reaches the Earth's surface
Meteorite
A small extraterrestrial body that reaches the Earth's
Why are meteorites important?Why are meteorites important?
Why are meteorites important?
• They are primarily fragments of asteroids, which can hit us
• They are records of the early solar system• They are records of the early solar system
Why are meteorites important?
They are primarily fragments of asteroids, which
They are records of the early solar systemThey are records of the early solar system
MoonMoon
Meteorites
• Usually have ages of ~4.6 billion years• Asteroids and comets are thought to be the
building blocks of the terrestrial planetsbuilding blocks of the terrestrial planets
Meteorites
Usually have ages of ~4.6 billion yearsAsteroids and comets are thought to be the building blocks of the terrestrial planetsbuilding blocks of the terrestrial planets
Meteorites
• Many early cultures recognized (or believed) certain stones as having fallen from the sky
• Many early cultures had tools made from iron • Many early cultures had tools made from iron meteorites
• But to the scientists of the Renaissance and later periods, stones falling from the heavens were considered superstition or heresy
Meteorites
Many early cultures recognized (or believed) certain stones as having fallen from the skyMany early cultures had tools made from iron Many early cultures had tools made from iron
But to the scientists of the Renaissance and later periods, stones falling from the heavens were considered superstition or heresy
More evidence …
• In 1492, a meteorite weighing almost 130 kilograms landed near the town of Ensisheim, Alsace, France, then in the hands of GermanyAlsace, France, then in the hands of Germany
More evidence …
In 1492, a meteorite weighing almost 130 kilograms landed near the town of Ensisheim, Alsace, France, then in the hands of GermanyAlsace, France, then in the hands of Germany
Then ..
• In 1794, Ernst Friedrich Chladni, considered the father of meteoritics, published a book in which he concluded that stone and iron masses did fall he concluded that stone and iron masses did fall out of the sky
• In 1803, thousands of meteorite fragments bombarded L'Aigle in Normandy, France, an event investigated by JeanFrench Academy of Science.
Then ..
In 1794, Ernst Friedrich Chladni, considered the father of meteoritics, published a book in which he concluded that stone and iron masses did fall he concluded that stone and iron masses did fall
In 1803, thousands of meteorite fragments bombarded L'Aigle in Normandy, France, an event investigated by Jean-Baptiste Biot of the French Academy of Science.
Thomas Jefferson
• Meteorite landed in Weston, CT• It was brought to Yale where it was concluded it
was from outer spacewas from outer space• Thomas Jefferson, President of the United states,
was told about it
Thomas Jefferson
Meteorite landed in Weston, CTIt was brought to Yale where it was concluded it
Thomas Jefferson, President of the United states,
And responded
• "Gentlemen, I would rather believe that two Yankee professors would lie than believe that stones fall from heaven."stones fall from heaven."
And responded
"Gentlemen, I would rather believe that two Yankee professors would lie than believe that stones fall from heaven."stones fall from heaven."
Meteorites
• Named after a nearby geographic locality
Meteorites
Named after a nearby geographic locality
Meteorite
• Esquel Pallasite• Found in Esquel, Argentina
Meteorite
Found in Esquel, Argentina
Meteorites
• Almost all are thought to be fragments of asteroids• Where else can they come from?
Meteorites
Almost all are thought to be fragments of asteroidsWhere else can they come from?
Meteorites
• Almost all are thought to be fragments of asteroids• Where else can they come from?
– Moon - ~68 samples– Moon - ~68 samples– Mars - ~34 samples– Comets?– Venus?– Mercury?– Other solar systems?
Meteorites
Almost all are thought to be fragments of asteroidsWhere else can they come from?
Peekskill Meteorite
• http://aquarid.physics.uwo.ca/~pbrown/Videos/peekskill.htmhttp://aquarid.physics.uwo.ca/~pbrown/Videos/peekskill.htm
Meteorites
• Meteorites are composed of different minerals– Silicates – contain silicon and oxygen– Sulfides – contain sulfur– Sulfides – contain sulfur– Oxide – contains oxygen– Iron-nickel metal
Meteorites
Meteorites are composed of different mineralscontain silicon and oxygen
contains oxygen
Meteorites
• Usually named after the town (or nearest town) where they fell or were located
Meteorites
Usually named after the town (or nearest town) where they fell or were located
Falls and Finds
• Falls – see them fall• Finds – find them
Falls and Finds
Fall Statistics (greater than 1%)• Meteorite type Fall Percentages• L chondrites• H chondrites• LL chondrites• Irons• Irons• Eucrites• Howardites• CM• Diogenites• Aubrites
Fall Statistics (greater than 1%)Fall Percentages
38.0%34.1%7.9%4.2%4.2%2.7%2.1%1.7%1.2%1.0%
Where is the best place to find meteorites on Earth?Where is the best place to find meteorites on Earth?
Where is the best place to find meteorites on Earth?
• Antarctica• Deserts
– Sahara
Where is the best place to find meteorites on Earth?
Antarctic Meteorites• Designation for which ice field
they were found• ALH Allan Hills
EET Elephant MoraineEET Elephant MoraineLEW Lewis Cliff
• Then year and then number (which gives order of discovery)
• For example, ALH 84001 was first meteorite discovered in 1984field season
Antarctic MeteoritesDesignation for which ice field
Then year and then number (which gives order of discovery)For example, ALH 84001 was first meteorite discovered in 1984-1985
How do you know a rock is a meteorite?• Some possible indicators• Presence of Iron-Nickel (FeNi) Metal• Density• Magnetism• Presence of Chondrules• Fusion Crust• Fusion Crust• Regmaglypts
– Ablation of meteoritewhile passing throughatmosphere
How do you know a rock is a meteorite?
