# Debunked: Atmospheric pressure on Mars is 9 PSI, not 0.09 PSI as claimed by NASA

#### nathanmariels

##### New Member
I have working with a few hundred different pressure sensors of many types. High vacuum filament ones, high pressure ones on hydrogen reactors, ones used to measures the load suspended by cranes indirectly by geometry and hydraulic pressure, Barocaps, weather balloons, altimeters for custom drones, etc...

The Barocaps are extremely small and light. They were originally designed for one time use in weather balloons. They work well for that purpose, but accuracy, especially with temperature fluctuations, can be difficult to obtain. They output the pressure signal as a 14-12pF capacitance value, with only 2pF difference between min and max values. This makes noise, and even physical proximity to other things, affect the readings a fair amount, and without a calibration reference, hard to keep from drifting over time.

#### Amber Robot

##### Active Member
That is a really good question. There are absorption lines for O2, CO2, N2, Ar, and H20, but the ratios are all based on atmospheric pressure. If the pressure is not as expected, its rather difficult to figure out from the available data. The index of refraction and diffusion seem to imply N2, H20 and O2, but with lower O2 and H20 than Earth. Even if the atmospheric pressure is 9 PSI at the surface, I don't know that humans would want to breath it, but it would definitely make surviving there much easier in any case.

Without any specific data for the ratios, my guess would be 13% O2, 1% CO2, 1% AR, 85% N2, but I don't have enough information to have confidence in these numbers.

I had thought the atmospheric pressure of Mars to be around 10 PSI for years until I found the math/software errors that all pointed to 9 PSI.

(This is why my page of notes changed from mars10psi.com to mars9psi.com a few years ago.)
So, despite decades of spectroscopic study of the Martian atmosphere from the ultraviolet airglow to the infrared absorption’s, it has eluded planetary scientists that there’s an order of magnitude more oxygen in the Martian atmosphere than CO2?

Having both read and contributed to the literature on this subject, I will err on the side of remaining unconvinced by your assertion, especially since you preface it with an admission of a lack of specific data.

#### Easy Muffin

##### Member
There's archived data from a number of landers at https://pds-atmospheres.nmsu.edu/data_and_services/atmospheres_data/MARS/mars_lander.html

I've not got a whole lot of time right now so I only had a look at the Viking sets but they too appear to show the same pressure variations.

These are the raw daily mean pressures in millibars. Viking 1 recorded a lowest value of 6.769 mbar and a highest of 9.055 mbar; Viking 2 measured a low of 7.357 mbar and a high of 10.198 mbar. The same 25-ish % variance. I'm not sure how sensor drift could account for the seasonal decrease and subsequent increase in pressure levels. I didn't check other data sets but I would assume they are quite similar.

#### nathanmariels

##### New Member
In regards to the Viking data:

"C Pressure mb = millibars, 1 mb = 100 hPa, where
C hPa = hecta Pascals"
-Viking Lander 1 Binned and Splined data Rev 2.2 97/6/19, JET, lines 50-51
https://www-k12.atmos.washington.edu/k12/mars/data/vl1/segment2.html

The conversion factor above is incorrect.
A correct conversion factor is: 1 mb = 100 Pa
A correct conversion factor is: 100 mb = 100 hPa

(mb: millibars, hPa: hectopascals, Pa: pascals, 100 Pa = 1 hPa)

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#### nathanmariels

##### New Member
I am not claiming to understand the martian atmospheric composition or pressure fluctuations better than anyone else.

I am stating that I think the average martian atmospheric pressure is off by a factor of 100.

#### Easy Muffin

##### Member
Where I think your argument runs into a problem is that when you say that the average pressure is off by a factor of 100, then the pressure variations must be off by that same factor, since these are the very readings that make up that average. So the big question on my mind then is, what mechanism could possibly cause regular pressure variations of 13 kPa? That's quite the dramatic change, and whilst the seasonal shrinking and growing of the ice caps can explain the mainstream difference of 130 Pa quite well, I don't think it could adequately explain a difference 100 times greater.

