A1 09 Venus Mars Atmos

Venus’s AtmosphereLACC: §9.3, 9.5, 9.6

• Venus’s surface environment

• Venus’s atmospheric evolution = run-away greenhouse

• Venus’s cloud cover

An attempt to answer the “big questions”: what is out there? Are we alone?

1Thursday, March 11, 2010

Venus

http://www.astrosurf.com/nunes/explor/explor_m10.htm




Venus: Atmosphere

Composition

• CO2 96%

• N2 3.5%

• Ar 0.006%

• O2 0.003%

• Ne 0.001%

90 bars surface pressure

850°F average surface temperature (hotter than Mercury due to a 920°F greenhouse effect)

winds of a few mph


Venus: Greenhouse Effect

http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap09/FG09_19.jpg




Venus: Runaway Greenhouse Effect

Due to high temperatures, some (all?) of Venus’s H2O was in a gaseous state instead of a liquid state.

As an atmospheric gas, the sun’s uv light broke the H2O molecules apart--photodissociation.

The lighter H left the atmosphere--thermal escape; the heavier O is quite reactive and bonded with C (to make CO2), surface rocks (e.g. rust), or left the atmosphere via thermal escape.

Less water in general means less liquid water for the CO2 to dissolve in to, so atmospheric CO2 levels increase.

Higher atmospheric CO2 levels increase the surface temperature--greenhouse effect. Higher temperatures convert more liquid H2O into a gas. (Return to top and repeat.)


Venus: H2SO4 Clouds

http://lasp.colorado.edu/~bagenal/3720/CLASS16/16EVM-Dyn2.html




Venus: Atmosphere

Sulfuric acid, H2SO4, clouds!

Sulfur dioxide SO2 and H2O can combine to make H2SO4.

SO2 comes from volcanoes; but on Venus, SO2 becomes sulfuric acid clouds because there is no liquid water to dilute it.


Venus: Venera 13 & 14

http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-venus.html

Even though it’s covered by sulfuric acid clouds and has a surface air pressure of 90 bar, the Soviets managed several probe landings: Venera and Vega probes.




Venus’s AtmosphereLACC: §9.3, 9.5, 9.6

• Venus’s surface environment: 96% CO2, 90 bars, 850°F (planet-wide), slow rotation so less wind/erosion, constant cloud cover

• Venus’s atmospheric evolution = run-away greenhouse: high temperatures result in H2O gas which photodissociates, less liquid water so less CO2 dissolves out, high CO2 levels raise the temperature because of greenhouse effect...

• Venus’s cloud cover: sulfuric acid clouds



LACC HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe, 3rd ed.

• Ch. 9, pp. 219-220: 4.

Due at the beginning of the next class period.

Test covering chapters 6-9 next class period.

Be thinking about the Solar System Project.


Mars’s AtmosphereLACC: §9.3, 9.5, 9.6

• Mars’s surface environment

• Mars’s atmospheric evolution = run away refrigerator

• Mars’s clouds



Mars

http://rosetta.jpl.nasa.gov/dsp_images.cfm?buttonSel=gallery&buttonSelL2=images&category=mars




Mars: Atmosphere

Composition

• CO2 95.3%

• N2 2.7%

• Ar 1.6%

• O2 0.15%

• Ne 0.0003%

0.007 bar pressure

-67°F surface temperature

• 80°F hot day

• -200°F cold night

(11°F greenhouse)

winds of a few mph; massive dust storms


Mars’ Surface

Polar caps of H2O and CO2 ice.

Channels and gullies indicate liquid water flowed, but over 3 billion years ago.

Wind erosion occurs.


Mars: Runaway Refrigerator Effect

Mars’s lower surface gravity (0.38g) means it lost it’s atmospheric gases more readily--thermal escape.

As the planet’s atmosphere thinned, the greenhouse effect became less significant, so Mars grew colder.

Mars became so cold, even CO2 began to condense out of the atmosphere.

As CO2 condensed out of the atmosphere, the greenhouse effect became less significant so Mars grew even colder... i.e. a runaway refrigerator effect.

Eventually Mars became so cold and the air pressure too low for liquid H2O to exist on its surface.


Mars: Atmosphere

Occasionally, clouds of dust, H2O, and/or CO2 form.

The surface pressure is too low for liquid H2O, even when the temperature does get above freezing.

