Martian Dust Devil Gedanken Experiment (Updated 2/14/2012)

HOME PAGE Web Site Contents Mars Report Contents Mars Report Abstract CV for Dr. David Roffman Diplomas PhD Thesis PhD Thesis Powerpoint Mars PowerPoint MSL Weather Reports MSL Weather Fall Yr 3 MSL Yr. 3 Summer Weather MSL Yr. 3 Spring Weather MSL Ultraviolet Desai, EDL, Parachutes & ExoMars Mars winter vs. summer temps Sea at Utopia Planitia, Mars Tree Stump at MSL? Spherical life on Mars? Mars Report Abstract, 1-1.2 Mars Report Sec.2-2.1 Report 2.2-2.4 Report 2.5-2.5.2 Report 2.5.3-2.7 Report 3-4.1.2 Report 5 to 6 Report  7-7.2.1 Report 8-9 Report 10-11 Report  12-12.2 Report 12.3-12.5 Report 13-14 Report 14.1 Report 14.2-14.3 Report 14.4-14.6 Report 15-18 Report Afterword Report References Rebuttal of REMS Report Running water on Mars MSL Year 1 Weather MSL Yr 2 Winter-Spring Weather MSL Yr 2 Summer Weather MSL Yr 2 Fall Weather MSL Yr 2-3 Winter Weather Adiabatics MSL Hi Temps MSL Low Temps Organic Chem found by MSL Oxygen in Mars Air MSL Day length & Temp Warm winter ground temps 155-Mile High Mars Plume Radiation Diurnal Air Temp Variation Mars Temps Fahrenheit Beagle found JPL/NASA Pressure Mistakes Enter MarsCorrect Sol 370, 1160 & 1161 Histories Mars-Radio-Show JPL Fudges Pressure Curves MSL Temp. ∆ Mast to Ground High & Low Pressures Normalized Mars soil 2% water Moving rock Mars MAVEN MSL Relative Humidity Claim Ashima Concedes Original MSL Weather Record Old MSL Weather Record MSL Summer Weather Pressure Estimate REMS Wind MSL Pressures REMS Reports Curiosity Geology CERN-2013-pics Daylight Math MSL Errors P1 MSL Errors P2 MSL-Chute-Flap MSL daylight Ashima Sols 15 to 111 Ashima Sol 112 to 226 Ashima Sol 227 on New Ashima Sols 270+ MSL Summer to Sol 316 Weather Forecast Wind Booms MSL Credibility MSL Temp. Swings MSL Temperatures Sample Analysis at Mars (SAM) VL2 - MSL Ls Comparson Ashima MIT Mars GCM Dust Storm Nonsense Mars Slideshow Moving Sand & Martian Wind 3 DEC12 Press Conf. MSL Press Conf. 15NOV2012 Sol Numbering MSL Pressure Graph to Ls 218.8 MSL Sky Color Mars Sky Color DATA DEBATE! Zubrin's Letter Phoenix Vaisala Vaisala Pressure Sensors Phoenix &MSL Flawed MSL REMS Viking pressure sensors failed MSL landing site Mars Landings Phobos Grunt Martian Air Supersaturation Martian Secrets? Mars & CH4 Mars and MSL Time Viking Pressure Audit Links Mars Society 2008 Quant Finance Frontiers Home Front. Preface Frontiers Ch. 1 Frontiers Ch. 2 Antimatter Lightning Frontiers Ch. 3 Frontiers Ch. 4 Frontiers Ch. 5 Frontiers Ch. 6 Frontiers Ch. 7 Frontiers Ch. 8 Frontiers Ch. 9 Frontiers Ch 10 Frontiers Ch 11 Frontiers Ch 12 Frontiers Ch 13 Frontiers Ch 14 Frontiers Ch 15 Frontiers Ch 16 Frontiers Ch 17 Frontiers Ch 18 Frontiers Ch 19 Frontiers Ch 20 Frontiers Ch 21 Frontiers Ch 22 World Tour Spring-Break -13 Other Travels Asteroid Impact? ExoMars data Unit Issues Viking Pressures Tavis CADs Landing Long Scale Heights LS of Max/Min Pressures Tavis Report Tavis Failures Lander Altitude Martian Trees? Code Experiment Gedanken Report Mars Nuke? Martian Flares Mach Numbers MOLA (altitude) Original Mars Report Mariner 9 & Pressure Mars  Temps MSL Time MPF Pressure Blog Debates Spring Pendulum Plasma Model Reporting Errors Orbital Parameters Anderson Localization P. 1 Anderson Localization P. 2 Moving rock old Navigating Mars Mars Report Section Links Mars Report Figure Link Gillespie Lake rock outcrop MSL Sol 200 Anomaly Sol 1300&1301 Anomalies Gilbert Levin & Labeled Release Brine on Mars Ceres Lights Yr 1 Table 1 amfivan Missing data Mitchell Report Old Mars Report All MPF Temps ExoMars fails Did Spirit find past life? MSL ground temps go haywire Seasonal Pressure Altitude Calculations