#### nathanmariels

##### New Member
Where I think your argument runs into a problem is that when you say that the average pressure is off by a factor of 100, then the pressure variations must be off by that same factor, since these are the very readings that make up that average. So the big question on my mind then is, what mechanism could possibly cause regular pressure variations of 13 kPa? That's quite the dramatic change, and whilst the seasonal shrinking and growing of the ice caps can explain the mainstream difference of 130 Pa quite well, I don't think it could adequately explain a difference 100 times greater.
If the CO2 ice caps explain a 15% pressure change at 700 Pa, I don't see why they don't explain a 15% pressure change at 70,000 Pa

#### Easy Muffin

##### Member
It's the sheer amount of CO2 that would have to regularly transfer between ice cap and atmosphere to create a pressure difference that much higher. We're talking about a 1/4 of the atmosphere, so if it really is 100 times denser, how does all that extra mass get into the atmosphere, and how does it leave it again?

#### Hevach

##### Senior Member.
At sea level, 14.7 PSI, the MR-80B engines have > 80% of vacuum thrust. These engines can run with a combustion chamber pressure from 2 PSI to 282 PSI, 1:100 ratio.

The lander has 8 of these engines, for 6400 lbs total thrust, lifting an effective lander weight of < 1000 lbs (30% earth gravity).

MR-80B engines can handle 460 PSI maximum back pressure and were extensively tested at 14.7 PSI as well as 0.25 PSI.

I don't see any issues here with the rocket engine working at 9 PSI.

I do, however, find many issues related to excessive forces during parachute decent and aerobraking, when assuming 0.09 PSI, that match models nicely at 9 PSI.
All those numbers you gave are edges, it can't throttle to minimum under 1 atmosphere of backpressure.

But back to the question: It used four engines to hover*, at that thrust level the nozzle output pressure of 1.8 psi - and since you keep going back to the fact that it had 8, if it used all 8 then the nozzle pressure would be 0.9 psi, so same question: Take as read that it could operate at this low thrust level in 9 psi, then why at that thrust level does it have an expanding exhaust plume if ambient pressure is 9 psi?

#### nathanmariels

##### New Member
All those numbers you gave are edges, it can't throttle to minimum under 1 atmosphere of backpressure.

But back to the question: It used four engines to hover*, at that thrust level the nozzle output pressure of 1.8 psi - and since you keep going back to the fact that it had 8, if it used all 8 then the nozzle pressure would be 0.9 psi, so same question: Take as read that it could operate at this low thrust level in 9 psi, then why at that thrust level does it have an expanding exhaust plume if ambient pressure is 9 psi?

I know that at some points of the decent, MSL did use only four of the eight, as the rockets became less efficient at low thrust levels.

Do you have any images showing expanding exhaust plumes from the decent?

#### nathanmariels

##### New Member

This is one of the few images from the decent of Perseverance that I can find that show anything about shape of the exhaust plumes. From how they are effecting the ground, they look rather narrow to me.

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#### nathanmariels

##### New Member

And in this reflection, where is appears very narrow.

All of the times that the rocket nozzles are in view of a camera, there is no apparent plume. I think this is because they were at such a low thrust level that no flame was coming out of the bell housing. This would not be the case near vacuum.

This last one, which I cropped, changed the brightness, and changed the contrast on, you can see the dull orange glow of the combustion chamber, but no plume outside the bell housing.

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#### nathanmariels

##### New Member
So, despite decades of spectroscopic study of the Martian atmosphere from the ultraviolet airglow to the infrared absorption’s, it has eluded planetary scientists that there’s an order of magnitude more oxygen in the Martian atmosphere than CO2?

Having both read and contributed to the literature on this subject, I will err on the side of remaining unconvinced by your assertion, especially since you preface it with an admission of a lack of specific data.
"The principal difficulty affecting all of the photometric and polarimetric investigations is that of distinguishing between the amount of light scattered by the Martian surface, by the solid particles in the atmosphere and the atmosphere itself. The surface pressure can be computed also from the pressure broadening of the lines in the Martian band spectrum of CO2. The first results of the spectroscopic method disagree by an order of magnitude from previously accepted values, which were based on photometry and polarimetry. Other spectroscopic measurements made by numerous investigators in 1964 and 1965 confirmed this disagreement mentioned above."
-Karl D Rakos, The Atmospheric Pressure at the Surface of Mars, Lowell Observatory Bulletin No. 131, 1965

There are multiple ways of calculating the atmospheric pressure, all of which depend on two data points. Earth and Mars. When Viking returned a pressure reading indicating 0.09 PSI, the methods that worked at 14.7 PSI on Earth and at 0.09 PSI on Mars were considered valid. All of these methods are dependent on the assumed pressure being correct in the first place. If you assume 9 PSI, a whole different set appear correct, including a really simple one relating gravity and atmospheric pressure I came up with (see my page of notes at mars9psi.com).