(FeNi) Metal
Meteor-• For example, magnetite (Fe
has grey streak • The best test is finding
Ni in the metallic iron
-wrongsFor example, magnetite (Fe3O4) is magnetic, but
• NWA 736 (H3.7) NWA stands for North West Africa• Hassayampa (H4)• Pultusk (H5)• NWA 869 (L5)• Holbrook (L6)• Long Island (L6)• NWA 2040 (LL3.5)• NWA 1584 (LL5)• NWA 852 (CR2)• NWA 852 (CR2)• NWA 2086 (CV3)• NWA 800 (R4)• NWA 1929 (Howardite)• NWA 3140 (Ureilite)• Canyon Diablo (iron)• Nantan (Iron)• Sikhote-Alin (Iron)
NWA stands for North West Africa
• Acapulcoites• Angrites• Ataxites• Aubrites• Brachinites• CB• CH• CI• CI• CK• CM• CO• CR• CV• Diogenites
• EH• EL • Eucrites• H• Hexahedrites • Howardites• L• LL• Lodranites• Mesosiderites• Octahedrites• Pallasites• R• Ureilites• Winonaites
Basic types
• Stony – primarily silicates (but can have some FeNi)
• Stony-Iron – ~50-50 mixture of silicates and FeNi• Stony-Iron – ~50-50 mixture of silicates and FeNi• Iron –almost all FeNi
(Silicates are minerals containing Silicon, and usually Oxygen.)
Basic types
primarily silicates (but can have some
50 mixture of silicates and FeNi50 mixture of silicates and FeNi
(Silicates are minerals containing Silicon, and
Types of Stony Meteorites
• Chondrites – Heated but have not melted– Tend to contain chondrules– Aggregates of high- and low– Aggregates of high- and low
• Achondrites – Heating to the point of melting– Tend to differentiate
• Where material segregates due to density
Types of Stony Meteorites
Heated but have not meltedTend to contain chondrules
and low-temperature componentsand low-temperature components
Heating to the point of melting
Where material segregates due to density
• Chondritic body
• Differentiated body
Ordinary Chondrites
• Most common type of meteorite to fall to Earth• Ordinary Chondrites – primarily olivine, pyroxene,
and metal– H – high-iron – 34% of falls– L – low-iron – 38% of falls– LL – very low-iron – 8% of falls
Ordinary Chondrites
Most common type of meteorite to fall to Earthprimarily olivine, pyroxene,
34% of falls38% of falls
8% of falls
Ordinary Chondrites
• H chondrites– ~30% olivine, ~30% pyroxene, ~20% FeNi– Fa17-Fa20 Fs15-Fs
• L chondrites • L chondrites – ~40% olivine, ~30% pyroxene, ~10% FeNi– Fa23-Fa26 Fs19-Fs
• LL chondrites– ~50% olivine, ~25% pyroxene, ~5% FeNi– Fa27-Fa31 Fs22-Fs
Ordinary Chondrites
~30% olivine, ~30% pyroxene, ~20% FeNiFs17
~40% olivine, ~30% pyroxene, ~10% FeNiFs21
~50% olivine, ~25% pyroxene, ~5% FeNiFs25
Within each ordinary chondrite group
• Type 3 are the most primitive (least heated)• Type 4 has been heated to higher temperatures• Type 5 heated to higher temperatures than type 4• Type 5 heated to higher temperatures than type 4• Type 6 heated to higher temperatures than type 5• Pictures
Within each ordinary chondrite group
Type 3 are the most primitive (least heated)Type 4 has been heated to higher temperaturesType 5 heated to higher temperatures than type 4Type 5 heated to higher temperatures than type 4Type 6 heated to higher temperatures than type 5
Carbonaceous Chondrites
• Meteorites that contains high levels of water and organic compounds
• Water is in hydrated silicates• Water is in hydrated silicates• Have not undergone significant heating (>200
since they formed
Carbonaceous Chondrites
Meteorites that contains high levels of water and
Water is in hydrated silicatesWater is in hydrated silicatesHave not undergone significant heating (>200°C)
Carbonaceous Chondrites• CI1 I is for Ivuna• CM2 M is for Mighei• CR2 R is for Renazzo• CH2 H is for High• CB3 B is for Bencubbin• CO3 O is for Ornans• CV3 V is for Vigarano• CK3 K is for Karoonda
– Could be CK4 or CK5
Carbonaceous ChondritesI is for IvunaM is for MigheiR is for RenazzoH is for High-MetalB is for BencubbinO is for OrnansV is for VigaranoK is for Karoonda
Alteration Sequence
• 3 is most primitive• 2 has been aqueously altered• 1 has been aqueously altered more than 2• 1 has been aqueously altered more than 2
Alteration Sequence
2 has been aqueously altered1 has been aqueously altered more than 21 has been aqueously altered more than 2
CI1 chondrite
• Ivuna – up to 20 wt.% water
CI1 chondrite
up to 20 wt.% water
CI chondrites haveelemental compositionssimilar to the Sun
CI chondrites haveelemental compositionssimilar to the Sun
CM2 chondrite
• Murchison
CM2 chondrite
CV3 chondrite
• Allende • Fell February 8, 1969 • Over 2,000 kilograms of material • Over 2,000 kilograms of material
was recovered
CV3 chondrite
Over 2,000 kilograms of material Over 2,000 kilograms of material
CV3 chondrite
• Contain chondrules• And Calcium Aluminum Inclusions (CAIs)
– They consist of high-temperature minerals, including – They consist of high-temperature minerals, including silicates and oxides containing calcium, aluminum, and titanium.