Note: A technical report to sum up this page is being developed and posted on my site at Mars Report  The report is far more complete, up to date, and organized than this page is.  This page was used to develop the technical report.  If you have limited time, please read the report.  This page, however, remains posted because it has useful links not included in the report.

 

 

ABSTRACT

 

Viking, MPF and Phoenix pressure transducers likely clogged with dust and failed on landing. They probably measured internal, but not ambient air pressure.  No landers employed any way to clean or replace dust filters. This explains the enigma of dust devils/storms on Mars with a pressure (incorrectly) rated at 6.1 mbar at areoid. This report combines an extensive audit of pressure records with NASA-archived historical documents, and personal interviews of pressure transducer designers. Both Vikings often showed consistent pressure spikes daily at the same time. They were highly correlated with how the pressure of a gas in a sealed container would vary with the Absolute temperature.  Annual Viking pressures swings are shown to be likely caused by increased heating by the radioisotope thermoelectric generators (RTGs). A simple formula, Pressure predicted = (6.51 mbar*255.77 K)/Temperature K measured, was very often consistently correct (< 2% difference) for predicting the pressure measured at any given hour.

Problems with pressures derived by radio occultation experiments are discussed, as are failed Pathfinder anemometer calibration efforts and the lack of an anemometer on Phoenix. The Phoenix transducer suffered from confusion by designers about dust filter location, and lack of information about nearby heat sources due to International Traffic and Arms Regulations. Further pressure questions arise from high densities encountered during aerobraking operations (particularly over the South Pole). Spectroscopy for pressure did not work over ice there. NASA could not replicate dust devils at 10 mbar without employing wind speeds 11+ times greater than associated with Martian dust devils, yet dust devils and spiral clouds with ~10 km wide eye walls are seen on and over Arsia Mons where pressure was thought to be ~1 mbar. Future transducers require much wider pressure range sensitivity and a way to replace dust filters and keep air access tubes clear. 

 

 

PROBLEM STATEMENT.  An effort was made by NASA at the Ames Research Center to simulate Martian dust devils at a pressure of 10 mbar, but the wind speeds required by the apparatus (70 meters per second) were over 11 times higher than actual recorded Martian dust devil wind velocities seen (6 meters per second) by landers (Pathfinder and Phoenix) on Mars (see the discussion at the end of this web page).  NASA was unable to replicate the dust devil with a fan spinning at the 10 mbar pressure level.  This gedanken (thought) experiment will use available data points on Earth (St. George, Utah) and Martian dust devils, photographs, and the Ames Experiment to test NASA lander indicators pointing to an average surface pressure on Mars in the 7.5 mbar range.  As will be discussed below, under High Altitude Martian Dust Devils,  many dust devils have even been reported on a Martian mountain (Arsia Mons) where ambient pressure is supposedly only 1 mbar. 

 

DATA

The left graph above shows the surface pressure as a dust devil passes by the Mars Pathfinder. The pressure varies between just over 6.7 mbar to about 6.74 mbar.  Average pressure at sea level on Earth is 1,313.2 mbar (compared to somewhere between 6 to 10 mbar on Mars) which (on Earth) equals 760 Torr (mm of mercury, which is about 29.92 inches of mercury).  Also see the discussion on Martian dust devils at the Phoenix landing site.  It states that the typical vortex has a diameter of 150 meters, and extends up to 1 kilometers, but some go as high as 10 kilometers.  Vortex wind speeds are 6 meters per second (13.4 miles per hour), the core pressure drops are (on) order of 1 Pascal (Pa), and the temperature rises are up to 10 K.  Curiously, the Phoenix results on the right graph above show a pressure drop from about 842.5 Pa (8.425 mbar) to about 842.2 Pa (8.422 mbar). Elsewhere the article states that the pressure drop is 1.9 to 3.2 Pa if dust is to be raised.  The article admits that the response time of the sensor is 3-5 seconds, which may not capture peak pressure perturbations.  Note: 100 Pascals (1 hectopascal) = 1 millibar (mbar)