There is an error in the Viking log pressure data of. The incorrect conversion factor is used, and it is in the log files.

There is a units error on MSL and Perseverance of the same 1 to 100 difference. The pressure sensor range is 1-1150 hPa, and NASA states it as 1-1150 Pa. (100 Pa = 1 hPa.)

The backshell pressure sensor on Perseverance only went to 4.2PSI max, but read the maximum value of 4.2PSI. They are assuming this sensor failed.

The diffuse light can not be explained by dust, and there is no visible dust setting on anything or detectable my any means, nor does it affect visibility.

The exhaust plumes from the decent engines on Perseverance do not show expanding plumes as they would at 0.09 PSI.

#### nathanmariels

##### New Member
Mars helicopter just flew.

No dust clouds when hovering. Doesn't seem like Mars gets it's diffuse light from the dust.

Anyone able to get the telemetry data from it? Rotor RPM vs. motor current would be a very good indicator of atmospheric pressure.

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#### Amber Robot

##### Active Member
"The principal difficulty affecting all of the photometric and polarimetric investigations is that of distinguishing between the amount of light scattered by the Martian surface, by the solid particles in the atmosphere and the atmosphere itself. The surface pressure can be computed also from the pressure broadening of the lines in the Martian band spectrum of CO2. The first results of the spectroscopic method disagree by an order of magnitude from previously accepted values, which were based on photometry and polarimetry. Other spectroscopic measurements made by numerous investigators in 1964 and 1965 confirmed this disagreement mentioned above."
-Karl D Rakos, The Atmospheric Pressure at the Surface of Mars, Lowell Observatory Bulletin No. 131, 1965
That’s a single reference from over 50 years ago. A lot more research on the atmosphere of Mars using spectroscopy has been done by now. Irrespective of the pressure, if there were 100 times more oxygen on the planet it would have been noticed and there have been spacecraft studying the Martian atmosphere in the intervening five decades! Including, for example:

Herschel/HIFI observations of Mars: First detection of O2 at submillimetre wavelengths and upper limits on HCl and H2O2

P. Hartogh, et al. (A&A 521, L49 (2010))

#### nathanmariels

##### New Member
That’s a single reference from over 50 years ago. A lot more research on the atmosphere of Mars using spectroscopy has been done by now. Irrespective of the pressure, if there were 100 times more oxygen on the planet it would have been noticed and there have been spacecraft studying the Martian atmosphere in the intervening five decades! Including, for example:

Herschel/HIFI observations of Mars: First detection of O2 at submillimetre wavelengths and upper limits on HCl and H2O2

P. Hartogh, et al. (A&A 521, L49 (2010))
I don't know if there is more oxygen or not. I'm just stating that the pressure is 100 times what is assumed and that concentrations of any particular gas can not be used alone to know the atmospheric surface pressure.

For Viking and MSL, the raw telemetry data gives values that translate to pressures of 8.5 PSI and 9 PSI.

The Viking log files that list 7mb also incorrectly state the equation used to make those numbers. The log files state that 1mb=100hPa, where the correct formula is 100mb=100hPa.

