Proof Viking Pressure Sensors Failed

EFFECTS OF THE DUST STIRRED UP.

      If transducer pressure access tubes were blocked by dust and/or sand, then all the transducers could feel behind the blockage would only the pressure on the partially air-filled transducer. The blockage would prevent the transducers from sensing the actual ambient pressure. Changes to the pressure exerted and measured internal to the blockage would be due to heating caused by internal operating electronic equipment and in particular it would be due to heating by Radioisotope Thermoelectric Generator (RTG) heaters on board. In an effort to confirm this, the first thing sought was a consistent temperature spike at a set time.  With an automated requirement to turn on the heat, pressure would grow at the time of heating of the trapped air. When the order came to turn off the heat, pressure would decline. It was expected that the pressure pattern would thus resemble the inverse of the temperature in the ambient air, as the heater could be expected to come on to heat the internal environment most when the outside was reaching its coldest time of day or season (winter).

       A pressure rise was seen for much of the Martian year (especially late summer to early winter) in the time-bin ("hour") between 0.26 and 0.3 each morning (the Martian equivalent of 6:24 AM to 7:23 AM). In the time-bin 0.3 and 0.34 sols in the next hour each morning (7:23 AM to 8:22 AM) the pressures grew little more, stopped, or began to fall. The Viking Project data is based on 25 time-bins (like hours) with about 59 minutes in each.  It was expected that this optimal heating time might shift by a time-bin as sunrise moved later or earlier into the year depending on the season. This was also seen. Sometimes the biggest pressure rise of the day was at the .22 to .026 time-bin, and at other times the biggest shift was later in the 0.3 to .34 time bin, or even the following one.  However, once the shift was seen, it tended to stay set for many weeks. Table 1A shows the average pressure for six studies encompassing Viking 1's sols 1 through 350 (summer to winter).  Table 1B shows the average pressure for four studies encompassing Viking 2's sols 156 through 290 (early fall to winter). Table 2 has links to the specific data and graphs for pressure changes in each study.

Pressure increases seen in the 0.26 to 0.30 sol time frame were generally many times greater than pressure drops associated with dust devils. This data, if accepted, means that all previous conclusions by NASA about pressure with respect to Martian weather are incorrect.  Problems with the Pathfinder and Phoenix sensors are discussed in my earlier paper (see Section 2.4, Issues Raised by the Finnish Meteorological Institute (FMI) in our Basic Report for Mars Correct: Critique of All NASA Mars Weather Data, with Emphasis on Pressure).

(1) Winter Temperatures and Pressures. First we must look at Figure 5C above,. It indicates Sol-averaged temperatures for Viking 2.  It shows a minimum (coldest) temperature average in the vicinity of 160 K. I looked through the data provided by Professor Tillman and found two such days, with the coldest being on Viking 2 Sol 310 when the temperature averaged 162.4828 K.  I also went through the 25 time bins on Viking 2 Sol 292 and found an average temperature then of 165.288 K.  The pressure was slightly higher on Sol 292.  In fact, it was the highest average for a day that I saw, but I did not check every single day around it yet.  The average pressure on Sol 292 was 10.1228 mbar (for Sol 310 it was 9.8432 mbar). While this article focuses on the Vikings, the MSL Curiosity registered an 11.49 mbar pressure on its Sol 370 that essentially pegged out to at the maximum value that it could reecord. This suggests that the actual pressure was much higher for part of that day. It may also reflect what might have happened when a dust clot on its Vaisala sensor was knocked out while the rover drove over rocks. 

(2) Summer Temperatures and Pressures.  The warmest day found seemed to be around Viking 2 Sol 640. Then the temperature averaged 221.0836 K. The pressure for that day averaged 8.046 mbar.  Another warm day checked (Sol 740) had an average temperature of 212.176 K.  That day had a lower pressure average - just 7.402 mbar. A third warm day was seen at Viking 2 Sol 71 when the temperature averaged 211.8768 K and the pressure was 7.4532 mbar.

(2a). Update of November 2, 2013 for MSL Temperatures. Until July 3, 2013 we knew that since the MSL landing on Mars on August 6, 2012, the MSL REMS Team and Ashima Research had put out clearly erroneous winds, sunrise and sunset times, pressure units, dates on their reports, months and claims about relative humidity that were not reflected on their reports. We (wrongly) assumed however that at least the temperature reports were reliable. That assumption was demolished on July 3, 2013 when they revised all temperatures back to the landing, wiping out scores of days where they had claimed high temperatures above freezing. Some of these revisions are visible on the following Table:

Mariner 69's 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. This information had a definite impact on the aerodynamic shape of the Mars entry vehicle being designed, since weight and diameter would influence the craft's braking ability. Langley engineers had determined that aerodynamic braking was the only practical method for slowing down a lander as large as Viking for a soft touchdown. The entry vehicle would have a diameter of 3.5 meters, an acceptable ballistic coefficient that would help ensure Viking's safe landing on Mars.