PRESSURE UNITS.  For an on-line calculator that converts pressure units from one system to another, see Lenntech Pressure Converter.  It offers conversions for the following units: bar, atmospheres (1 = standard atmosphere on Earth), Pascals, Torr (mm Hg), mm of water, kg per square cm, pounds per square foot, and pounds per square inch.  Left off: inches of mercury (Hg) and mbar. To find or use mbar or inches of mercury, we must resort to line equation conversion problems or other on-line calculators.

COMPARISONS WITH A SMALL DUST DEVIL ON EARTH.  Roy E. Wyett of the Weather Bureau Regional Office in Salt Lake City, Utah reported that a small, approximately 50 foot high, 50 to 60 foot wide dust devil had its center pass within 8 to 10 feet of a microbarograph on August 12, 1953 in St. George, Utah. A decrease of 0.04 inch of mercury was recorded.  This equals a drop of 276 Pa (2.76 mbar).  Again, this is compared to an alleged pressure drop seen by Mars Pathfinder of about 0.04 mbar or 4 Pa.  The Phoenix Mars Lander figures above were just 1.9 to 3.2 Pa. Yet the Martian dust devils can go  up to 1 kilometer.

COMPARISONS WITH TORNADOES ON EARTH.  The most powerful dust devil recorded by Mars Express Orbiter between January 2004 and July 2006 had a speed of 59 m/s (132 mph).  This is comparable in speed to an F2 tornado which causes considerable damage at atmospheric pressures found on Earth.  However, if the Martian atmospheric pressures are as low as advertised, these storm would not be so worrisome.  How much does pressure drop in a tornado on Earth?  The engineering team at Texas Tech's Institute for Disaster Research (Minor et al., 1977) point out that the pressure drop inside a tornado with 260 mph winds is only about 10%, or just 1.4 pounds per square inch.  This would be at the upper end  of the range for an F4 tornado.  1.4 pounds per square inch is equal to 9,800 Pascals (average Martian atmospheric pressure of 7.5 mbar equals 750 Pa).  So the pressure drop in an Earth F4 tornado is 13 times greater than the entire alleged air pressure on Mars.  But Mars only has dust devils seen so far at the F2 level of wind speed (113-157 mph).  As stated during a CNN interview by storm chaser Tim Samaras, "the pressure actually correlates directly with the wind speed."  If so, we might well expect that a 130 mph F2 tornado on Earth would still show a pressure drop that would be 6 or 7 times greater than the entire average pressure asserted for Mars.  This again begs the question, how can such speeds be achieved in Martian dust devils with such a small air pressure to start with?  Again the instrument figures from Mars appear to contradict common sense.

PRESSURE DROP ON MARTIAN DUST DEVILS IN VARIOUS UNITS:

Range of 0.3 Pascal to 3.2 Pascal*

Range of 0.003 mbar to 0.032 mbar

An on-line unit converter indicates 0.3 Pascal = 0.0000885899 inches of Mercury. 

The same converter indicates that 3.2 Pascals = .000944959458 inches of Mercury.

Size of Mars Events:

Heights = up to 8 or even 10 kilometers.

Width = 150 meters = 492 feet

 

 

PRESSURE DROP IN UTAH DUST DEVIL IN VARIOUS UNITS:

.04 inch of mercury(26.98 down to 26.94 inches of Mercury)

1.016 Torr

1.016 mm Hg

1.3447 mbar

134.47 Pascal

Size of Utah Event:

Height = 50 feet high

Width = 50-60 feet wide.

Airport Elevation: 2,941 feet.

 

 *Note: Balme and Greeley report that Mars Pathfinder "identified 79 possible convective vortices from MPF pressure data and recorded pressure drops from ~0.5 to ~5 Pa (~0.075% to ~0.75%).  Over half of these encounters had pressure drops less than 1 Pa with relatively few "large" or intense (possibly dust loaded) vortices."  The Utah dust devil showed a drop from 26.98 to 26.94 inches, which is a 1.48% drop.  This percent drop is between 1.973 (1.48/.75) to 19.73 (1.48/.075) times greater than what was seen by Mars Pathfinder.  So we are asked to believe that incredibly small absolute and percent pressure drops on Mars are producing almost the exact same storms that we see on Earth.