– Some CAIs were dated at 4.57 billion years, making them the oldest known objects in the solar system
CV3 chondrite
And Calcium Aluminum Inclusions (CAIs)temperature minerals, including temperature minerals, including
silicates and oxides containing calcium, aluminum,
Some CAIs were dated at 4.57 billion years, making them the oldest known objects in the solar system
Difference
• Chondrules are round and composed mostly of silicate minerals like olivine and pyroxene
• CAIs are predominantly white to light gray in • CAIs are predominantly white to light gray in color and irregularly shaped and rich in refractory minerals like melilite and spinel
• Melilite - (Ca,Na)2(Al,Mg)(Si,Al)• Spinel - MgAl2O4
Difference
Chondrules are round and composed mostly of silicate minerals like olivine and pyroxeneCAIs are predominantly white to light gray in CAIs are predominantly white to light gray in color and irregularly shaped and rich in refractory minerals like melilite and spinel
(Al,Mg)(Si,Al)2O7
Other types of chondrites
• Enstatite Chondrites (EH and EL) enstatite (Magnesium silicate)
• R chondrites –primarily olivine, no FeNi• R chondrites –primarily olivine, no FeNi
Other types of chondrites
Enstatite Chondrites (EH and EL) – primarilyenstatite (Magnesium silicate)
primarily olivine, no FeNiprimarily olivine, no FeNi
tiny crystalline grains found in the fine
meteorites, and are assumed to be older than the solar system.
tiny crystalline grains found in the fine-grained matrix of primitive
meteorites, and are assumed to be older than the solar system.
Achondrites
• Stony meteorites that were heated to the point of melting– HEDs – basaltic crust (lava flows)– Eucrites - pigeonite and plagioclase– Howardites - mixtures of eucrite and diogenite
material– Diogenites - orthopyroxene
• HEDs are thought to be fragments of asteroid 4 Vesta
Achondrites
Stony meteorites that were heated to the point of
basaltic crust (lava flows)pigeonite and plagioclase
mixtures of eucrite and diogenite
orthopyroxeneHEDs are thought to be fragments of asteroid 4
Differentiation
• Meteorites from the same parent body can have a very different composition if they are from a parent body that has differentiated
• Basaltic crust• Olivine Mantle• FeNi core
Differentiation
Meteorites from the same parent body can have a very different composition if they are from a parent body that has differentiated
Eucrites
• Basalts• Contain pigeonite and
plagioclase
Eucrites
Diogenites
• mainly magnesium-rich orthopyroxene
• Minor plagioclase• Sometimes olivine
Diogenites
Howardites
• Mixture of eucritic and diogenitic material
Howardites
Aubrites
• Enstatite-rich achondrite
Aubrites
Angrites
– contain predominately anorthite, Alhedenbergite, and Ca-rich olivine
Angrites
contain predominately anorthite, Al-Ti diopside-rich olivine
Irons• FeNi• Some show the growth of two FeNi minerals with
different crystal structures• Widmanstätten pattern – shows when etched with
weak acidweak acid• Kamacite – light – Ni-poor • Taenite – dark – Ni-rich• Most thought to be cores of
differentiated bodies
Irons
Some show the growth of two FeNi minerals with
shows when etched with
Most thought to be cores of
Widmanstätten pattern
• Widmanstätten patternsinterleaving kamacite and taenite bands (or ribbons) called lamellae. ribbons) called lamellae.
Widmanstätten pattern
Widmanstätten patterns are composed of interleaving kamacite and taenite bands (or
. .
• Kamacite - metallic iron with up to 7.5% nickel• Taenite - iron with 20-65% nickel
metallic iron with up to 7.5% nickel65% nickel
Irons
• Ataxite – made almost entirely of taenite (more than 16% Ni)
• Octahedrite – composed of both taenite and • Octahedrite – composed of both taenite and kamacite (6-16% Ni)
• Hexahedrite - composed almost entirely of kamacite (less than 6% Ni)
Irons
made almost entirely of taenite (more
composed of both taenite and composed of both taenite and
composed almost entirely of kamacite (less than 6% Ni)
Ataxite
• Made almost entirely of taenite
Ataxite
Octahedrite
• Have Widmanstätten pattern
• Plessite are the spaces between larger kamacite between larger kamacite and taenite plates are often filled by a fine-grained mixture of kamacite and taenite
Octahedrite
Hexahedrite
• Often have fine parallel line called Neumann lines
• Shock-induced, structural deformation of the deformation of the kamacite
Hexahedrite
Stony-
• Pallasites• Mesosiderites
-Irons
Pallasite
• Olivine and FeNi
Pallasite
Mesosiderite
• Mixture of silicates and metallic iron
• Silicate material is similar to that found in HEDsto that found in HEDs
Mesosiderite
Primitive Achondrites
• Experienced a limited amount of melting so they have bulk compositions and mineralogies similar to chondritic meteoritesto chondritic meteorites– Acapulcoites – olivine, pyroxene, FeNi– Lodranites – olivine, pyroxene, FeNi– Winonaites - olivine, pyroxene, FeNi
Primitive Achondrites
Experienced a limited amount of melting so they have bulk compositions and mineralogies similar
olivine, pyroxene, FeNiolivine, pyroxene, FeNiolivine, pyroxene, FeNi
How old is the solar system?How old is the solar system?
How old is the solar system?
• ~4.6 billion years• All meteorites tend to have these ages• Except:• Except:
How old is the solar system?
All meteorites tend to have these ages
How old is the solar system?
• ~4.6 billion years• All meteorites tend to have these ages• Except:• Except:
– Martian meteorites– Lunar meteorites
How old is the solar system?