"C Pressure mb = millibars, 1 mb = 100 hPa, where
C hPa = hecta Pascals"
-Viking Lander 1 Binned and Splined data Rev 2.2 97/6/19, JET, lines 50-51

REMS Instrument Pressure Sensor (Vaisala Barocap):
"Pressure in the range of 1 to 1150 Pa with a resolution of 0.5 Pa"
- NASA website

"Pressure range 50 ... 1150 hPa"
"Resolution 0.5 hPa"
- Vaisala Barocap Datasheet

REMS testing of Barocap: Capacitance varies from 14 to 12 pF over the range of 0-1000 Pa
- REMS Space Science Reviews 2012 DOI 10.1007/s11214-012-9921-1, figure 12

My testing of Barocap: Capacitance varies from 14 to 12 pF over the range of 0-1000 hPa

100 Pa = 1 hPa

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#### Amber Robot

##### Active Member
I don't know if there is more oxygen or not. I'm just stating that the pressure is 100 times what is assumed and that concentrations of any particular gas can not be used alone to know the atmospheric surface pressure.
When I asked you what the other 99% of the atmosphere was, since you seemed to agree with the measured partial pressure of CO2, you presented a number for oxygen that is 100 times larger than has been observed spectroscopically. If you want to walk back that number, then fine, but you still need to account for what the other 99% of the atmosphere is and what the spectral signatures of that would be.

I’m not going to discuss pressure sensors with you because I’m unfamiliar with the material, but I have experience in spectroscopy of planetary atmospheres. I also know you can’t just pick one measurement that appears to be wrong and come to a conclusion that would have significant consequences on other observables. Consequences that aren’t seen.

If you have citations of spectroscopic observations of the Martian atmosphere that support an atmosphere a hundred times thicker than what is currently believed I would be happy to read them.

#### nathanmariels

##### New Member
When I asked you what the other 99% of the atmosphere was, since you seemed to agree with the measured partial pressure of CO2, you presented a number for oxygen that is 100 times larger than has been observed spectroscopically. If you want to walk back that number, then fine, but you still need to account for what the other 99% of the atmosphere is and what the spectral signatures of that would be.

I’m not going to discuss pressure sensors with you because I’m unfamiliar with the material, but I have experience in spectroscopy of planetary atmospheres. I also know you can’t just pick one measurement that appears to be wrong and come to a conclusion that would have significant consequences on other observables. Consequences that aren’t seen.

If you have citations of spectroscopic observations of the Martian atmosphere that support an atmosphere a hundred times thicker than what is currently believed I would be happy to read them.
I would be so nice if the next rover had a mechanical pressure gauge and a prism in view of a camera.

#### Amber Robot

##### Active Member
I would be so nice if the next rover had a mechanical pressure gauge and a prism in view of a camera.
Scientists have been performing atmospheric spectroscopy of Mars for about 60 years using ground- and space-based instruments, including Mars orbiters. I don’t think we need to wait for a “prism in view of a camera” to ascertain the Martian atmosphere.

#### Hevach

##### Senior Member.
All of the times that the rocket nozzles are in view of a camera, there is no apparent plume. I think this is because they were at such a low thrust level that no flame was coming out of the bell housing. This would not be the case near vacuum.
All rocket exhausts are less visible in lower pressure, not more (this is particularly visible in a launch video for any long-burn stage like the Falcon Heavy core or STS main engines, the plume becomes larger and more transparent the higher the altitude, and from Falcon second stage videos you can see that in near vacuum the plume becomes effectively invisible, even for a karalox engine that produces a brilliant flame plume normally).

These in particular are hydrazine monopropellant rockets, which produce almost no visible flame plume, especially in near vacuum. They should be visible in 9 psi, but not very well and the engineering cameras are not particularly high contrast. The only way to tell they are expanding plumes is from the stable shock front where the cones overlap.

You might be confusing them with hypergolic hydrazine bipropellant rockets like the Superdraco, which produce a dull reddish brown exhaust and visible flame plume.

#### nathanmariels

##### New Member
Scientists have been performing atmospheric spectroscopy of Mars for about 60 years using ground- and space-based instruments, including Mars orbiters. I don’t think we need to wait for a “prism in view of a camera” to ascertain the Martian atmosphere.

Then can you tell me the pressure range of the pressure sensor used on MSL and Perseverance?

Is it 1150 Pa or 1150 hPa?

It's reading 60% of one of those two values.

Personally, I agree with the data sheet and the ESA, and think it's 1150 hPa. That would make the surface pressure around 9 PSI.

NASA is assuming it's 1150 Pa. To compensate for discrepancies, they just use a different Gas Constant on mars in simulations for the mars helicopter. (Really nice to see the helicopter fly.)