 

 

Here is a table that gives the atmospheric pressure at various altitudes for Earth.

 

Altitude in Feet        Pressure in Inches of Mercury            

    0,000                 29.92              
    1,000                 28.86              
    2,000                 27.82              

    3,000#               26.82              
    4,000                 25.84              
    5,000                 24.89

  10,000                 20.58                             
  15,000                 16.88              
  18,000 *              14.94            

  20,000                 13.75

  25,000                 11.10

  30,000                 8.886

  35,000                 7.041

  40,000                 5.538

  45,000                 4.355

  50,000                 3.425

  60,000                 2.118

100,000                 0.329 This equals 11.141mbar. Thus the 6 to 10 mbar pressures normally assigned to the Martian atmosphere are equivalent to pressures in the Earth's atmosphere that are found here in excess of 100,000 feet.  However, not all online calculators agreed.  One gave the pressure at 100,000 feet to be about 2.2 mbar, and indicated that 10 mbar was equivalent to an altitude of 84,998 feet which is 16.098 miles.

 

* This is almost exactly one-half the sea-level value.

#Very close to the 2,941 foot altitude at St. George Municipal Airport.

 

MARTIAN ATMOSPHERIC GASES: 

 

Viking atmospheric measurements

Composition

   95.32%
   2.7%
   1.6%
   0.13%
   0.07%
   0.03%
   trace

   carbon dioxide
   nitrogen
   argon
   oxygen
   carbon monoxide
   water vapor
   neon, krypton, xenon,
   ozone, methane

Surface pressure

   1-9 millibars, depending on altitude;
   average 7 mb

 

DUST DEVIL CORE TEMPERATURE INCREASES. 

UP TO 10OC TEMPERATURE RISE ON THE MARS DUST DEVILS.  Note: In a 22-page article (in Review of Geophysics, 44, RG 3003/2006) by Matt Balme (of the Planetary Science Institute, Tucson, AZ) and Ronald Greeley (Department of Geological Sciences, Arizona State University, Tempe, Arizona) entitled Dust Devils on Earth and Mars, we read of terrestrial dust devil cores that, “Temperature excursions <10o C are found consistently, but measurements with an order of magnitude higher sampling rate show temperature excursions as great as 20o C.” . The table below summarizes the terrestrial studies just cited from the Balme and Greeley paper.  It indicates an average terrestrial dust devil core temperature increase of about 10.8 degrees Celsius.   Similarity of core temperature increases of Martian and terrestrial dust devils might serve as more evidence that the ambient pressures on Mars are not as different from Earth as NASA contends. 

 

A

B

C

D

E

F =C*E

F TOTAL/B TOTAL

TERRESTRIAL DUST DEVIL

STUDY

N

MINIMUM TEMP INCREASE

MAXIMUM TEMP INCREASE

MEAN TEMP INCREASE

DEGREES C

 

 

SINCLAIR 1964

4

4

8

6

24

 

SINCLAIR 1973

3

3.5

5

4.25

12.75

 

METZGER 1999

~20

8

22

15

300

 

TRAIT EL AT 2003

5

1

3

2

10

 

TOTAL

~32

 

 

 

~346.75

 

MEAN TERRESTRIAL

DUST DEVIL

CORE TEMP INCREASE

 

 

 

 

 

~10.8359375

 

 

DIURNAL ACTIVITY: FREQUENCY OF MARTIAN & TERRESTRIAL DUST DEVILS.  About 80 convective vortices were recorded by Mars Pathfinder.  Most occurred between 1200 and 1300 local time [Murphy, J., and S. Nellis (2002), Mars Pathfinder connective vortices: Frequency of occurrences, Geophy. Res. Lett., 29(23, 2001, doi: 10.1029/2002GL015214].  This matches what is seen on Earth.  If the air pressure differences were as great as advertised it might be hypothesized that it would take longer to heat the air over the Martian ground where these storms are generated.  As is seen in time-lapse photography from the Mars Exploration Rover Spirit, dust devils are very common events on Mars.  While it is true that dust devils may deposit the bulk of the dust responsible for the color of the Martian sky, it is also alleged that dust devils might cause up to two thirds of all windblown dust for particles under 25 microns in the U.S., and that in the U.S. southwest and elsewhere they could be a major cause of poor air quality [Gillette, D.A., and P.C. Sinclair (1990), Estimation of suspension of alkaline material by dust devils in the United States, Atmos. Environ. Part A, (245), 1135-1142].