    It appears that by Mariner 69's, the article is referring to the Mariner 6 and 7 flyby spacecraft that had their closest approaches to Mars on July 31, 1969 and August 5, 1969.  But their NASA-advertised radio occultation pressures for Mars were only 3.8 to 7.0 mbar. The 20 mbar figure is almost 3 times higher. And what are we to make about the 80 mbar figure that is refuted with the 20 mbar estimate?  Mariner 4 had flow by Mars on July 14, 1965. Its estimate of pressure on Mars was pegged at 4.1 to 7 mbar.  The NASA source for these lower pressures is found at http://nssdc.gsfc.nasa.gov/planetary/mars/mariner.html. See the results section under each Mariner mission. However, if NASA had the 20 mbar figure, and was publishing it too, again, the question must be asked, why in the world would it select pressure transducers for the Vikings that could only measure up to 18 mbar? As can be seen with Figure 7 below, there were pressure estimates of 20 mbar in 1965 (Evans), but after the Mariner 6 and 7 the issue was supposed to be settled with a maximum pressure at 7 mbar.  Why was a detailed NASA document written in 1978 still putting  forward the 20 mbar figure?  Perhaps someone realized what is abundandly apparent on my study. The Viking pressure data is fatally flawed.  Further, without a fix for dust ingestion by Pathfinder and Phoenix, they were also fatally flawed.  We must plan on the pressures seen by studies in 1965 or earlier. The MSL flew with the same mistakes made again. Based on the facts that that its pressure pegged out at maximum value on is sol 370, and the fact that the REMS Team actually originally reported pressures between 742 and 747 mbar (hPa) between September 1 and September 5, 2013 before revising them dwon by a factor of 100, there is reason to doubt all MSL pressure credibility. More, based on cumulostatus clouds seen 16 km above Pathfinder (13 km above areoid) it is actually possible to estimate a pressure at areoid of 510 mbar. See the data here.

       Pressure spikes for Viking 1 range up to an increase of as large as 0.62 mbar during sol fragment 0.26 to 0.30 (see data for Viking 1 Sol 332.3 at Ls 286.576) . An increase of 0.62 mbar in 59 minutes is equal to an increase in pressure that is over 10% of the 6.1 mbar pressure generally accepted as the average pressure at areoid on Mars!  
       The average daily pressure increase from Sol 200 to 350  sol was about 0.2154 mbar. It was taken from four time periods corresponding to early fall (20 sols during Ls 201.859 to Ls 213.736), fall (85 sols during Ls 214.316 to 268.687),  late fall to early winter (30 days during Ls 269.292 to Ls 287.862) and 16 days of winter during Ls 288.441 to 297.84. During these periods for 151 sols consecutive sols there was one day single pressure drop (Sol 240.3) and no steady pressure during in the 0.26 to 0.30 time-bins. Pressure increased 148 times  However, the 0.30 to 0.34 time-bins showed 36 occurrences where pressure did not change at all from the 0.26 to 0.30 time-bin, and there were 28 pressure drops in this time-bin. There were 87 pressure increases in the 0.30 to 0.34 time-bin. The 0.30 to 0.34 time-bin showed variation that should be expected with a weather pattern that naturally varies. The fact that there were almost no such variation in the 0.26 to 0.30 time -bin is evidence that the pressure transducers were being affected only by events ordered by an internal clock mechanism. The graphs on Figure 3 represent a little over 20% of the 669-sol Martian year.

DATA FOR THE SUMMER TO FALL PERIOD. Viking 1 Sols 150 to 199 were during the late summer to early fall (Ls 172.312 TO 201.294).  Click HERE for the data for these 50 days. During this interval the pressure rose in all 50 Martian days, but it again rose by more in the 0.26 to 0.3 time-bin (average rise 0.1332 mbar) than in the 0.3 to 0.34 time-bin (average increase just 0.0508 mbar).

       The pattern of increased pressure is much stronger late in the summer as is apparent in chart showing pressures for Viking 1 between its sols 1 to 116 and 134 and 199 (data sols 116 to 133 is not yet available on Professor Tillman's site).  The first chart starts at Ls 97.343 (the first day of summer is Ls 90) and goes through Ls 153.675, then the next chart resumes at Ls 163.359 and through and past the first day of fall (Ls 180) finishing at Ls  201.294. In the segment that runs from Ls 97.343 through Ls 153.675 (all summer) the average pressure increase in the 0.26 to 0.3 sol time-bin was only 0.023276 mbar).  It was less in the 0.3 to 0.34 time-bin (0.010431 mbar). The difference here is not significant, however, in the same time-bins for Ls 163.359 through Ls 201.294, we see an increase of 0.1224 mbar in the 0.26 to 0.3 sol slot, and only 0.0459 mbar in the 0.3 to 0.34 time-bin. The earlier "hour" has a pressure increase 2.67 times greater than the later time-bin.

       In looking over the temperatures outside of Viking 1 during the periods covered in the last paragraph, I was struck by how little temperatures changed in the 0.22 to 0.26 time-bin, in the hour before the time that I primarily focused on (0.26 to 0.34) each sol. For example, between sols 1 to 116, on 75 out of 116 Martian days, the outside temperature was between -84.01 ^º and -85.99 ^º C. These 75 days between Ls 97.343 through Ls 153.675 equate to about 64.65% of the days in question. During these days, by the 0.34 time bin, temperatures rose to as much as -39.22^º (on Viking 1 Sol 114.34 at Ls 152.611). The average temperature at the 0.34 sol time-bin was -53.265^º C (see Morning Temperatures on Mars). Note, the summer solstice at Ls 90 is not the day where the sun is highest in the sky at Local Apparent Noon for Viking 1. This is because Viking 1 landed in the "tropics" of Mars at latitude 22.48 ^º degrees North.  The vertical rays of the sun at solstice are at latitude 25.19^º degrees North. As such, the vertical rays at the Viking site are experienced before and after solstice.