All meteorites tend to have these ages
Ages
• Ages
Ages
How do you determine this age?How do you determine this age?
Dating a planetary surface
• Radioactive Dating – Need sample• Crater counting – Need image of surface
Dating a planetary surface
Need sampleNeed image of surface
Radioactivity
• The spontaneous emission of radiation (light and/or particles) from the nucleus of an atom
Radioactivity
The spontaneous emission of radiation (light and/or particles) from the nucleus of an atom
Radioactivity
http://wps.prenhall.com/wps/media/tmp/labeling/2130796_dyn.jpg
Radioactivity
http://wps.prenhall.com/wps/media/tmp/labeling/2130796_dyn.jpg
Half-
• The time required for half of a given sample of a radioactive isotope (parentdaughter isotope. daughter isotope.
-Life
The time required for half of a given sample of a parent) to decay to its
Radioactive Dating• You are dating when a rock crystallized
http://faculty.weber.edu/bdattilo/images/tim_rock.gif
Radioactive DatingYou are dating when a rock crystallized
http://faculty.weber.edu/bdattilo/images/tim_rock.gif
Radioactive Datingn = no(1/2)(t/half-life)
no = original amountn = amount left after decay
Also can write the formula asn = noe-λt
λ is the decay constantdecay constant is the fraction of a number of atoms of a
radioactive nuclide that disintegrates in a unit of timeHalf life = (ln 2)/λ = 0.693/λ
Radioactive Dating
decay constant is the fraction of a number of atoms of a radioactive nuclide that disintegrates in a unit of time
• where e = 2.718 281 828 459 045 …
• Limit (1 + 1/n)n = e• Limit (1 + 1/n)n = en→∞
• For example if you have n = 1,000• The limit would be 2.716924
2.718 281 828 459 045 …
For example if you have n = 1,000The limit would be 2.716924
Exponential decay is where the rate of decayis directly proportional to the amount present
http://www.gpc.edu/~pgore/myart/radgraph.gif
Exponential decay is where the rate of decayis directly proportional to the amount present.
http://www.gpc.edu/~pgore/myart/radgraph.gif
• x = by
• y = logb(x)
• For example,• 100 = 102
• 2 = log10(100)
• 0.01 = 10-2
• -2 = log10(0.01)
• 2 = e0.693
• 0.693 = lne2
Remember
• Number of original atoms (parent atoms)• = number of daughter atoms today + number of
parent atoms todayparent atoms today
Remember
Number of original atoms (parent atoms)= number of daughter atoms today + number of
http://academic.brooklyn.cuny.edu/geology/leveson/core/topics/time/graphics/radio1.gifhttp://academic.brooklyn.cuny.edu/geology/leveson/core/topics/time/graphics/radio1.gif
What are the assumptions to get an age?What are the assumptions to get an age?
What are the assumptions?
• No loss of parent atoms– Loss will increase the apparent age of the sample.
• No loss of daughter atoms– Loss will decrease the apparent age of the sample. – Loss will decrease the apparent age of the sample.
• No addition of daughter atoms or if daughter atoms was present when the sample formed– If there was, the age of the sample will be inflated
• These can possibly be all corrected for
What are the assumptions?
Loss will increase the apparent age of the sample.
No loss of daughter atomsLoss will decrease the apparent age of the sample. Loss will decrease the apparent age of the sample.
No addition of daughter atoms or if daughter atoms was present when the sample formed
If there was, the age of the sample will be inflated
These can possibly be all corrected for
Basic Formula
• Number of daughter atoms formed = number of parent atoms consumed
• If there were daughter atoms originally there• If there were daughter atoms originally there• D – Do = no - n• Remember: n = noe-λt so n• D- Do = n eλt – n• D = Do + n (eλt – 1)
Basic Formula
Number of daughter atoms formed = number of
If there were daughter atoms originally thereIf there were daughter atoms originally there
so no = n eλt
Commonly Used Long-Lived Isotopes in Geochronology
RadioactiveParent (P)
RadiogenicDaughter
(D)
StableReference
(S)
40K 40Ar 36Ar
87Rb 87Sr 86Sr
147Sm 143Nd 144Nd147Sm 143Nd 144Nd
232Th 208Pb 204Pb
235U 207Pb 204Pb
238U 206Pb 204Pb
StableReference
(S)
Half-life, t½
(109 y)
Decay constant, l
(y-1)
1.25 0.58x10-10
48.8 1.42x10-11
144Nd 106 6.54x10-12144Nd 106 6.54x10-12
14.01 4.95x10-11
0.704 9.85x10-10
4.468 1.55x10-10
How do you determine isotopic values?How do you determine isotopic values?
How do you determine isotopic values?
• Mass Spectrometer
How do you determine isotopic values?
It is easier
• To determine ratios of isotopic values than actual abundances
It is easier
To determine ratios of isotopic values than actual
Example
• 87Rb → 87Sr + electron + antineutrino + energy• Half-life is 48.8 billion years• 87Sr = 87Srinitial + 87Rb (eλt –
• Divide by stable isotope
• 87Sr = 87Srinitial + 87Rb (eλt –86Sr 86Sr 86Sr
Example
Sr + electron + antineutrino + energylife is 48.8 billion years
– 1)
– 1)
Example
• Formula for line• 87Sr = 87Srinitial + (eλt – 1) 87
86Sr 86Sr 8686Sr 86Sr 86
y = b + m x
Example
87Rb86Sr86Sr
http://www.asa3.org/aSA/resources/wiens2002_images/wiensFig4.gifhttp://www.asa3.org/aSA/resources/wiens2002_images/wiensFig4.gif
= (eλt – 1)
Carbon
• 99% of the carbon is Carbon• 1% is Carbon-13• 0.0000000001% is Carbon• 0.0000000001% is Carbon• The half-life of carbon-14 is 5730• It decays into nitrogen-14 through beta
(electron and an anti-neutrino are emitted).