 

SNOW ON MARS

  The Phoenix link provided in the first paragraph led to time-lapse photography and an indication that it might snow.  Another Phoenix article indicates that Phoenix found it does indeed snow on Mars at night. For reference, it snows at the Earth's south pole, but annual snow there is under one inch.

 

COLOR OF THE MARTIAN SKY:  Although initial pictures from Viking showed a blue sky on Mars, after corrections were made, it was generally given as butterscotch or pink during the day, but blueish at sunset.  At times there have been questions about computer interpretations of data that may have affected color.  For a blue take, see the image by Roel van der Hoorn.  The  color of the sky may vary with the amount of dust injected by dust devils.

 

MARTIAN LANDING COORDINATES:  To find specific sites on Mars, you can now use Google Mars.  The landing sites for Mars rovers are given below:

 

LANDER

DATE LANDED

LATITUDE

LONGITUDE

VIKING 1

JULY 20, 1976

22.697 O NORTH

48.222 O WEST

VIKING 2

SEPT. 3, 1976

48 O NORTH

226 O WEST

PATHFINDER

JULY 4, 1997

19.13O NORTH

33.22O WEST

SPIRIT

JAN 4, 2004

14.5718 O SOUTH

175.4785O EAST

OPPORTUNITY

JAN 25, 2005

1.95 O SOUTH

254.47O EAST

PHOENIX

MAY 25, 2008

68O NORTH

234O EAST


 

Photo below: Dust Devil on Mars

DO UNITS DRIVE THE PROBLEM?

One possibility is that somebody who designed the pressure instruments screwed up on the units.  Does this also sound crazy? As MSNBC reported, "the Mars Climate Orbiter, which... disappeared just as it arrived at Mars... in 1999. NASA later released the story that the probe was lost because some low-level workers mixed up English and metric units for rocket thrust. This became a big public joke, and deflected attention from the true cause.  Blaming the foul-up in units was a misrepresentation: To save money, NASA had deleted staffing levels to double-check work, assuming instead that all the workers would make no mistakes."

      The Mars Climate Orbiter was intended to enter orbit at an altitude of 140.5–150 km (460,000-500,000 ft.) above Mars. But Lockheed Martin, the NASA Contractor, used imperial units (pounds-seconds) instead of the metric system.  This caused the spacecraft to dip to 57 km (190,000 ft.). It was destroyed by atmospheric stresses and friction at this low altitude. Evidently, though surface pressure/atmospheric density for Mars is supposed to be very low, even at 35.98 miles high, there is still enough air to bust up a probe at a slower entry speed than would be used on Earth (velocity required for a circular orbit of Mars is only 3.4 km/sec compared to the 7.7 km/sec of a space shuttle in orbit around Earth). 

     So maybe somebody failed to double check the units again on the two types of pressure instruments used by the 4 landers that took pressure readings. In fact, many countries use a comma where most Americans use a decimal point.  This includes Finland, which developed the 26-gram pressure sensor for the Phoenix lander. With international staffs and instrumentation vendors, commas rather than decimal points provide more opportunity for critical errors.  Such an error here could cause a world that might support higher life to look much too hostile for that purpose without radical, expensive, and very long term terraforming efforts.

Countries using Arabic numerals with decimal point

http://upload.wikimedia.org/wikipedia/commons/thumb/8/83/DecimalSeparator.png/250px-DecimalSeparator.png


Decimal Separators:
Dot — Blue
Comma — Green
Non-West-Arabic Numerals — Red
Unknown — Grey

 

Nations that are involved with space research where a dot is used to mark the radix point include the United States, Australia, Canada (English speaking) People's Republic of China, India, Sri Lanka, New Zealand, Israel, Japan, South Korea, and Switzerland.