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#### Amber Robot

##### Active Member
Then can you tell me the pressure range of the pressure sensor used on MSL and Perseverance?

Is it 1150 Pa or 1150 hPa?

It's reading 60% of one of those two values.

Personally, I agree with the data sheet and the ESA, and think it's 1150 hPa. That would make the surface pressure around 9 PSI.

NASA is assuming it's 1150 Pa. To compensate for discrepancies, they just use a different Gas Constant on mars in simulations for the mars helicopter. (Really nice to see the helicopter fly.)
I already said I have no better information than you about pressure sensors. I could google it as easily as you can.
ETA: ok, here’s a link with some detailed information on the pressure sensors used:

There’s a lot of information so I’m not cutting and pasting it all in. But it includes lots of technical specs and calibration results.

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#### Amber Robot

##### Active Member
Also, here’s a paper showing results off in situ atmospheric composition measurements showing 95% CO2.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE006175

So, if the pressure is 100 times higher than scientists claim then CO2 density is also 100 times higher and that would seem to be ruled out by six decades of spectroscopy.

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#### Mendel

##### Senior Member.
I already said I have no better information than you about pressure sensors. I could google it as easily as you can.
ETA: ok, here’s a link with some detailed information on the pressure sensors used:

There’s a lot of information so I’m not cutting and pasting it all in. But it includes lots of technical specs and calibration results.
You've been here long enough, you ought to know you absolutely need to copy and paste your sources because of metabunk's link policy.

Article:

### PS Science Objectives and Requirements​

The MEDA Pressure Sensor (PS) will continue a long history of pressure measurements from the surface of Mars that began with the Viking landers and continue through the currently operating Mars Science Laboratory/Curiosity rover and the InSight lander (Harri et al. 2014a; Haberle et al. 2014; Banfield et al. 2020). Surface pressure measurements are important for understanding the global dynamics, mass balance, CO2 and dust cycles, etc. among other interesting phenomena of the Martian atmosphere, which in turn enables a better understanding of the current Martian climate and a higher probability of being able to successfully model a past Martian climatic state.

The current Martian atmosphere is 95.1% CO2 (Trainer et al. 2019), of which ∼30% condenses out in polar caps annually. Surface pressure sensors are well-suited to tracking this process, and by comparing MEDA measurements to those over the past 45 years, it may be possible to discern any differences in this annual global cycle (Haberle and Kahre 2010).

[..]

### PS Design Description​

MEDA PS is a miniature pressure device based on Finnish company Vaisala, Inc. Barocap® sensor head and transducer electronics. The transducer measurements are controlled by Vaisala proprietary ASIC. The technology of the Barocap® is well known and it has previously flown in 6 missions, including MSL (REMS-P) and ExoMars 2016/Schiaparelli lander (DREAMS-P). MEDA PS design is very similar to REMS-P (Harri et al. 2014a), inheriting some parts also from DREAMS-P (Esposito et al. 2018).

Barocap® is a micro-machined capacitive pressure sensor head. Pressure moves the capacitor plates in the sensor, changing its capacitance, as shown in Fig. 6. This movement is not sensitive to the composition of the gas medium, resulting in the same capacitance change in terrestrial air or for the Mars CO2 atmosphere.

The capacitance of the sensor head is not only pressure, but also temperature dependent, and so accurate reference temperature measurement is needed to correctly interpret the output capacitance of the sensor head. The nominal capacitance of NGM and RSP2M type Barocap® sensor heads used in MEDA PS is around 27 pF and 14 pF, respectively. These sensor head types have been specifically modified and manufactured by Vaisala, Inc. for FMI for Mars applications.

[..]

NGM Barocap® is a new sensor head type for Martian applications by Vaisala with the best resolution so far and very good stability. Because of its size and structure it has bigger temperature dependence than RSP2M, which makes it more susceptible to temperature changes and can result in longer warm-up time after power on. The heating effect can, however, be compensated by data processing. The RSP2M, the sensor head used also in REMS-P sensor onboard MSL, has slightly worse resolution than NGM, and worse stability, but it’s warm-up time is less than 2 s. Unlike NGM, which is shorted in pressures above ∼50–75 hPa, RSP2M can also be measured in ambient Earth conditions.