Carbon-14
99% of the carbon is Carbon-12
0.0000000001% is Carbon-140.0000000001% is Carbon-1414 is 5730±40 years. 14 through beta-decay
neutrino are emitted).
• Due to Carbon-14’s short halfobjects up to 60,000 years old
14’s short half-life, can only date objects up to 60,000 years old
• Plants take up atmospheric carbon through photosynthesis
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/cardat.html
Plants take up atmospheric carbon through
astr.gsu.edu/hbase/nuclear/cardat.html
• When something dies, it stops being equilibrium with the atmosphere
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/cardat.html
When something dies, it stops being equilibrium
astr.gsu.edu/hbase/nuclear/cardat.html
Why is Carbon-14 still present if it has such a short half
14 still present if it has such a short half-life?
Why is Carbon-14 still present if it has such a short half
• Cosmic rays impact Nitrogen
• Cosmic rays are energetic particles (90% are protons) • Cosmic rays are energetic particles (90% are protons) originating from space. From the Sun (solar cosmic rays) or outside the solar system (galactic cosmic rays)
• n + 14N → 14C + p
14 still present if it has such a short half-life?
Cosmic rays impact Nitrogen-14 and create Carbon-14
Cosmic rays are energetic particles (90% are protons) Cosmic rays are energetic particles (90% are protons) originating from space. From the Sun (solar cosmic rays) or outside the solar system (galactic cosmic rays)
• http://en.wikipedia.org/wiki/Image:Radiocarbon_bomb_spike.svghttp://en.wikipedia.org/wiki/Image:Radiocarbon_
What heats the asteroids?What heats the asteroids?
Radioactive Heating
• Generally thought to be due to • 26Al → 26Mg + electron + energy• Half-life of only 700,000 years• Releases lots of energy• If 0.005% of all the aluminum in a chondrite was
26Al, (most is aluminum-radioactive), it would release enough energy to melt asteroids a few kilometers across and larger
Radioactive Heating
Generally thought to be due to 26AlMg + electron + energy
life of only 700,000 years
If 0.005% of all the aluminum in a chondrite was -27, which is not
radioactive), it would release enough energy to melt asteroids a few kilometers across and larger
Types of Planetary Missions
• Fly By• Orbiter• Lander• Lander
– Atmospheric Probe– Rover– Manned
• Sample Return
Types of Planetary Missions
Mercury/Venus
• Mercury is the closest planet to the Sun• Venus is next closest
Mercury/Venus
Mercury is the closest planet to the Sun
Mercury
• orbit: 0.38 AU from Sun• diameter: 4,880 km (38.3% of Earth)• mass: 3.30 x 1023 kg (5.5% of Earth)• mass: 3.30 x 10 kg (5.5% of Earth)• temperature:
90 K (minimum) 440 K (average)700 K (maximum)
• Satellites: Zero
Mercury
orbit: 0.38 AU from Sundiameter: 4,880 km (38.3% of Earth)
kg (5.5% of Earth)kg (5.5% of Earth)
Difficult to study Mercury
• Because of Mercury's proximity to the Sun– makes reaching it with spacecraft technically
challengingchallenging– Earth-based observations difficult.
Difficult to study Mercury
Because of Mercury's proximity to the Sunmakes reaching it with spacecraft technically
based observations difficult.
Mercury
• Videos• http://www.gecdsb.on.ca/d&g/astro/html/Mercury
.html.html
Mercury
http://www.gecdsb.on.ca/d&g/astro/html/Mercury
Mariner 10
• The first spacecraft to approach Mercury was NASA's Mariner 10 (1974
Mariner 10
The first spacecraft to approach Mercury was NASA's Mariner 10 (1974-1975).
Caloris BasinCaloris Basin
Caloris Basin(Some of the hill are 1,800 meters tall)
Caloris Basin(Some of the hill are 1,800 meters tall)
Messenger dataMariner 10 data
Caloris Basin• A basin was defined by Hartmann and Kuiper (1962) as a
"large circular depression with distinctive concentric rings and radial lineaments."
• Others consider any crater larger than 200 kilometers a basin. basin.
• The Caloris basin is 1,550 kilometers in diameter, and was probably caused by a projectile larger than 100 kilometers in size.
• The impact produced concentric mountain rings three kilometers high and sent ejecta 600 to 800 kilometers across the planet.
Caloris BasinA basin was defined by Hartmann and Kuiper (1962) as a "large circular depression with distinctive concentric rings and radial lineaments." Others consider any crater larger than 200 kilometers a
The Caloris basin is 1,550 kilometers in diameter, and was probably caused by a projectile larger than 100
The impact produced concentric mountain rings three kilometers high and sent ejecta 600 to 800 kilometers
MoonMoon
Weird TerrainThe weird terrain is almost opposite Caloris Basin. It consists of hills, ridges and grooves that cut across craters. The weird terrain my have been formed by shock waves that raced through the center of the planet and outward early in of the planet and outward early in Mercury's history.
Weird Terrain
ridges and grooves that cut across craters. The weird terrain my have been formed by shock waves that raced through the center
Mercury has high density
• Its density is 5.44 g/cm3
Earth's 5.52g/cm3 density. • In an uncompressed state, Mercury's density is 5.5 • In an uncompressed state, Mercury's density is 5.5
g/cm3 where Earth's is only 4.0 g/cm
Mercury has high density
which is comparable to density.
