1

HIGHER THAN ADVERTISED

MARTIAN AIR PRESSURE

Part 1: Overview of Pressure Measurement Issues

By David A. Roffman, Embry-Riddle Aeronautical University http://DavidARoffman.Com

Presented at the

14th International Mars Society Convention, Dallas, TX August 4, 2011 (Updated September 9, 2012)

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Accepted

Average Pressure

6.1 Mbar at Mars Areoid

Areoid is Mars equivalent of Sea Level.

Average Earth sea level pressure = 1013.25 Mbar.

6.1 Mbar is nearly a vacuum (= pressure on Earth at 90,417 feet/27,550 meters)

• View from a MIG 25 at 83,600 feet,

• Pressure = ~11.3 mbar

Why Question Accepted Pressure?

Initial stimulus - similarities in Martian & Terrestrial dust devils.

http://www.lpl.arizona.edu/~lemmon/mer_dd/dd_enhanced_587a.gif

Scope of Research: 2 yr. study, special topics course at ERAU, literature & NASA Ames Archives review, interviews of pressure transducer designers, Viking data audit.

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Why Question Accepted Pressure?

Mars dust devils typically have speeds of

6m/s (~13 MPH), but during an Ames experiment at 10 mbar, a wind speed of 70 m/s (~156 MPH) was needed to form a dust devil.

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Why Question Accepted Pressure? 5

Why Question Accepted Pressure?

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• No way to change small dust filters on Vikings, Pathfinder, or Phoenix! Rapid clogging likely.

Only Viking-2 provided published

pressure data for over a Martian year

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Problems with Viking Pressures

When pressures weren’t stuck, they varied with laws for gases in sealed containers (not in contact with the ambient air of Mars).

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First Photo From Mars Shows How

Dust Affected Viking 1!

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Greeley et al. (1992): ”In designing future lander spacecraft for Mars, consideration must be given to the infiltration of fine dust into spacecraft components…” Since dust makes its way in at the air intake tube for the pressure sensor – start there!

Why Question Accepted Pressure?

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Dust storms enormously increase opacity and atmospheric density. Can block 99% of light.

Dust Storm of July 5, 2011

Phoenix, Arizona

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Pressure at nearby Luke Air Force Base increased during the dust storm by 6.6 mbar – that’s more than average pressure (6.1 mbar) at areoid on Mars.

Why Question Accepted Pressure?

Last 4 successful landers long (downrange) by 13.4 - 27 km (request for help from NASA’s Prasun Desai, 2008)

3 landers “lost” might have been short (Mars

Polar Lander & Deep Space 2 in 1999; Beagle 2 in 2003)

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Why Question Accepted Pressure? MPF anemometers could

not be calibrated.

Path

No anemometer on Phoenix. Telltale could not measure speeds >10 m/s and only had 20 - 40% accuracy for winds <10m/s.

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Pathfinder

Windsock mast

MPF Thermal wind sensor

Why Question Accepted Pressure?

Snow. Ice particles in clouds an order of magnitude too small for GCMs – 2 μm vs. 20 to 30 μm (Richardson, et al., 2002)

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DUST DEVILS ARE THE MOST

OBVIOUS WEATHER ANOMALY

If there is so little air on Mars, how can there be enough Δp to generate them at all?

Over 30 dust devils hit

the Phoenix lander in just 150 days.

Pathfinder detected ~79 in 86 days.

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Similarities between Terrestrial and Martian Dust Devils

Seasons (summer on Earth,

spring and summer on Mars)

Electrical properties

(0.8 MV for a terrestrial event).

Shape & often size (but can be 50 x wider and 10 x higher on Mars)

Daily formation times (around noon)

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Similarities between Terrestrial

and Martian Dust Devils

wind speed (6 m/s typical)

core temperature increase (up to 10 K)

dust particle size (1 μm typical). But with low 6.1 mbar pressure, 500 m/s (1,118 mph) wind required to lift 1 μm dust. (Read & Lewis, 2004)

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Differences between Terrestrial and Martian Dust Devils – mainly Absolute and

Relative Pressure Excursions

Maximum pressure drop for a Mars dust devil at Phoenix was ~0.0289 mbar. Max drop at Pathfinder was .0477 mbar.