[..]

### PS Calibration​

#### Overview​

The first stage of the pressure and housekeeping temperature calibration of the PS was performed in FMI calibration laboratory using the setup shown in Fig. 8 and Fig. 9. The pressure calibration was done against transfer references, which in turn were calibrated against a national standard reference sensor. The total accuracy of the reference pressure sensor (Baratron 10 Torr) was 1 Pa, and the time constant was 400 ms in the nominal position and 25 ms in the fast position (MKS Instruments 1997). The reference temperature accuracy was 0.25 ∘C.

[..]

Thermal vacuum environment is created by placing the pressure vessel inside the temperature test station. Temperature inside the vessel can then be controlled within the operational range of the temperature test station. Temperature inside the pressure vessel is measured with two dedicated Pt100 temperature sensors. High vacuum is achieved with a combination of a rotary vane vacuum pump and a turbomolecular pump. In the Martian pressure range the pressure inside the pressure vessel is controlled with a commercial PACE pressure control unit.

Article:
[TD]
MEPAG Goals (2014)InvestigationRequirementsPerformance
Goal II, Obj. A1, A4
Goal III, Obj. A3
Goal IV, Obj. B4, B7.
Detection of dust devil pressure signatures.The PS resolution shall be better than 0.5 Pa.NGM resolution in nominal mode (1 Hz measurement) ∼0.12 Pa. RSP2M resolution in nominal mode in order of 0.3-0.4 Pa.
The sensor shall be able to detect pressure changes with a variation speed of at least 1 Pa/s (PS’ response time shall be equal or better than [1 sec]).On sensor level <1 Pa/s. On rover level achieved by heritage in the design (similar to REMS onboard MSL).
Goal II, Obj. A1, A4
Goal III, Obj. A3
Goal IV, Obj. B1, B7.
Seasonal and diurnal pressure cyclesThe PS shall have a range of [1-1200 Pa] [Req. L4-MEDA-05]. Note: the calibration shall be optimized for Mars range 400-1200 Pa and also for high vacuum.The sensor has been calibrated in the range of [0–1400 Pa].
Goal II, Obj. A1.Pressure oscillations on the diurnal and hour scaleThe PS accuracy shall be equal or better than [+/-20 Pa] from [1 to 400 Pa] and [+/-10 Pa] from [400 to 1200 Pa], over the operational temperature range of [-45 C to +55 C] [Req. L4-MEDA-43].With preliminary calibration coefficients, the accuracy of measurements performed during rover level tests is better than +/-5 Pa. Final calibration coefficients and accuracy BOL will be determined after the cruise calibration checkout.

What do we learn from this?

1) There are different models of barocaps, and the datasheet for one model doesn't apply to another model.

2) They used a vacuum chamber to calibrate the sensor. (There's a picture of it in the source.) I think they'd have noticed if the pressure was off by a factor of 1000.

#### Mendel

##### Senior Member.
Also, here’s a paper showing results off in situ atmospheric composition measurements showing 95% CO2.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JE006175

So, if the pressure is 100 times higher than scientists claim then CO2 density is also 100 times higher and that would seem to be ruled out by six decades of spectroscopy.
I don't see any reference to "six decades of spectroscopy" in that paper.

But it does support the idea that the CO2 ice caps should be larger than they are if such a significant portion of it freezes each year, and its density is comparable to Earth; I am thinking how much water we have in the air, and how much ice and snow we get here on Earth.

#### Amber Robot

##### Active Member
I don't see any reference to "six decades of spectroscopy" in that paper.

But it does support the idea that the CO2 ice caps should be larger than they are if such a significant portion of it freezes each year, and its density is comparable to Earth; I am thinking how much water we have in the air, and how much ice and snow we get here on Earth.
This paper isn’t about spectroscopy, yes. As I said it was in situ measurement of composition that demonstrates the Martian atmosphere is predominantly carbon dioxide.

Since Nathan seemed to agree that the CO2 columns measured by remote sensing were accurate (maybe he didn’t really) then the pressure can’t be off by two orders of magnitude. My remark about six decades of spectroscopy is that Nathan is focusing on a single datum to bolster his opinion about the pressure whereas there has been considerable science performed independently of that datum that would be hopelessly wrong all these years and I find that extremely unlikely given my understanding of how molecular spectroscopy is performed.