CO2 freezes at about -190°F. Much of Martian polar ice-caps are frozen CO2 (a.k.a. dry ice).


Mars: Dust Storms

http://abyss.uoregon.edu/~js/images/mars_dust_storm.gif

http://antwrp.gsfc.nasa.gov/apod/ap030602.html

http://www.nasa.gov/mov/330028main_close_720p_A.mov

http://science.nasa.gov/headlines/y2003/09jul_marsdust.htm

Because the martian atmosphere is thin--about 1% as dense as Earth's at sea level--only the smallest dust grains hang in the air. "Airborne dust on

Mars is about as fine as cigarette smoke," says Bell.










Mars: Landslide

http://photojournal.jpl.nasa.gov/catalog/PIA10245




Mars: Landslide


The scarp in this image is on the edge of the dome of layered deposits centered on Mars' north pole. From top to bottom this impressive cliff is over 700 meters (2300 feet) tall and reaches slopes over 60 degrees. The top part of the scarp, to the left of the images, is still covered with bright (white) carbon dioxide frost which is disappearing from the polar regions as spring progresses.The largest cloud (upper images) traces the path of the debris as it fell down the slope, hit the lower slope, and continues downhill, forming a billowing cloud front. This cloud is about 180 meters (590 feet) across and extends about 190 meters (625 feet) from the base of the steep cliff.




Mars: Liquid Water

http://www.msss.com/mars_images/moc/2006/12/06/gullies/sirenum_crater/index.html




http://astro.unl.edu/classaction/terrplanets.html



















Mars: Faces On Mars

http://stardate.org/resources/gallery/gallery_detail.php?id=71 http://apod.nasa.gov/apod/ap990315.html


http://stardate.org/resources/gallery/gallery_detail.php?id=71

http://stardate.org/resources/gallery/gallery_detail.php?id=71

http://apod.nasa.gov/apod/ap990315.html


Mars: Deep Holes On Mars


In a close-up from the HiRISE instrument onboard the Mars Reconnaissance Orbiter, this mysterious dark pit, about 150 meters across....Lacking raised rims and other impact crater characteristics, this pit and others like it were originally identified in visible light and infrared images from the Mars Odyssey and Mars Global Surveyor spacecraft. While the visible light images showed only darkness within, infrared thermal signatures indicated that the openings penetrated deep under the martian surface and perhaps were skylights to underground caverns. In this later image, the pit wall is partially illuminated by sunlight and seen to be nearly vertical, though the bottom, at least 78 meters below, is still not visible. The dark martian pits are thought to be related to collapse pits in the lava flow, similar to Hawaiian volcano pit craters.




http://hirise.lpl.arizona.edu/PSP_004847_1745

http://hirise.lpl.arizona.edu/PSP_004847_1745

http://hirise.lpl.arizona.edu/index.php

http://hirise.lpl.arizona.edu/index.php

http://mars.jpl.nasa.gov/odyssey/newsroom/pressreleases/20070921a.html

http://mars.jpl.nasa.gov/odyssey/newsroom/pressreleases/20070921a.html





http://www.nasa.gov/mission_pages/odyssey/images/cave4.html

http://www.nasa.gov/mission_pages/odyssey/images/cave4.html

http://hvo.wr.usgs.gov/gallery/kilauea/erz/devilsthroat.html

http://hvo.wr.usgs.gov/gallery/kilauea/erz/devilsthroat.html

http://hvo.wr.usgs.gov/gallery/kilauea/erz/upper/30424305-044_large.jpg

http://hvo.wr.usgs.gov/gallery/kilauea/erz/upper/30424305-044_large.jpg

http://volcanoes.usgs.gov/Products/Pglossary/PitCrater.html

http://volcanoes.usgs.gov/Products/Pglossary/PitCrater.html

Mars: Martian Meteorites

http://www.psrd.hawaii.edu/July99/EETA79001.html

Splotches of glassy material contain trapped martian atmosphere.Rock is 16 cm across.

Comparison of Viking-measured Mars atmosphere to trapped gases in EETA79001 Shergottite glass. Figure is from Pepin, R. O., 1985, Evidence of Martian Origins, Nature, 317, p. 473-475.





http://www.aerospaceweb.org/question/astronomy/q0193.shtml






The most tantalizing clue found so far came from a meteorite discovered in Antarctica. Named ALH 84001, this hunk of space debris is believed to have been blasted off the surface of Mars about 16 million years ago. The rock survived the perils of space and a fiery trip through the Earth's atmosphere to land in Antarctica some 13,000 years ago.