Nations that are involved with space research where a decimal comma is used to mark the radix point include Belgium, Brazil, Bulgaria, Canada (French Speaking), Costa Rica, Denmark, Finland (where the pressure sensor for the Phoenix lander was built), Hungary, Italy, Kazakhstan, Latvia, Lithuania, Luxembourg, Poland, Romania, Russia, South Africa, Spain, Sweden, Turkey, and Ukraine.  Where scientists intermingle in space programs, there is the potential for human error in interpreting results or planning when different methods are being used to express the same numbers.

Below: Dust Storms are not to be confused with Dust Devils are Mars. The storms are global in nature, while the dust devils are local events.

Brief Description

Below: Dust Devils have even been reported on the Arsia Mons volcano on Mars at altitudes of 17 kilometers where air pressure us supposed to be only 1 mbar.

HYPOTHESIS:  Dust devils require a certain pressure to form, and they exist on both Earth and Mars.  If Mars has almost no atmospheric pressure, the low differences between ambient air pressure and dust devil core pressures shouldn’t be able to lift the dust on Mars.  Therefore, the pressure on Mars may be higher than is reported.  Errors in reporting may be due to problems associated with unit conversion or lander equipment design. 

    Until Phoenix landed in 2008, the only landers carrying dedicated meteorology instruments were Vikings 1 and 2 plus the Mars Pathfinder. There was little wind speed data  for Mars because of calibration problems with the wind sensor for Pathfinder [Schofield, J.T. et al, (1997) The Mars Pathfinder atmospheric structure investigation meteorology (ASI/MET experiment, Science, 278, 1752-1758].  Of course, if basic assumptions about  air pressure on Mars were not correct, they might actually have caused the wind sensor calibration problem.  The only known problems associated with Viking pressure sensors so far include too low a sample rate  to detect vortices [Ryan, J.A,, and R.D. Lucich (1983), Possible dust devils, vortices on Mars, J. Geophys. Res., 88, 11.005-11,011].

   For Mars Pathfinder, pressure was measured by a Tavis magnetic reluctance diaphragm sensor similar to that used by Viking, both during descent and after landing.  Thus, if the original design was flawed, the error would be repeated on Pathfinder!  While successive mission failures due to the same parts are rare, they do happen.  An example would be the two “off nominal” re-entries in 2007 and 2008 of Soyuz TMA-10 and 11which involved separation failures on the modules, thus initiating the ballistic return for their three person crews.  The most likely cause then was repeated failure of an 8 X 55 explosive bolt.

     The Phoenix lander in 2008 also carried a meteorological station.  However, it carried a 26-gram instrument developed by the Finish Meteorological Institute.  The device is based on the Vaisala Oy sensor technology and components for the instrument which was delivered by the Micro Analog Systems Oy and Selmic Oy. 

     An error for the new Finish instrument could be due to design or programming flaws based on previous assumptions, or even something as simple as the fact that Finland uses a comma rather than a dot to mark the decimal radix point (see the discussion above under Do Units Drive the Problem?).  It is true that the comma problem would likely lead to an error of 3 orders of magnitude rather than 2, but it's also true that dust devils are common on Arsia Mons where pressure should only be about 1 mbar, at best.  The issue here  to investigate was what is the range of pressures that the Finish unit is designed to measure?  The answer (learned on 10/26/09) is just 5 to 12 mbar. While this is in line with Viking and Mars Pathfinder readings based on a Tavis instrument, it is not a wide enough range to let us know if the Tavis readings were flawed. 

 

EXPERIMENT:  My original concept was to test the error hypothesis, by constructing a vacuum chamber.  The Martian atmosphere can be simulated by decreasing pressure in the chamber (from Earth norm of 1 atmosphere - 1013.25 mbar) down to between 7 and ten mbar (as written in Dr. Zubrin’s, The Case for Mars).  Then dust that is the same composition as Martian dust (1 to 5 micrometers according to NASA) can be placed on the ground of the chamber.  Finally, with wind speed and pressure instruments in place, a swirling wind (generated by a fan) will be created to model the Martian dust devil phenomena.  However, I later learned that NASA had essentially done exactly what I had proposed to do, but had required winds so great to generate the dust devils that their fan was inadequate to get the job done.  Frankly, this fact alone seemed to confirm my suspicions that Martian atmospheric pressures must be greater than advertised. 

