Mars Pathfinder Pressure Findings

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 Base on Mars? Seasonal Pressure Altitude Calculations Seismic Activity on Mars? Perserverance Weather Data MSL Years 5-6 Winter MSL Year 5 FALL MSL Year 5 Summer MSL Year 5 Spring MSL Years 4-5 Winter MSL Year 4 FALL MSL Year 4 Summer Weather MSL Year 4 Spring Weather MSL Yr 3-4 Winter Weather MSL Fall Yr 3 Weather MSL Yr. 3 Summer Weather MSL Yr. 3 Spring Weather Martian plume March 25 2017 MSL Ultraviolet 3 YEARS OF MSL UV Desai, EDL, Parachutes & ExoMars Mars winter vs. summer temps Helo to Mars 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 Report 4.1-4.1.2 Report 5 to 6 Report  7-7.2.1 Report 8 Report 9 Report 10 Report 11 Global Dust Storm Report 12 Report  13-13.2 Report 13.3-13.5 Report 13.6 Report 14-15 Report 15.1 Report 15.2-15.3 Report 15.4-15.6.2 Report - Report Report 16-16.1 Report 17-20 Report References Rebuttal of REMS Report Running water on Mars MSL Year 0 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 Updated Secrets of Mars 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 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 Missing data Mitchell Report Old Mars Report All MPF Temps ExoMars fails Did Spirit find past life? MSL ground temps go haywire OPACITY AT MSL Luminescence on Mars Dust Storms & Microorganisms 2018 Global Dust Storm Links to Sections of the Basic Report

Pathfinder Data is Best Compared to Viking 1 Data (Updated 9/22/2014)

NOTE added on September 22, 2016: A major article comparing MPF and MSL temperatures is found at


Mars Pathfinder landing Data:

Landing Date: July 4, 1997.         Date Operations Terminated: September 27, 1996

Martian Month: 5 (summer)         Martian Month terminated:7 (fall)

Ls at landing: 142.7                    Ls at termination: 188.4

Martian Sol at landing: 304.         Martian Sol at termination: 387

Altitude of MPF: -3.682 km.

Comparative altitudes of other landers with MET capability:

Viking 1: -3.627 km (most similar to Pathfinder). Based on scale height calculations, at a time when pressure at areoid is 6.1 mbar, pressure at Viking 1 would be expected to be about 8.5345 mbar and at Pathfinder it would be about 8.5781 mbar.

Viking 2: -4.505 km

Phoenix: -4.126 km

This page addresses Pathfinder pressure data published at:

The Mars Pathfinder Atmospheric Structure Investigation/Meteorology (ASI/MET) Experiment

Science 5 December 1997:
Vol. 278 no. 5344 pp. 1752-1758
DOI: 10.1126/science.278.5344.1752

The relevent pressure text and figures from the above article are include below. This author's comments are added in red.

Pressure data. During sols 1 through 30 (Roffman note: Martian sols 304 to 333; Ls 142.7 to 158) surface pressure at the landing site underwent substantial daily variations of 0.2 to 0.3 mbar, which were associated primarily with the large thermal tides in the thin martian atmosphere (11) (Fig.3A). Daily pressure cycles were characterized by a strong semidiurnal oscillation, with two minima and two maxima per sol, together with diurnal and higher-order components, although there was considerable day-to-day variability (Fig. 3B). The presence of a large semidiurnal tidal oscillation is indicative of atmospheric dustiness over broad regions of Mars and over an altitude range of at least 10 to 20 km (19).

UPDATE OF 11/19/2014: Schofield et al. (1997)1 indicate that while Pathfinder was operational from July 4 to September 27, 1997, it had no pressure data for the most crucial sol – its first operational day on Mars. The reason given by the above reference is there were “various spacecraft software reset and downlink problems.” If the problems only occurred after the first day; and if the first day’s pressure data was consistent with the Vikings, then Pathfinder’s data could be used to refute the claims made herein. However, that is not the case. We are still dealing with a Tavis transducer with no way to keep the dust out of its pressure tube on or in the seconds before landing, and no way to change a clogged dust filter. The critical time is in the final landing process. So when the spacecraft has to reset the software and correct downlink problems then, the issue of exactly what is entailed in these corrections becomes one of extreme importance.






Figure 3 A.  Time-averaged surface pressures measured by the MET instrument over the first 30 sols of the Pathfinder landed mission. The averages are primarily over the 3-min default measurement sessions, of which there are nominally 51 per sol; and the resulting points have been connected with straight lines, except for sols 12 through 15, where cubic spline interpolation has been used to fill data gaps of about 8 hours in length. MET operation was restricted to nighttime observations during this period to prevent spacecraft resets associated with MET data collection. The major gaps in the data set at sols 1, 8, 11, and 17 (Roffman note: Mars sols 304, 311, 314 and 320) are caused by various spacecraft software reset and downlink problems. After sol 17, the reset problems associated with MET were corrected, and continuous sampling was resumed. The long-term trend in pressure is represented by a third-order polynomial fit to the data (solid curve).
       Roffman note: During these days, pressures at Viking 1 varied from 6.51 mbar to 7.11 mbar between Ls 142.7 and Ls 154.017, however there is no Viking data posted for the period from then through Ls 158 so a full comparison is not possible. The pressure of 7.11 mbar is about 0.25 mbar higher than what was seen by the Pathfinder. See right columns on pages D-5 to D-27 of Annex D to our report for the corresponding Viking data. Again, because Viking 1 was about 55 meters higher than Pathfinder, the pressures that it saw should have been slightly lower than what was recorded by Pathfinder.
     Another major problem here is that beyond the data that is totally missing for Viking 1 from its sols 117 through 133 (Mars sols 325 through 341), for at least 112 basically hourly (59-minute) time bins which is equal to another 4+ Martian days, the pressure readings were stuck for at least 4 time-bins. About 81 of the time bins saw pressure changes in the range of or greater than the 0.088 mbar resolution amount limited by digitization (see page 17 of the Basic Report). This was a bit less than 16% of the recorded pressure changes. 
1 Schofield, J.T. et al., (1997). The Mars Pathfinder atmospheric structure investigation meteorology (ASI/MET experiment, Science, 278, 1752-1758

Figure 3B.  Diurnal pressure cycles for sols 9 (solid line) and 19 (dashed line), illustrating the observed day-to-day changes in the diurnal pressure cycle and allowing details of the daily pressure variation to be seen more clearly.

A long-term trend in daily mean pressure was also seen. A third-order polynomial fit to the data shows that mean pressure fell slowly at the beginning of the period and rose at the end, with a minimum just under 6.7 mbar near sol 20 (L s ∼ 153°) (Fig. 3A). This time corresponds to the annual deep minimum in the seasonal pressure cycle associated with CO2 condensation and sublimation in the polar regions of Mars and was seen previously by the Viking landers (11).

The ASI/MET pressure sensor detected a variety of pressure variations on relatively short time scales. These ranged from seconds to hours and had magnitudes of 1 to 50 μbar. The shorter time-scale variations (<10 to 15 min) appear to be correlated with wind and temperature fluctuations and tend to be largest during late morning and early afternoon, when the boundary layer is most turbulent. The most dramatic pressure features were minima of 10 to 50 μbar, usually less than a minute in duration, associated with vortices (dust devils) passing over the lander. A particularly good example was seen during the continuous sampling of sol 25.