Pressure drop for a 1953 dust devil that went directly over a microbarograph was 1.354 mbar (13X greater than Pathfinder event, 21X greater than Phoenix d. d.).

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SCALE HEIGHT The pressure acquired by a parcel of air moved up or

down a certain height at a constant temperature.

By scale height math, pressure on Arsia Mons where dust devils occur at 17 km should be about 1.17 mbar.

Again, Ames couldn’t produce a dust devil @ 10 mbar.

p = p0e-(h/h0) where p = atmospheric pressure,

h = height (altitude), P0 = pressure at height h = 0 (surface pressure),

and H0 = scale height.

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Arsia Mons & other Martian Mountains,

Valleys, Landers, and Methane Plumes.

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Spiral Clouds on Arsia Mons (only) look like Hurricane Eye Walls. 1.17 mbar seems too low.

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These clouds extend 15-30 km above the mountain, where scale height calculations indicate pressures of 0.29 to 0.07 mbar. This is like what’s seen for Earth at >34.9 km (>21 miles) above sea level.

NASA web site now does not post the same pressures

as in 1970s. (http://nssdc.gsfc.nasa.gov/planetary/mars/mariner.html)

– Mariner 4 flyby: 4.5 to 9 mbar (old) or 4.1 to 7.0 mbar (new)

– Mariners 6 flyby and 7 flyby: 3.8 to 7.0 mbar (new). However SP-4212 On Mars: Exploration of the Red Planet 1958-1978 (page 243) states of these flyby craft that the: “occultation experiment indicated that the atmospheric pressure at the surface of Mars ranged from 4 to 20 millibars, rather than 80 millibars as estimated earlier.”

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Occultation by Mariners missed

high points (Olympus Mons) and

low points (Hellas Basin).

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Mars Lander Pressure Sensors

Only 4 landers could measure pressure in situ.

None could measure above 18 mbar

(and 2 were limited to 12 mbar).

Limited pressure ranges

based on previous radio

occultation measurements.

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Viking & Pathfinder

Pressure Sensitivity Ranges

3 Tavis pressure sensors sent by NASA: Viking 1 & 2 Range: 0 to 18 mbar

Pathfinder: 0 to 12 mbar on entry, only

6 to 10 mbar at the surface. A 1,034 mbar sensor was also ordered (Tavis CAD

10484 – 1 , but Tavis rep says it remained on Earth) 25

5 to12 Mbar Range Phoenix Dust Filter (Reduced to 0 to 11.5 Mbar for MSL Curiosity)

A Finnish Meteorological Institute report (2009) States that, "We should find out how the pressure tube is mounted in the spacecraft and if there are additional filters etc.“ FMI designed the sensor.

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International Traffic

in Arms Regulations (ITAR)

“After Phoenix landed it appeared that the

actual thermal environment was worse than the expected worse case… Information on

re-location of the heat source had not

been provided initially due to ITAR restrictions.” (Taylor, P.A., et al, 2009)

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“That we at FMI did not know how our sensor was mounted in the spacecraft and how many filters there were shows that the exchange of information between NASA and the foreign subcontractors did not work optimally in this mission!” (Kahanpää [FMI] Personal communication, December 15, 2009)

28 International Traffic

in Arms Regulations (ITAR)

Data Too Similar Year to Year? 55% of same days each year for 4 years VL-1 Pressure was identical.

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PRESSURES DERIVED

BY SPECTROMETER

Similar to VL-1; but

don’t work with ice clouds and frost at poles (Spiga et al., 2007).

Pressure readings published for only 9 days

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COMPARISON OF MARS EXPRESS

SPECTROSCOPY AND VIKING 1 PRESSURES

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Occam's Razor (1) Entities must not be multiplied

beyond necessity.

(2) The simplest solution is usually

the correct one.