      If the physical experiment is repeated to check for errors in design, factors to match with advertised values for Mars should include:

   1.  Temperatures.  The average recorded temperature on Mars is -63 °C (-81 °F) with a maximum temperature of 20 °C (68 °F) and a minimum of -140 °C (-220 °F).

   2.  Humidity.  Martian relative humidity varies from 100% at night to nearly 0 (about 0.3%) during the day.  It is assumed here that the dust devils are created mostly during the day on Mars, and that humidity can therefore be kept low during the experiment.

   3.  Atmospheric gas composition.  The gas allowed in the vacuum chamber should mostly be carbon dioxide to match Martian conditions.

    4.  Particle charge.  There have been reports of high voltage in association with Martian dust devils.  A difference in potential would be required between the top and bottom of the simulated dust devil to replicate this factor.  

     Pressure drops (and % drops) in the vacuum chamber should compared to data from our Mars landers, and with drops seen in the St. George, Utah event.  If this experiment, under pressure and other conditions similar to Martian values, creates a dust devil that is very similar to those seen on Mars; then NASA assertions about Martian pressure are substantiated.  But if no dust devil is created with the pressure in the 6 to 10 mbar level, then the implication would be that Martian pressures must be higher.  Pressure could then be slowly increased in a pressure chamber until the threshold for dust devil formation is attained and recorded.  Likewise, as dust devils have been reported on Martian mountains where pressure is lower, a pressure chamber could be used to determine the lowest limit in those conditions.

Figure below: Dust devils on Arsia Mons

HIGH ALTITUDE MARTIAN DUST DEVILS.  

Dust devils have been observed on Mars on Arsia Mons at altitudes of about 17 kilometers.  These events require wind speeds of 30 meters per second (about 67 miles per hour).  Such winds are found locally on Mars, but wind speeds are typically much lower.  The Instuitut fur Planetalogie in Munster, Germany reports that 28 active dust devils were reported in their study region (236.5 - 243 degrees East, 14.5 degrees South) on Mars, with eleven of them at altitudes higher than 16 km, and most inside the caldera of Arsia Mons (see image on the left above).  The others dust devils were at elevations ranging from 7 to 12 km.  They estimate air pressure for the higher events at 1 mbar, and state up front that they don't fully understand how particles that are a few microns in size can be lifted.  Indeed they state that 1 mbar  "requires wind speeds 2-3 times higher than at the Mars mean elevation for particle entanglement."  Obviously, 1 mbar is a considerably lower pressure than the 10 mbar used by NASA Ames when it failed to recreate dust devils with a fan alone in a vacuum chamber (see the Discussion below).

 

Arsia Mons Dust Devils Compared to Terrestrial Snow Devil Formation

 

Although more air pressure that 1 mbar would seem to be necessary for dust devils to form in a manner like snow devils do on Earth, when considering how dust devils form on Arsia Mons, its great height and irregularities at the top of the caldera may suggest a similar manner of formation.  When wind flows past an obstacle, the air can develop a short vertical eddy that spins off downwind. The larger the obstacle and the stronger the wind speed, the greater the chance a large snow devil will form on Earth.  This might explain what we see inside the caldera on Arsia Mons.  See Bryan Wilson’s comments from the Mount Washington Observatory.

WIND SPEEDS ON MARS


 

     Just how fast can winds move on Mars according to NASA?  Well, their Mars Team Online states that, "Martian surface winds are normally quite light (between about 4 and 15 miles per hour [6.5 to 24 km/hour]). On occasion, however, surface winds gust to about 50 miles (80 km) per hour and, during dust storms can blow at over 300 miles (480 km) per hour. Because the Martian atmosphere is so thin, however, you would feel much less pressure from the wind than if you stood in a similar speed wind on earth."  There, however, is a huge difference between a dust storm and a dust devil.  Dust storms can envelope the entire planet on Mars. 

    An article entitled Dust devil speeds, directions of motion and general characteristics observed by the Mars Express High Resolution Stereo Camera asserts that dust devil velocities were directly measured from orbit, and range from (only) 1 meter per second to 59 m/s.  These velocities convert to 2.237 miles per hour on the low end to 132 miles per hour on the high end.  Even on the high end, we do not see the 70 m/s (156 miles per hour) required by the Ames apparatus.  Of note, this article suggests that dust devils make a significant contribution to the dust entrainment into the atmosphere and to the Martian dust cycle. This assertion is based on the study’s  “combining the dust-lifting rate of 19 kg/km 2/sol derived from the Spirit observations with the fewer in number but larger in size dust devils from various other locations observed by (the High Resolution Stereo Camera) HRSC.”