I apologize for not cutting and pasting the information in. I just wasn’t sure what part of the voluminous detail would be something Nathan would find compelling (if any). But I will be sure to do better in the future.

#### Mendel

##### Senior Member.
I apologize for not cutting and pasting the information in. I just wasn’t sure what part of the voluminous detail would be something Nathan would find compelling (if any). But I will be sure to do better in the future.
No need to apologize.
But you're not doing it for him; you're doing it for me and everyone else who reads your posts, including anyone who reads this in five years when some of the links may have changed. I tend to pick what I found compelling when doing excerpts.

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#### Amber Robot

##### Active Member
And what would account for the color of the sky if not dust (regardless of the atmospheric pressure)? And what would account for what look like the occasional global dust storm that can be seen from Earth?

By the way, that “ghost” image is a strange artifact. Why would that happen?

#### Mick West

Staff member
By the way, that “ghost” image is a strange artifact. Why would that happen?
I suspect the effect is highlighting the change from the average for each pixel - i.e. it subtracts the average frame (or maybe even just the first frame) from the current frame, which will give a very slight image of the dust. This is then ramped up to 100% of the dynamic range, and then overlaid on the current frame.

Since Ingenuity is there a lot, it contributes a lot to the average for those pixels, and so you get a ghost.

#### Amber Robot

##### Active Member
I suspect the effect is highlighting the change from the average for each pixel - i.e. it subtracts the average frame (or maybe even just the first frame) from the current frame, which will give a very slight image of the dust. This is then ramped up to 100% of the dynamic range, and then overlaid on the current frame.

Since Ingenuity is there a lot, it contributes a lot to the average for those pixels, and so you get a ghost.
Ok. I can see that for the video on the left, but it seems like the video on the right is the original video. Is that incorrect? Are they both enhanced? My original thought was that the video on the right was there for context.

#### Mick West

Staff member
Ok. I can see that for the video on the left, but it seems like the video on the right is the original video. Is that incorrect? Are they both enhanced? My original thought was that the video on the right was there for context.
They are both enhanced. The one of the left is the pixel differences, the one of the right it that overlaid on top of the original.

#### Mick West

Staff member
A rough recreation of the dust detection. Layer 2 is the average of the first 100 frames and is set to subtract. Both layers have a 1.5 pixel gaussian blur. Then there's an overall "Levels" adjustment layer to boost the faint image.

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#### Hevach

##### Senior Member.
Now that Ingenuity has flown, there's some other facts:

4:10:
"What would happen if you just took your Mars helicopter and tried to take off on Earth?"
"It would just make a lot of noise and it probably wouldn't get to full head speed... It's like trying to swim in a thick soup."

There was an assumption up the thread that it would fly better, which would show in lower RPM and power draw in the motor. Which is reasonable, since the same pressure/2 factor shows up in the helicopter lift equation as the parachute equation I posted on page 1, so all things being equal you'd get 50x more lift. I honestly didn't even think to challenge that particular assuption.

However, not all things are equal: The rotors are large and have a steeper angle than is normal for similar devices on Earth. They spin at 2400 RPM, which is a little high for that type of rotor but not by a lot - most of the lift comes from the size and angle, not raw speed. However, the motor is small and can't handle resistance. This thing was made to fly in expected Martian conditions, 9psi also come with 50x more resistance against rotation.

This leaves out some bits - we'd need a lot more data to figure out where the 'break even' point is where added lift of having more air to push is cancelled out by the air resistance, so I can't say for *sure* that 60% earth sea level is on the wrong side of that point, but this thing was designed with mass as the main factor and with temperature control already occupying much of that (and a symbolic payload as dead weight).

#### Amber Robot

##### Active Member
They are both enhanced. The one of the left is the pixel differences, the one of the right it that overlaid on top of the original.
Thanks for clarifying that for me.