The Razor suggests that repeatable Viking pressure data should be believed. However, the consistent Viking-Pathfinder-Phoenix-MSL pressures may only exist because they all had pressure sensor air access tubes clog in similar fashion .

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Why Trash Occam?

OVERALL Viking pressures vary in inverse

proportion to ambient temperature and in

direct proportion to heat required by RTGs to keep internal temperatures stable.

Viking 1 Pressures for Year 1 are 98.19% in agreement with predictions based on Gay-Lussac’s Law. This implies the transducer only measured internal, not external pressures.

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Why Trash Occam?

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Initial MSL daily pressure also varied in inverse proportion to ambient temperature.

Why Trash Occam?

Weather doesn’t match low pressure values

– Dust Devils

– Dust Storms

– Eye walls on huge storms over Arsia Mons

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Why Trash Occam?

No way to change Viking, MPF and Phoenix dust filters that could clog.

Viking data suspicious due to exact repeat over 4 yrs.

Audit of Viking data shows huge patterns of exactly the stuck pressures for up to 6 days

(see Part 2 Presentation). Data shows no justification for continuing the pressure curves.

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WHY TRASH OCCUM?

MRO AEROBRAKING

“At some points in the atmosphere, we saw a difference in the atmospheric density by a factor of 1.3, which means it was 30% higher than the model, but …

around the south pole

we saw an even larger

scale factor of up to 4.5,

so that means it was

350% off of the Mars GRAM model.” Han You, Navigation Team Chief for MRO.

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WHY TRASH OCCAM? MGS Dynamic Pressure Spike @ 121 km Due to

Dust Storms. Pressure Doubles in 48 Hours, Up 5.6 Fold in 4 Weeks.

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Why Trash Occam?

Pathfinder anemometers could not be calibrated.

Phoenix transducer design problems. ITAR at fault. Note: MSL/Curiosity’s 2011 Rover Environmental

Monitoring Station (REMS) was built by the Spanish Ministry of Education with FMI still as a partner. FMI

delivered the MSL pressure sensor to NASA in 2008

(before ITAR problems could be fixed)!

No pressure sensors could measure > 18 mbar (two could only go up to 12 mbar)

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Why Trash Occam?

Landers with a 12 mbar max pressure capability can’t handle a 6.6 mbar pressure increase due to dust storms like that at Luke AFB.

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Why Trash Occam? 41

Difficulty in explaining Barchan

and other sand dune features,

especially in craters on Mars if

pressure is as low as advertised.

Why Trash Occam? 41

http://www.nasa.gov/mission_pages/MRO

"Mars either has more gusts of wind than we knew about before, or the winds are capable of transporting more sand." Nathan Bridges, Planetary scientist, Johns Hopkins University's Applied Physics Laboratory

Why Trash Occam?

Wind-tunnel trials show a patch of sand would take winds ~80 mph to move on Mars (vs. 10 mph on Earth). Viking landers and climate models showed such winds should be rare on Mars.

JPL: Mars Exploration

Rover Spirit detected

shifting sand in 2004.

– Grains of sand dotting

the rovers' solar panels

– Rovers' track marks

filling in with sand.

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IF THE WINDS DID NOT REACH 80 MPH NEEDED TO MOVE SAND, WHAT WERE THEY ON VIKING 1?

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IF THE WINDS DID NOT REACH 80 MPH NEEDED TO MOVE SAND, WHAT WERE THEY ON VIKING 2?

Erasure of earlier spirit

Tracks

Why Trash Occam?

Diurnal pressure max of Viking & MPF (midnight & 1000) don’t agree with Phoenix (0830 & 1530).

Pressures almost always rose 0730 Local Time at VL-1 & 2. Probable cause? RTG heater.

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Cyclic nature of accurate prediction times showed a slow drift as seasons changed

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Why Trash Occam?

NASA Ames failed to simulate dust devils at 10 mbar with appropriate winds

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Where is the full report?