Discussion

 

1. PAST NASA DUST DEVILS EXERIMENTS. 

 

     NASA has already run experiments that attempt to simulate dust devils on Mars.  However, the article just linked to states that, “The simulated Martian atmosphere in the wind tunnel is so tenuous that a fan would have to spin at too high a speed to blow thin wind through the test section. The high-pressure air draws thin air through the tunnel like a vacuum cleaner sucks air. Scientists also compare this process to a person sucking water through a straw. The resulting simulated Mars wind moves at about 230 feet (70 meters) per second.”  This is a much higher speed (over 11 times faster) than the 6 meters per second cited above for the Phoenix landing site.   Seventy meters per second is 156.8 miles per hour, the strength of a category 5 hurricane), and nearly the strength of an F-3 tornado (158 to 206 MPH).  Further, the acknowledgement that the air is too thin at (the 10 mbar pressure used) to get the spinning through the means of a fan would seem to lend credence to the idea that something is incorrect about the 10 mbar pressure on Mars.  There are also indications that there may be high voltage electric fields associated with Martian dust devils.  If so, this would also mirror terrestrial dust devils, where estimates are as large as 0.8 MV for one such event [Farrell, W.m., et al (2004), Electric and magnetic signatures of dust devils from the 200-2001 MATADOR desert tests, J Geophs. Res., 109, E03004, doi: 10.1029/2003JE002088]. 

 

2. THE PROBLEM OF MARTIAN DUST <2 MICRONS  AND WIND SPEEDS   

 

     Balme and Greeley write that, “The Martian atmosphere is thinner than Earth’s… so much higher wind speeds are required to pick up sand or dust on Mars.  Wind tunnels studies have shown that, like Earth, particles with diameter 80-100 μm (fine sand) are the easiest to move, having the lowest static threshold friction velocity, and that larger and smaller particles require stronger winds to entrain them into the flow.  However, much of Mars’ atmospheric dust load is very small (<2 μm [Pollack et al, 1979, 1995; Smith and Mars Pathfinder Team, 1997; Tomasko et al., 1999; Lemmon et al., 2004]), and the boundary layer wind speed required to entrain such fine material are in excess of those measured at the surface [Hess et al., 1977; Schofield et al., 1997; Magalhaes et al., 1999].  Nevertheless, fine dust is somehow being injected into the atmosphere to support the observed haze and to supply local… and global… dust storms." 

     A pilot who is flying in zero visibility has to trust the instrumentation is the cockpit.  But the when the boundary layer – where sky meets ground, is clearly visible as it is in film from the Martian surface, and the instruments do not agree with what is being seen, it is time to question the accuracy of those instruments. The items in red in the paragraph above speak to the basic question asked throughout this web page (and developing technical paper).  In fact, if the atmospheric pressure of Mars is higher than advertised by NASA, the wind speeds found would be sufficient to get the job done.  Mars begins to make sense at the higher pressures.  It does not at near vacuum.   

THE EMPEROR HAS NO CLOTHES?  WHAT OTHERS SAY

     A major problem with everything asserted on this page, of course, is that I am just a 16-year old college freshman.  Who am I to assert that perhaps NASA has failed to draw the correct conclusions about the accuracy of their instrumentation, especially after so many probes to the Red Planet?  There has long been a controversy raging about whether or not Viking found life on Mars. Have I found justified reason to add to that controversy?

     A knee jerk response of some professors is that we could not have had so many successes on Mars if we did not understand the pressure there.  Perhaps, but there have been many failures, some unexplained, and only four landers that actually measured pressure. Look at the scoreboard.  Of the four landers that have measured pressure, three used one type of instrument (the Tavis), and the fourth used a 26-gram Vaisala Barocap ® device that was designed with a much too limited pressure range in mind (5 to 12 mbar) based exclusively on the Tavis device.   As such, our successes may have been despite of our misunderstanding of pressure there, and not because of our accurate data about it.  In fact, the first successful landers, (the two Vikings) were designed to land with no prior pressure data.  Meanwhile, to view responses and rebuttals to the issues raised on this page as they come in, please see Mars E-mails.