In an uncompressed state, Mercury's density is 5.5 In an uncompressed state, Mercury's density is 5.5 g/cm3 where Earth's is only 4.0 g/cm3.
http://www.psrd.hawaii.edu/WebImg/MercuryCore.gifhttp://www.psrd.hawaii.edu/WebImg/MercuryCore.gif
Magnetic Field
• Despite its small size and slow 59rotation, Mercury has a significant, and apparently global, magnetic field. apparently global, magnetic field.
• It is about 1.1% as strong as the Earth’s.• Particularly strong tidal effects caused by the
planet's high orbital eccentricity would serve to keep the core in the liquid state so it could have a dynamo
Magnetic Field
Despite its small size and slow 59-day-long rotation, Mercury has a significant, and apparently global, magnetic field. apparently global, magnetic field. It is about 1.1% as strong as the Earth’s.Particularly strong tidal effects caused by the planet's high orbital eccentricity would serve to keep the core in the liquid state so it could have a
Messenger
• Mission to Mercury• Launched August 3, 2004• Flew by Mercury in 2008 • Flew by Mercury in 2008
and 2009• Will orbit Mercury in
2011
Messenger
Messenger video• A set of five 11-band images was captured by MESSENGER
just after the spacecraft crossed the night/day line (the “terminator”), which are the highestever obtained of Mercury’s surface.
• At the beginning of this movie, it is dawn in that region of Mercury, and the Sun is just off the horizon. The long shadows that are cast by crater walls exaggerate the ruggedness of the terrain and highlight variations in ruggedness of the terrain and highlight variations in topography.
• Though Mercury’s true colors are subtle, the 11 color bands of MDIS were combined in a statistical method used to highlight differences in color units. Older, lowand relatively blue material is encroached by younger, relatively red smooth plains. Several lobate scarps or cliffs are observed, which are places where compressional stresses caused Mercury’s crust to fracture and shorten.
http://messenger.jhuapl.edu/news_room/presscon5_images/Robinson%20Image%205.7.mov
Messenger videoband images was captured by MESSENGER
just after the spacecraft crossed the night/day line (the “terminator”), which are the highest-resolution color images ever obtained of Mercury’s surface. At the beginning of this movie, it is dawn in that region of Mercury, and the Sun is just off the horizon. The long shadows that are cast by crater walls exaggerate the ruggedness of the terrain and highlight variations in ruggedness of the terrain and highlight variations in
Though Mercury’s true colors are subtle, the 11 color bands of MDIS were combined in a statistical method used to highlight differences in color units. Older, low-reflectance, and relatively blue material is encroached by younger, relatively red smooth plains. Several lobate scarps or cliffs are observed, which are places where compressional stresses caused Mercury’s crust to fracture and shorten.
http://messenger.jhuapl.edu/news_room/presscon5_images/Robinson%20Image%205.7.mov
Mercury
http://space.newscientist.com/data/images/ns/cms/dn14893/dn14893
Much of the image to the right of the Kuiper crater (in the centre here) had never been imaged by a spacecraft before. Researchers were surprised to see long crater rays that extend thousands of kilometers from a crater at the planet's north pole
Mercury
http://space.newscientist.com/data/images/ns/cms/dn14893/dn14893-1_450.jpg
Much of the image to the right of the Kuiper crater (in the centre here) had never been imaged by a spacecraft before. Researchers were surprised to see long crater rays that extend thousands of kilometers from
Mercury
Dark material, shown in deep blue in the enhanced colour image at right (a composite of visible and nearby impacts. The material seems to be widespread but patchy, suggesting the planet's interior is not homogenous.
http://space.newscientist.com/data/images/ns/cms/dn15077/dn15077
Mercury
Dark material, shown in deep blue in the enhanced colour image at right (a composite of visible and near-infrared images), was kicked up by impacts. The material seems to be widespread but patchy, suggesting the planet's interior is not homogenous.
http://space.newscientist.com/data/images/ns/cms/dn15077/dn15077-1_600.jpg
Mercury• Double ringed basin• 290 km in diameter• Appears young (few
craters on it)craters on it)• ~ 1 billion years old• Lava may have
covered up the central part of the basin
htt
Mercury
http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/presscon6_img4_5_lg.jpg
• 160 km in diameter
http://en.wikipedia.org/wiki/File:Mercury_Doublehttp://en.wikipedia.org/wiki/File:Mercury_Double-Ring_Impact_Basin.png
Spectra of Mercury
Weak to absent absorption features
Spectra of Mercury
Weak to absent absorption features – no iron in the silicates
Mercury’s Surface
• Possibly made of Enstatite (MgSiOpyroxene
• Possibly made of material like the Lunar • Possibly made of material like the Lunar Highlands– Plagioclase feldspar - CaAl
Mercury’s Surface
Possibly made of Enstatite (MgSiO3) – Mg-rich
Possibly made of material like the Lunar Possibly made of material like the Lunar
CaAl2Si2O8
Questions:
• Why does Mercury have such a large iron core?
Questions:
Why does Mercury have such a large iron core?
One possibility
• Mercury may have been struck by a planetesimal of approximately 1/6 its mass and several hundred kilometers across.kilometers across.
• The impact would have stripped away much of the original crust and mantle, leaving the core behind as a relatively major component.
One possibility
Mercury may have been struck by a planetesimal of approximately 1/6 its mass and several hundred
The impact would have stripped away much of the original crust and mantle, leaving the core behind as a relatively major component.