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Links to the most updated Basic Report and all Report Annexes are maintained at http://davidaroffman.com/catalog_1.html

Annexes contain a full audit of Viking pressure data available at

http://www-k12.atmos.washington.edu/k12/resources/mars_data-

information/data.html.

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CONTACT INFO

E-Mail: DavidARoffman@GMail.Com

Website: http://DavidARoffman.com

Slide References Slide 1: http://science.nasa.gov/science-news/science-at-

nasa/2001/ast11oct_2/

Slide 2: 6.1 mbar from: Sherman, S.C. Wu (1977), Mars synthetic topographic mapping, United States Geological Survey, Branch of Astrogeologic Studies, Flagstaff, Arizona 86001, USA

Altitudes from http://www.csgnetwork.com/pressurealtcalc.html

MIG 25 view from http://www.digitalworldz.co.uk/225742-joining-16-mile-high.html

Slide 3: http://www.lpl.arizona.edu/~lemmon/mer_dd/dd_enhanced_587a.gif

Slide 4:

NASA, (2005). NASA simulates small Martian 'dust devils' and wind in vacuum tower. Retrieved from http://www.nasa.gov/centers/ames/research/exploringtheuniverse/vaccumchamber_prt.htm

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Slide References

Slide 5: Reis, D., Lüsebrink, D., Hiesinger, H., Kel-ling, T., Wurm, G., and Teiser, J. (2009). High altitude dust devils on Arsia Mons, Mars: Testing the greenhouse and thermophoresis hypothesis of dust lifting. Lunar Planetary Science. [CD-ROM], XXXII, Abstract 2157. Retrieved from http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1961.pdf

Slide 6: http://www.stevenhobbsphoto.com.au

and 2 mm MPF air tube from Seiff et al. (1997) The Atmospheric Structure and Meteorology instrument on the Mars Pathfinder Lander. http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/15328/Seiff%20et%20al%20JGR%201997.pdf?sequence=1

Slide 7: Top and bottom graphs by Tillman and Johnson as found on page 832 of MARS (1992) edited by Kieffer, H, Jakowsky, B, Snyder, C., and Matthews, M. Middle graph by David and Barry Roffman.

Slide 8: Calculator from http://www.1728.com/gaspres.htm.

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Slide References Slide 9: Greeley, R; Lancaster, N; Lee, S. and Thomas, P. Martian Aeolian

Processes, Sediments, and Features (Chapter 12 of Mars [1992] edited by Kieffer, H.H. et al). Photo from: http://www.nasaimages.org/luna/servlet/detail/nasaNAS~5~5~23140~127274:First-Mars-Surface-Photo

Slide 10: http://www.jpl.nasa.gov/news/news.cfm?release=2007-080.

Slide 11: http://www.nachi.org/forum/f11/awesome-phoenix-dust-storm-62232/

Slide 12: Desai, P.N., (2008) All Recent Mars Landers Have Landed Downrange - Are Mars Atmosphere Models Mis-predicting Density? Third International Workshop on The Mars Atmosphere: Modeling and Observations, held November 10-13, 2008 in Williamsburg, Virginia. LPI Contribution No. 1447, p.9103. http://www.lpi.usra.edu/meetings/modeling2008/pdf/9103.pdf

Slide 13:

Schofield, J.T. et al, (1997). The Mars Pathfinder atmospheric structure investigation meteorology (ASI/MET experiment, Science, 278, 1752-1758

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Slide References

Slides 13: Taylor, P. A., Catling, D. C., Daly, M., Dickinson, C. S.,. Gunnlaugsson, H. P, Harri, A.M., and Lange C. F., (2008). Temperature, pressure, and wind instrumentation in the Phoenix meteorological package, Journal of Geophysical Research,113, E00A10.

http://www.nasa.gov/mission_pages/phoenix/images/press/16613-animated.html

and http://www.atm.ox.ac.uk/main/Science/posters2005/2005cw.pdf

and http://mars.jpl.nasa.gov/MPF/mpf/sci_desc.html

Slides 14: Richardson, M., Wilson, R. J., and Rodin, A. V. Water ice clouds in the Martian atmosphere: General circulation model experiments with a simple cloud scheme, J. Geophys. Res., 107(E9), 5064, doi:10.1029/2001JE0011804, 2002.

