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Solar System: Planetary Science –Div. B
Help session: March 2nd, 2014Evolution of extraterrestrial ice and water in
the solar systemResources for test
“Two 8.5 x 11 inch two sided sheet”Test on March 15th, 2014
Test will include questions about a series of images projected onto the front of the room.
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Study points• Go to the web sites indicated on the rules sheet
and understand the mechanisms related to water that are responsible for observations made by scientists for objects in our solar system.
�Conceptual understanding is required, and some memorization.
�Terms to understand: Sublimation, evaporation, Melting, freezing, freezing point depression
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Mars North Polar CapSouth Polar CapEquatorial GlaciersPermafrost
Europa Thrace MaculaThera MaculaConamara ChaosRidges, Cycloids, Plains, Ocean
Enceladus Plumes, Jets, Tiger Stripes
Iapetus, Triton, Cere, Titan
Comets, The Kuiper Belt, The Oort Cloud
Mercury
Solar system objects known to have water
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Mars North Polar Cap from Mars surveyor
(http://www.msss.com/mars_images/moc/may_2000/n_pole/npole_50.jpg)
Extremely cold temperature,
The white stuff is frozen carbon dioxide not water but ….
Ice water is under this ����
Reflected Radar mapping of what is under the pole
Shallow Radar instrument on NASA's Mars Reconnaissance Orbiter for mapping underground ice-rich layers of the north polar layered terrain on Mars
The penetrating radar reveals icy layered deposits overlying a base rock.
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Ice layers
Base rock
Radar mapping of Mars North Polar cap
• Reflected radar map of frozen water just below the surface.
• From shallow radar instrument on the Mars Reconnaissance Orbiter
8http://www.nasa.gov/mission_pages/MRO/multimedia/mro20090922.html
• NASA's Mars Reconnaissance Orbiter, launched August 12, 2005, is on a search for evidence that water persisted on the surface of Mars for a long period of time. While other Mars missions have shown that water flowed across the surface in Mars' history, it remains a mystery whether water was ever around long enough to provide a habitat for life.
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• Photos from Mars Global Surveyor
• The bottom photo was taken during summer. This is essentially “permafrost” that is, it does not go away.
• CO2 frost grows much larger during winter.
• Picture taken by Mars Global Surveyor
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Mars South Polar cap
http://www.nasa.gov/centers/ames/multimedia/images/2005/marscap.html
• Mars Global Surveyor, launched in 1996, operated for about 9 years at Mars, longer at Mars than any other spacecraft in history, and for more than four times as long as the prime mission originally planned. The spacecraft returned detailed information that has overhauled understanding about Mars. Major findings include dramatic evidence that water still flows in short bursts down hillside gullies, and identification of deposits of water-related minerals leading to selection of a Mars rover landing site.
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Radar mapping of Mars South Polar cap• Reflected radar map of
frozen water just below the surface.
• The south polar region contains enough frozen water to cover the whole planet in a liquid layer approximately 11 meters (36 feet) deep.
• Covers an area bigger than texas.
12http://www.nasa.gov/mission_pages/mars/images/pia09224.html
Neutron emmission show hydrogen rich soils in Mars South Polar cap
• Soil enriched in hydrogen is indicated by the deep blue colors on the map
• From Mars Odyssey spacecraft
13http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA03487
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• Mars Odyssey Results• For the first time, the mission globally mapped the amount and
distribution of many chemical elements and minerals that make up the martian surface.
• Maps of hydrogen distribution led scientists to discover vast amounts of water ice in the polar regions buried just beneath the surface.
• Odyssey also recorded the radiation environment in low Mars orbit to determine the radiation-related risk to any future human explorers who may one day go to Mars.
15http://en.wikipedia.org/wiki/File:Wide_view_of_glacier_showing_image_field.JPG
Evidence for glaciers on Mars• Glaciers are largely restricted to
latitudes above 30° latitude. Based on models of the Martian atmosphere, ice should not be stable at the surface near the equator. Glaciers near the equator must be covered with a layer of rubble or dust preventing the sublimation of the ice into the atmosphere.
A terminal moraine is in the rectangle.
• http://en.wikipedia.org/wiki/File:ESP_028352_2245glacier.jpg
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More evidence for glaciers on Mars
Evidence that water still can flow on Mars
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• Phoenix Mars Lander's Surface Stereo Imager
• These images show sublimation of ice in the trench over the course of four days.
• In the lower left corner of the left image, a group of lumps is visible. In the right image, the lumps have disappeared, similar to the process of evaporation.
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Europa – a moon of Jupitor • Surface is composed of water ice• It is the “smoothest” object in the
solar system – no mountains• Surface is new – very few craters• Surface had cracks and streaks
– Thought to be cracks in ice.