Venus• orbit: 0.72 AU from Sun• diameter: 12,103.6 km (94.9% of Earth)
(called Earth‘s twin)• mass: 4.869 x 1024 kg (81.5% of Earth)• mass: 4.869 x 1024 kg (81.5% of Earth)• Temperature on surface:
726 K(average)• Satellites: Zero
Venusorbit: 0.72 AU from Sundiameter: 12,103.6 km (94.9% of Earth)
kg (81.5% of Earth)kg (81.5% of Earth)Temperature on surface:
Venus’ atmosphere• Atmospheric pressure at surface is 92 times the
pressure on the Earth’s surface
• Atmospheric content:• Carbon dioxide 96.5 %• Nitrogen 3.5 %• Nitrogen 3.5 %• Sulfur dioxide 150 ppm• Argon 70 ppm• Water vapor 20 ppm
Venus’ atmosphereAtmospheric pressure at surface is 92 times the pressure on the Earth’s surface
Venus’ clouds
• Venusian clouds are thick and are composed of sulfur dioxide and droplets of sulfuric acid.
• These clouds reflect about 75%• These clouds reflect about 75%that falls on them,
Venus’ clouds
Venusian clouds are thick and are composed of sulfur dioxide and droplets of sulfuric acid.These clouds reflect about 75% of the sunlight These clouds reflect about 75% of the sunlight
Greenhouse Effect• The greenhouse effect is the rise in temperature
that a planet experiences because certain gases in the atmosphere (H2O, COemitted from the surface.
• Visble light hits the surface• Surface warms and emits infrared radiation• Atmospheric gases absorb some of the infrared
light• Surface and Atmosphere heat up
Greenhouse EffectThe greenhouse effect is the rise in temperature that a planet experiences because certain gases in
O, CO2, CH4) trap energy emitted from the surface. Visble light hits the surfaceSurface warms and emits infrared radiationAtmospheric gases absorb some of the infrared
Surface and Atmosphere heat up
Runaway Greenhouse Effect
• Runaway greenhouse effect to describe the effect as it occurs on Venus
• Venus is sufficiently strongly heated by the Sun • Venus is sufficiently strongly heated by the Sun that water is vaporized and so carbon dioxide is not reabsorbed by the planetary crust
Runaway Greenhouse Effect
Runaway greenhouse effect to describe the effect
Venus is sufficiently strongly heated by the Sun Venus is sufficiently strongly heated by the Sun that water is vaporized and so carbon dioxide is not reabsorbed by the planetary crust
Why does Venus has such a thick atmosphere?
• The luminosity of the Sun has increased by 25% from 3.8 billion years ago
• The atmosphere of Venus up to around 4 billion years ago maybe was more like that of Earth with years ago maybe was more like that of Earth with liquid water on the surface.
• The runaway greenhouse effect may have been caused by the evaporation of the surface water and the rise of the levels of greenhouse gases that followed.
Why does Venus has such a thick atmosphere?
The luminosity of the Sun has increased by 25% from 3.8 billion years agoThe atmosphere of Venus up to around 4 billion years ago maybe was more like that of Earth with years ago maybe was more like that of Earth with liquid water on the surface. The runaway greenhouse effect may have been caused by the evaporation of the surface water and the rise of the levels of greenhouse gases that
Surface
• Mapped by Magellan spacecraft (1990-1994)
• How was it mapped if it has a dense atmosphere?has a dense atmosphere?
Surface
How did it do it?
• Used Radar (radio waves)
How did it do it?
Used Radar (radio waves)
• Most of Venus' surface consists of gently rolling plains with little relief.
• Data from Magellan's imaging radar shows that • Data from Magellan's imaging radar shows that much of the surface of Venus is covered by lava flows.
• Lava flows stopped ~300• Very few craters
Most of Venus' surface consists of gently rolling
Data from Magellan's imaging radar shows that Data from Magellan's imaging radar shows that much of the surface of Venus is covered by lava
Lava flows stopped ~300-500 million years ago
• Most volcanoes on Venus are shield volcanoes• Low viscosity lava
Most volcanoes on Venus are shield volcanoes
Maat Mons
• Highest volcano on Venus• 8 km high• Shield Volcano• Shield Volcano• Could be active
Maat Mons
Volcanoes
• ~170 giant volcanoes over 100 km across• On Earth, only the Big Island of Hawaii is this
largelarge• This is due to Venus’ crust being older• Earth’s crust is continually being recycled by
subduction
Volcanoes
~170 giant volcanoes over 100 km acrossOn Earth, only the Big Island of Hawaii is this
This is due to Venus’ crust being olderEarth’s crust is continually being recycled by
Craters
• Venusian craters range from 3diameter.
• There are no craters smaller than 3• There are no craters smaller than 3the dense atmosphere stops small incoming objects.
Craters
Venusian craters range from 3 km to 280 km in
There are no craters smaller than 3 km because There are no craters smaller than 3 km because the dense atmosphere stops small incoming
• 200 km long channel• 2 km wide
http://hyperphysics.phy-astr.gsu.edu/hbase/Solar/venusurf.html
Pancakes Domes
• Flattened lava domes are attributed to upwellings of molten rock which then subsided.
• The solid crust left behind • The solid crust left behind then flattened and cracked.
Pancakes Domes
Flattened lava domes are attributed to upwellings of molten rock which then subsided. The solid crust left behind The solid crust left behind
Coronae• Corona is an oval-shaped feature. • hot rising bodies of magma reach the crust and
cause it to partially melt and collapse• Generates volcanic flows and fault
patterns that radiate from the patterns that radiate from the central structure.
http://pds.jpl.nasa.gov/planets/captions/venus/vencor.htm
100 km in diameter
Coronaeshaped feature.
hot rising bodies of magma reach the crust and cause it to partially melt and collapseGenerates volcanic flows and fault patterns that radiate from the patterns that radiate from the
100 km in diameter
Arachnoids
• concentric ovals surrounded by a complex network of fractures, and can span 200 kilometers
Arachnoids
concentric ovals surrounded by a complex network of fractures, and can span 200 kilometers
• Almost all Venusian surface features are named after historical and mythological women.