Slide 15: Balme, M., Greeley R. (2006), Dust devils on Earth and Mars, Review Geophysics., 44, RG3003,doi:10.1029/2005RG000188.

Slide 16:

Balme, M., Greeley R. (2006), Dust devils on Earth and Mars, Review Geophysics., 44, RG3003,doi:10.1029/2005RG000188.

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Slide References Slide 17: Balme, M., Greeley R. (2006), Dust devils on Earth and

Mars, Review Geophysics., 44, RG3003,doi:10.1029/2005RG000188.

Read, P. L., & Lewis, S. R. (2004). The Martian Climate Revisited, Atmosphere and Environment of a Desert Planet, Chichester, UK: Praxis.

Slide 18: Balme, M., Greeley R. (2006), Dust devils on Earth and Mars, Review Geophysics., 44, RG3003,doi:10.1029/2005RG000188.

Wyatt, R. E. (1954), Pressure Drop on a Dust Devil, Monthly Weather Review, Jan. 1954, pp. 7-8. Retrieved from

http://docs.lib.noaa.gov/rescue/mwr/082/mwr-082-01-0007.pdf

Slide 19: Photo from http://www.space4case.inhetweb.nl/mmw/media/mars2005/tharsismontes9000_20051126_10_1024.jpg

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Slide References Slide 20: Calculations by David A Roffman based on

Smith, D. E., et al. (2001), Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars, J. Geophys. Res., 106, 23,689–23,722, doi:10.1029/2000JE001364. http://www-geodyn.mit.edu/mola.summary.pdf

Slide 21: NASA/JPL/MSSS, (2005). PIA04294: Repeated Clouds over Arsia Mons. Retrieved from http://photojournal.jpl.nasa.gov/catalog/PIA04294

Slide 22: http://nssdc.gsfc.nasa.gov/planetary/mars/mariner.html and http://history.nasa.gov/SP-4212/ch8.html

Slide 23: Kliore, A.J. (1974), Radio occultation exploration of Mars, Exploration of the planetary system; Proceedings of the Symposium, Torun, Poland, September 5-8, 1973. (A75-21276 08-91) Dordrecht, D. Reidel Publishing Co., 1974, p. 295-316.

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Slide References Slide 24: http://www/solarview.com

Slide 25: Personal communications and with a Tavis rep.

Slide 26: Kahanpaa, H., Polkko J., 2009-02-26. The Time Response of the PHOENIX Pressure Sensor, Finnish Meteorological Institute. Doc. No. FMI_S-PHX-BAR-TN-002-FM-99.

Slide 27: Taylor, P.A., Weng, W., Kahanpää, H., Akingunola, A., Cook, C., Daly, M., Dickinson, C., Harri, A., Hill, D., Hipkin, V., Polkko J., and Whiteway, J. (2009). On Pressure Measurement and Seasonal Pressure Variations at the Phoenix landing site, Submitted to Journal of Geophysical Research (Planets).

Vailsala picture adapted from http://www.space.fmi.fi/phoenix/?sivu=instrument.

Slide 28: Personal communication with H. Kahanpää, FMI

Slide 29: J. E. Tillman, University of Washington, Dept. Atmospheric Science

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Slide References Slide 30:

Remote sensing of surface pressure on Mars with the Mars Express/OMEGA spectrometer: 1. Retrieval method A. Spiga, Forget, F., B. Dolla, S. Vinatier, R. Melchiorri, P. Drossart, A. Gendrin, J.-P. Bibring, Y. Langevin, and B. Gondet (2007) Journal of Geophysical Research, 112, E08S15

Slide 31: Remote sensing of surface pressure on Mars with the Mars Express/OMEGA spectrometer: 1. Retrieval method Forget, F., A. Spiga, B. Dolla, S. Vinatier, R. Melchiorri, P. Drossart, A. Gendrin, J.-P. Bibring, Y. Langevin, and B. Gondet (2007) Journal of Geophysical Research, 112, E08S15

J. E. Tillman, University of Washington, Dept. Atmospheric Sciences

Slide 34: http://www.spaceflight101.com/msl-rems-science-reports.html.