• Smoothness and newness of the surface indicates liquid water – a subsurface ocean -- under the surface
• Water vapor has been detected• Photo taken by the Galileo probe
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• Galileo was a spacecraft which studied the planet Jupiter and its moons, as well as several other solar system bodies. Galileo arrived at Jupiter on December 7, 1995, and became the first spacecraft to orbit Jupiter. It launched the first probe into Jupiter, directly measuring its atmosphere.
• Jupiter's atmospheric composition and ammonia clouds were recorded, the clouds possibly created by outflows from the lower depths of the atmosphere. The data Galileo collected supported the theory of a liquid ocean under the icy surface of Europa, and there were indications of similar liquid-saltwater layers under the surfaces of Ganymede and Callisto
Europa
Europa surface close up• Conamara Chaos is a landscape produced by the disruption of the icy
crust of Europa. The region consists of rafts of ice that have moved around and rotated. Surrounding these plates is a lower matrix of jumbled ice blocks which may have been formed as water, slush, or warm ice rose up from below the surface. The region is cited as evidence for a subsurface ocean below Europa's icy surface.
Europa surface Thrace Macula
• Thrace Macula is the largest dark spot on Europa and has been recently modified and resurfaced. The nature of the dark material is uncertain but may have a higher concentration of salts or sulfates associated with the water ocean lying perhaps around as few as 6 miles (10 kilometers) beneath the surface. Some of this dark material appears to have ponded in low areas indicating that some liquid might be involved.
http://www.ciclops.org/view/4343/Thera_and_Thrace_Macula_on_Europa?js=1
• Thera Macula is the large dark spot next to Thrace Macula.
Europa surface Cycloids• Map of cycloid trace. Cycloids consist of curved segments and kinks
called cusps. Cycloid chains occur when multiple segments are linked by cusps and can be 100s to 1000s of km in length.
Cycloids grow as tensile fractures due
to tidal stresses.
Europa surface Ridges• features seen in this area is the double ridge cutt ing across the
picture from the lower left to the upper right. Thi s double ridge is about 2.6 km (1.6 miles) wide and stands some 300 m (330 yards) high. Small craters are most easily seen in the smo oth deposits along the south margin of the prominent double ridg e, and in the rugged ridged terrain farther south. The complexly ridged terrain seen here shows that parts of the icy crust of Euro pa have been modified by intense faulting and disruption, driven by energy from the planet's interior..
Enceladus: 6th largest moon of Saturn • Enceladus has liquid water under
its icy surface. Cryovolcanoes at the south pole shoot large jets of water vapor, other volatiles, and some solid particles (e.g. ice crystals, NaCl particles, etc.) into space, totaling approximately 200 kg per second. Some of this water falls back onto the moon as "snow", some of it adds to Saturn's rings, and some of it reaches Saturn. The whole of Saturn's E Ring is believed to have been made from these ice particles
• Photo from the
Cassini - Huygens spacecraft
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• Cassini–Huygens is an unmanned spacecraft sent to the planet Saturn. It is a flagship-class NASA-ESA-ASI robotic spacecraft sent to the Saturn system. It has studied the planet and its many natural satellites since arriving there in 2004, also observing Jupiter, the heliosphere, and testing the theory of relativity. Launched in 1997 after nearly two decades of development, it includes a Saturn orbiter and an atmospheric probe/lander for the moon Titan called Huygens, which entered and landed on Titan in 2005. Cassini is the fourth space probe to visit Saturn and the first to enter orbit, and its mission is ongoing as of 2014.
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Enceladus: Tiger stripes
• Near the south pole. The Tiger stripes mark the locations of the active jets of water ice and salt.
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Enceladus: Plumes / jets• Plumes results from heating of Enceladus' interior. That heating is thought to
be caused by squeezing and stretching of the moon as it goes along its path around Saturn. The squeezing and stretching happens because Enceladus' orbit is not perfectly circular. Enceladus should experience more tidal deformation (being squeezed into a shape of a football) when it's closer to Saturn, and that stress should be relaxed when it's farther from Saturn. That squeeze and release generates heat from friction, and it should also cause the fissures at its south pole to be pressed shut and crack open slightly,
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Iapetus: 3rd largest satellite of Saturn• Density indicates that it is mostly formed of ice. • Iapetus is locked in synchronous rotation about Saturn and that one side of
Iapetus is darker than the other, The dark material is a very thin layer, only a few tens of centimeters (approx. one foot) thick at least in some areas, according to Cassini radar imaging and the fact that very small meteor impacts have punched through to the ice underneath
• Dark area is warmer and ice sublimes. The bright areas are cooler and the ice condenses on it.
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Triton: Largest moon of Neptune• Triton is thought to have been captured from the Kuiper belt. Triton has a
surface of mostly frozen nitrogen, a mostly water ice crust, an icy mantle and a substantial core of rock and metal. The core makes up two-thirds of its total mass. Triton has a mean density of 2.061 grams per cubic centimetre (0.0745 lb/cu in) and is composed of approximately 15–35% water ice.