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Debunked: Construction worker Philip Morelli experienced an explosion in the sub-basement of the North Tower 9/11 0
Debunked: ABC News correspondent George Stephanopoulos reported an explosion in the subway 9/11 1
Debunked: Debris from twin towers was projected upward by explosives 9/11 13
Debunked: Government officials revealed having foreknowledge of Building 7’s collapse 9/11 58
Debunked: NIST computer simulation of Building 7 collapse is inaccurate 9/11 22
Debunked: FEMA reported finding evidence that steel had melted. 9/11 47
Debunked: VP Dick Cheney ordered a standdown of jet fighters on 9/11 9/11 16
Debunked: Claim that Bobby McIlvaine's injuries ("lacerations") are best explained as result of glass shards and debris from bombs 9/11 21
Debunked: World Trade Center should not have collapsed due to 9/11 fires 9/11 3
Debunked: Firefighter reports of secondary explosions 9/11 3
Debunked: Steel was hurled hundreds of feet by explosives 9/11 4
Debunked: Demolition Explosion Before Collapse of South Tower 9/11 2
Debunked: Explosion in South Tower Lobby 9/11 5
Debunked: Mysterious Explosion Before the Flight 11 Crash 9/11 32
Debunked: Marx: "The classes and the races too weak to master the new conditions must give way... They must perish in the revolutionary Holocaust" Quotes Debunked 0
Poll : Which DOD Navy video do you consider debunked ? UFO Videos and Reports from the US Navy 41
Debunked: Diving Triangle UFO Photos from Reddit [Fake] UFOs and Aliens 37
[Debunked] Object Seen From Airplane Above Canberra: 04 Apr 2012 Skydentify - What is that Thing in the Sky? 5
Debunked: Claim that Joe Biden's hand passes through microphone during White House press gaggle, 16th March 2021 Election 2020 8
Debunked: "Interdimensional being" caught on CCTV in Neza, Mexico Ghosts, Monsters, and the Paranormal 6
Debunked: missing cable on Perseverance landing footage proves it is fake. General Discussion 3
Debunked: Biden's Oval Office "Coming Apart at the Seams" [It's a Door] Election 2020 19
Debunked: UFO over California Highway (TMZ) UFOs and Aliens 1
Debunked: 7 Alleged photos of aliens UFOs and Aliens 9
Debunked: Biden signing "Blank" Executive Orders Election 2020 5
Debunked: Biden in "Fake" Oval Office Election 2020 27
Debunked: UN hidden camera: the first UFO contact happened [Deep Fake] UFOs and Aliens 3
Debunked: 94% of Fulton County Ballots Manually Adjudicated [It's a Process all Batches go Through] Election 2020 0
Debunked: "Missile Strike" caused Nashville Explosion General Discussion 3
Debunked: Nashville Explosion was "Across the Street" from the RV General Discussion 0
Debunked: "Error rate of 68.5% Allowable is .0008%" [Neither is True] Election 2020 4
Debunked: Claim that the Electoral College Count On Jan 6 will Change the Election Election 2020 136
Debunked: Einstein wrote "blind belief in authority is the greatest enemy of truth" Quotes Debunked 12
Debunked: Navid Keshavarz-Nia's Claims of "A Sudden Rise in Slope" as Election Fraud Evidence Election 2020 5
Debunked: Trump's Claim of "1,126,940 votes created out of thin air" in PA Election 2020 8
Debunked: Crowder's "Fraud Week" Title Graphic (and Why it Matters) Election 2020 1
Debunked: Democratic senators complained about 'vote switching' by Dominion voting machines in 2019 Election 2020 2
Debunked: The Democrats are trying to take away freedom of religion Election 2020 6
Debunked: Dr. Shiva's Scatterplot Analysis of Michigan Precincts Election 2020 43
Debunked: Suspicious "Biden Only" Ballots in Georgia Election 2020 3
Debunked: "Nancy Pelosi's long time Chief of Staff is a key executive at Dominion Voting" Election 2020 0
Debunked: Wisconsin Turnout 89% Impossible High [Actually 72%] Election 2020 1
Debunked: Video of Poll Worker "Filling In" Ballots. Election 2020 3
Debunked: Pentagon has Evidence of "Off-World Vehicles Not Made on this Earth" UFO Videos and Reports from the US Navy 14
Debunked: United Nations creates a "NWO" website Conspiracy Theories 2