Slide 36: http://davidaroffman.com/VL2%20STUCK%20PRESSURE%20GAUGE%

20639%20to%20799.pdf.

Slide 37: http://www.universetoday.com/2006/09/21/aerobraking-mars-orbiter-surprised-scientists/

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Slide References Slide 38: Johnston, M.D., Esposito, P. B., Alwar, V., Demcak, S. W., Graat,

E. J., & Mase, R. A. of the Jet Propulsion Laboratory, California Institute of Technology, Mars Global Surveyor Aerobraking at Mars, 1998

Slide 39: http://www.atm.ox.ac.uk/main/Science/posters2005/2005cw.pdf and

http://starbrite.jpl.nasa.gov/pds/viewInstrumentProfile.jsp?INSTRUMENT_ID=WINDSOCK&INSTRUMENT_HOST_ID=MPFL

and http://en.wikipedia.org/wiki/Mars_Science_Laboratory

and http://space.fmi.fi/solar.htm

Slide 40: http://www.jpl.nasa.gov/news/news.cfm?release=2007-080.

And http://www.universetoday.com/2006/ http://www.universetoday.com/2006/

Slide 41: Greeley, R; Lancaster, N; Lee, S. and Thomas, P. Martian Aeolian Processes, Sediments, and Features (Chapter 12 of Mars [1992] edited by Kieffer, H.H. et al). Mars photo from http://lightsinthedark.wordpress.com/2011/01/26/beautiful-barchans/

Namibian and Moroccan dunes from http://www.bukisa.com/articles/44523_worlds-most-amazing-cliffs-and-fascinating-dunes

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Slide 42: http://www.nasa.gov/mission_pages/MRO

Slide 43: http://sci.esa.int/science-

e/www/object/index.cfm?fobjectid=49342.

Slide 44: http://www.agu.org/pubs/crossref/2008/2008JE003101.shtml

Slide 45:http://www.agu.org/pubs/crossref/2010/2010JE003674.shtml

Slide 49: http://oregonexplorer.info/craterlake/facts.html

and Water ice in Vastitas Borealis Crater (Credit: European Space Agency / ESA/DLR/FU Berlin [G. Neukum])

Spare Slides If Needed Slide 60: Calculations based on heights (except for Phoenix

lander) given by David E. Smith et al. 2001

Slide 61: Schofield, J.T. et al, (1997). The Mars Pathfinder

atmospheric structure investigation meteorology (ASI/MET experiment, Science, 278, 1752-1758

Slide 63: http://sci.esa.int/science-e-media/img/be/MEx_water_vapour_animation_400.gif

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SCALE HEIGHTS FOR MARTIAN

MOUNTAINS AND VALLEYS (Page 7 of Roffman Basic Report for HIGHER THAN ADVERTISED MARTIAN AIR PRESSURE)

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Pathfinder Pressure Uncertainties

The (pressure) variation seen by Pathfinder …

The amplitude of the diurnal tide is sensitive to the

calibration of the pressure sensor, which is still preliminary

(Schofield, et al., 1997)

May explain why the Pathfinder anemometers could not be calibrated, however the wind socks were supposed to only move when winds topped 5 m/s. Cameras had to be working. The

thermal wind sensor had other problems.

Less than 12 wind measurements reported.

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Why Trash Occam?

http://sci.esa.int/science-e-media/img/be/MEx_water_vapour_animation_400.gif 62

SPICAM spectrometer on ESA's Mars Express spacecraft reveal Mars air is supersaturated with water vapor (29 Sep 2011).

Previous models underestimated H2O at heights of 20–50 km.

10 to 100 times more H2O than expected at this altitude. Partial pressures imply denser air too.