• Triton is one of the few moons in the Solar System known to be geologically active. As a consequence, its surface is relatively young, with a complex geological history revealed in intricate and mysterious cryovolcanic and tectonic terrains. Part of its crust is dotted with geysers thought to erupt nitrogen.
Photo from Voyager 2
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Voyager 2 is a space probe launched by NASA to study the outer Solar System and eventually interstellar space. It has been operating for 36 years, 5 months, and 8 days as of 28 January 2014; the spacecraft still receives and transmits data via the Deep Space Network
At a distance of 103.00 AU as of 28 January 2014 from Earth, it is one of the most distant human made objects Voyager 2 is in extended mission, tasked with locating and studying the boundaries of the Solar System, including the Kuiper belt, the heliosphere and interstellar space.
It encountered the Jovian system in 1979, Saturnian system in 1981, Uranian system in 1986, and the Neptunian system in 1989. It is still the only spacecraft to have visited the two outer giant planets Uranus and Neptune
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Ceres: • the largest asteroid and the only dwarf planet in the inner Solar System,
orbiting in the asteroid belt between the orbits of Mars and Jupiter. It is a rock–ice body 950 km (590 mi) in diameter and the smallest identified dwarf planet. It surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clay minerals. It appears to be differentiated into a rocky core and icy mantle, and may harbor an ocean of liquid water under its surface,
Hubble space telescope image
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Titan: The largest moon of Saturn • It is the only natural satellite known to have a dense atmosphere, and the
only object other than Earth for which clear evidence of stable bodies of surface liquid has been found. Titan is primarily composed of water ice and rocky material.
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Comets: • “Dirty snowballs”
• Comet Hartley 2 showing jetsphotographed by Deep Impact
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Deep Impact: • Deep Impact was a NASA space probe. It was designed to study the interior
composition of the comet 9P/Tempel, by releasing an impactor into the comet. The impactor successfully collided with the comet's nucleus. The impact excavated debris from the interior of the nucleus, allowing photographs of the impact crater. The photographs showed the comet to be more dusty and less icy than had been expected. The impact generated a large and bright dust cloud, which unexpectedly obscured the view of the impact crater.
Deep Impact continued to study extrasolar planets and comet Hartley 2.
solar system condensed out of intersteller gas and dust
• Gigantic gas and dust clouds (left over material spewed out by supernovae) condensed b by self gravity into globules.
• The globules spun up due to conservation of angular momentum. Became a spinning disk.
• The gas reached a critical density at the center and a star was formed.
• Can’t see the new star because it is “cloaked” in the gas and dust.
• Planets form as the surrounding material coalescences,
Early solar system evolution • Early in the sun’s life (as the planets were forming), the
sun had a very strong solar wind (from flares)– Charged particles streaming out of the suns atmosphere– This solar wind was produced as the nuclear reactions in the
core of the sun started.– The sun produces a weaker solar wind today that fluctuates with
the sunspot activity of the sun – more sunspots, more solar wind.• Solar wind “storms” cause the Northern Lights (auroras)
• This early strong solar wind “pushed” much of the material that had not been formed into planets out to the farther reaches of the solar system– This helped form the Oort Cloud (the source of long period
comets)
Kuiper Belt & Oort cloud• The Kuiper Belt is made up of
millions of icy and rocky objects that orbit our Sun beyond the orbits of Neptune and Pluto.
• These are planetesimals that did not combine to make planets.
• It is the source of short period comets
• Oort Cloud is spherical and is at the outer edge of our solar system
• It was pushed out there at the start of the solar system by strong solar winds and by the gravity of the large gas giant planets
• The Oort cloud acts as a reservoir for the long-period comets
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Phase diagram (next slide)
Liquid water always give off water vapor (gas)- The pressure of the water vapor depends on the temperature.- Water boils because the pressure of the water is the same
pressure as the air (1 atmosphere, 1 bar, 100 kPa)- BUT vapor will not be generated if the water is trapped (for
example, underground).
Frozen water (ice) always give off water vapor- The pressure of the water vapor depends on the temperature.- Ice does not boil- Even at the lowest temperatures, ice will have some water
vapor- Vapor will NOT be generated if the ice is trapped underground
Ammonia (NH3) or salt will lower the freezing point of the water. (2nd plot below). � Really cold objects can still have liquid water present.
41Ice always has vapor coming off of it
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-50 -25 0 25 50 75 100 125
T, C
0.1
100
0.01
10,000
100,000
0 C
100 C
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• Ammonia (NH3) is suspected as being present in a number of objects.
• This diagram shows that NH3 can drop the freezing point from 0C to -100 C at 32 wt% NH3!!!!
• So many very cold objects can still have liquid water as long as there is some ammonia present.
• The freezing point line divides the H2O(s) (ice) from the “liquid solution”
• Pure water is on the left line (0 wt% Ammonia). Water still freezes at 0C and boils at 100C.
• Add some NH3 and the freezing point drops in temperature.