• The only exceptions are Maxwell Montes, named • The only exceptions are Maxwell Montes, named after James Clerk Maxwell, and two highland regions, Alpha Regio and Beta Regio
Almost all Venusian surface features are named after historical and mythological women.The only exceptions are Maxwell Montes, named The only exceptions are Maxwell Montes, named after James Clerk Maxwell, and two highland regions, Alpha Regio and Beta Regio
Venera
• Venera probes were launched by the Soviet Union and enter Venus’ atmosphere
• 1961-1984• 1961-1984• Venera 3-16• 10 probes landed on surface
Venera
Venera probes were launched by the Soviet Union and enter Venus’ atmosphere
10 probes landed on surface
Venera 9Venera 9
Venera 9 and 10 picturesVenera 9 and 10 pictures
Venera 13Venera 13
Venera 13Venera 13
Venera 13Venera 13
Pioneer
• Pioneer Venus 1 or Pioneer Venus Orbiterlaunched in 1978 and studied the planet for more than a decade after orbital insertion in 1978.than a decade after orbital insertion in 1978.
• Pioneer Venus 2 or Pioneer Venus Multiprobesent four small probes into the Venusian atmosphere.
Pioneer
Pioneer Venus Orbiter was launched in 1978 and studied the planet for more than a decade after orbital insertion in 1978.than a decade after orbital insertion in 1978.
Pioneer Venus Multiprobesent four small probes into the Venusian
Pioneer 2Pioneer 2
Pioneer 2 bus• The Pioneer Venus bus portion of the spacecraft was targeted
to enter the Venusian atmosphere at a shallow entry angle and transmit data until destruction by the heat of atmospheric friction.
• The objective was to study the structure and composition of the atmosphere down to the surface, the nature and composition of atmosphere down to the surface, the nature and composition of the clouds, etc.
• With no heat shield or parachute, the bus made upper atmospheric measurements down to an altitude of about 165before disintegrating on December 9, 1978.
Pioneer 2 busportion of the spacecraft was targeted
to enter the Venusian atmosphere at a shallow entry angle and transmit data until destruction by the heat of atmospheric
The objective was to study the structure and composition of the atmosphere down to the surface, the nature and composition of atmosphere down to the surface, the nature and composition of
With no heat shield or parachute, the bus made upper atmospheric measurements down to an altitude of about 165 km before disintegrating on December 9, 1978.
Pioneer 2 Large Probe that entered the atmosphere
• Had parachute• a neutral mass spectrometer to measure the atmospheric
composition• a gas chromatograph to measure the atmospheric composition• a gas chromatograph to measure the atmospheric composition• a solar flux radiometer to measure solar flux penetration in the
atmosphere• an infrared radiometer to measure distribution of infrared radiation• a cloud particle size spectrometer t• a nephelometer to search for cloud particles• temperature, pressure, and acceleration sensors
Pioneer 2 Large Probe that entered the atmosphere
a neutral mass spectrometer to measure the atmospheric
a gas chromatograph to measure the atmospheric compositiona gas chromatograph to measure the atmospheric compositiona solar flux radiometer to measure solar flux penetration in the
an infrared radiometer to measure distribution of infrared radiationeter to measure particle size and shape
a nephelometer to search for cloud particlestemperature, pressure, and acceleration sensors
3 small probes
• No parachute
3 small probes
Venus Express
• Launched November 9, 2005 (SoyuzBaikonur, Kazakhstan)
• First global monitoring of composition of lower atmosphere in near-infrared transparency ‘windows’ atmosphere in near-infrared transparency ‘windows’
• First coherent study of atmospheric temperature and dynamics at different levels of atmosphere, from surface up to ~200 km
• First measurements from orbit of global surface temperature distribution
Venus Express
Launched November 9, 2005 (Soyuz-Fregat from
First global monitoring of composition of lower infrared transparency ‘windows’ infrared transparency ‘windows’
First coherent study of atmospheric temperature and dynamics at different levels of atmosphere, from surface
First measurements from orbit of global surface
Mostly spare parts from Mars Express or Rosetta
• ASPERA-4 - Neutral and ionised plasma analysis Express
• MAG - Magnetic field measurements • PFS - Atmospheric vertical sounding by infrared Fourier
spectroscopy - Mars Express • SPICAV - Atmospheric spectrometry by star or Sun • SPICAV - Atmospheric spectrometry by star or Sun
occultation - Mars Express • VeRa - Radio sounding of atmosphereFrance)VeRaRadio
sounding of atmosphere - Rosetta • VIRTIS - Spectrographic mapping of atmosphere and surface
- Rosetta • VMC - Ultraviolet and visible imaging Mars Express and
Rosetta
Mostly spare parts from Mars Express or Rosetta
Neutral and ionised plasma analysis - Mars
Magnetic field measurements - Rosetta Lander Atmospheric vertical sounding by infrared Fourier
Atmospheric spectrometry by star or Sun Atmospheric spectrometry by star or Sun
Radio sounding of atmosphereFrance)VeRaRadio Rosetta
Spectrographic mapping of atmosphere and surface
Ultraviolet and visible imaging Mars Express and
• http://www.hulu.com/watch/94012/themercury-and-venus---thehttp://www.hulu.com/watch/94012/the-universe-
the-inner-planets
Any Questions?Any Questions?Any Questions?Any Questions?