The meteorite was discovered in 1984, but it was not until 1996 that scientists announced evidence of life in the ancient rock. Though the findings are still controversial, the meteorite contains fossilized remains that could be a primitive form of bacteria. If so, ALH 84001 is the first hard evidence that life of any kind evolved on a planet other than Earth.




http://www.lpi.usra.edu/lpi/meteorites/mars_meteorite.html

http://www.lpi.usra.edu/lpi/meteorites/mars_meteorite.html

Mars’s AtmosphereLACC: §9.3, 9.5, 9.6

• Mars’s surface environment: 95% CO2, 0.007 bars, -67°F (±100+), winds of a few mph, massive (fine) dust storms, wispy clouds

• Mars’s atmospheric evolution = run away refrigerator: low surface gravity (0.38g) means thermal escape of atmosphere; less atmosphere means less greenhouse effect, so temperatures fall; H2O, CO2 condense, so temperatures fall...

• Mars’s clouds: H2O, CO2, fine dust



LACC HW: Franknoi, Morrison, and Wolff, Voyages Through the Universe, 3rd ed.

• Ch. 9, pp. 219-220: 7.

• Study for the test on the Inner Planets (Chapters 6-9)

Due at the beginning of the next class period.

Test covering chapters 6-9 next class period.

Be thinking about the Solar System Project.


Review for the Test 2 of 5:The Terrestrial Planets

[10 pts] Compare and contrast the physical properties of Mercury, Venus, Earth, Luna, and Mars.

• mass, size, density, notable surface features (Caloris Basin, Chicxulub crater, maria, highlands, Tycho, Tharsis Bulge, Olympus Mons, Valles Marineris)

• Interiors: core (inner/outer, (Mercury’s vs Luna’s). mantle, crust); seismic waves

• orbits (distance from the sun, eccentricity, inclination, length of a year) and rotational properties (axial tilt, solar vs. sidereal day, spin:orbit resonance, tide locking)

[10 pts] Understand the processes that shaped the terrestrial planet’s surfaces.

• Collapse of solar nebula, Condensation (frost line), Accretion (planetesimals, differentiation), Heavy Bombardment, Cooling (don’t forget scarps), clearing an orbit of debris

• Tectonic Activity: Core-Interior Heat (radioactive decay), Mantel-Convection, Crust (coronae, ridges and cracks, Plate Tectonics, maria, Valles Marineris)

• Age of planetary surface: radiometric dating (Earth, Luna), number of impact craters, erosion, resurfacing--extensive volcanic activity or plate tectonics

[10 pts] Compare and contrast the atmospheric properties of Venus, Earth, and Mars.

• Composition and Surface Pressure: Venus--90-bar 850°F CO2, Earth--1-bar 59°F N2 (and O2), Mars--0.007-bar -58°F CO2

• Clouds: Venus--H2SO4 sulfuric acid (radar ranging), Earth--H2O water, Mars--H2O water, CO2 carbon dioxide, fine dust

• Temperature--Mercury 797°F to -283°F, Venus 850°F (hotter than Mercury), Earth--59°F average, Moon--257°F to -283°F, Mars-- -67±100+°F

[10 pts] Understand the processes that shape the terrestrial planet’s atmosphere.

• How early atmospheres (CH4, NH3, H2O, CO2) become mature atmospheres (N2 w/ H2O oceans or CO2): outgassing by volcanoes, dissociation by solar uv, thermal escape, liquid water?, condensation

• Greenhouse Effect (Venus--runaway greenhouse, Mars--runaway refrigerator, Earth--just right)

• Evidence and effect of life on the planets (Martian meteorites, oldest fossils, extinction events, O2)

[10 pts] Identify objects from a picture. • Mercury, Venus, Earth, Luna, Mars, Phobos, and Deimos

from space• Venus, Earth, Luna, Mars from the surface• Shield Volcanoes, “Pancake” Lava Domes, Scarps, impact

craters, coronae


A1 09 Venus Mars Atmos

Education

Transcript of A1 09 Venus Mars Atmos