Biological Agent Phosphine Found on Venus

[Ygggdrasil]

Another team attempted to confirm the presence of phosphine in the atmosphere of Venus by examining IR spectra and did not observe signals at the wavelengths expected for phosphine:

A stringent upper limit of the PH3 abundance at the cloud top of Venus
https://arxiv.org/abs/2010.07817

Abstract

Following the announcement of the detection of phosphine (PH3) in the cloud deck of Venus at millimeter wavelengths, we have searched for other possible signatures of this molecule in the infrared range.
Since 2012, we have been observing Venus in the thermal infrared at various wavelengths to monitor the behavior of SO2 and H2O at the cloud top. We have identified a spectral interval recorded in March 2015 around 950 cm−1 where a PH3 transition is present.
From the absence of any feature at this frequency, we derive, on the disk-integrated spectrum, a 3-σ upper limit of 5 ppbv for the PH3 mixing ratio, assumed to be constant throughout the atmosphere. This limit is 4 times lower than the disk-integrated mixing ratio derived at millimeter wavelengths.
Our result brings a strong constraint on the maximum PH3 abundance at the cloud top and in the lower mesosphere of Venus.

 

[sophiecentaur]

That's seems to be to be at least a moderate confirmation of one or more of Fred Hoyle's speculations.

Quote

I think the guy really deserves a retrospective break. At the time he favoured the Steady State solution, he was by no means the only one and the CMBR measurements were only available after he published his views. Not surprisingly, he didn't go down without a struggle. And he did invent the term "Big Bang" (though it was in an attempt to put the idea down.)

Mainstream Science can often be pretty unforgiving of 'good Scientists'. Take poor old Eric Laithwate, who was a very competent Electrical Engineer but just wasn't allowed to suggest that reactionless drive might be needed in order to 'explain' the results of some of his dodgy Maths.

Science is a rough business and shows no sympathy for people who rock the boat. Paradigm changes do occur though but history is written by the winners, as in all of life.

 

[Ian J Miller]

I would be very nervous of assigning a signal at 950 cm-1 to phosphine. Acid chlorides, phosphates, and certain nitrogen-oxygen bonds can give signals in this region, and when talking about the upper atmosphere, as seen in Earth's atmosphere, some rather strange molecules are formed in very low concentration due to UV photochemistry. Phosphine is not the only molecule that could give the signal.

 

[sophiecentaur]

I would be very nervous of assigning a signal at 950 cm-1 to phosphine. Acid chlorides, phosphates, and certain nitrogen-oxygen bonds can give signals in this region, and when talking about the upper atmosphere, as seen in Earth's atmosphere, some rather strange molecules are formed in very low concentration due to UV photochemistry. Phosphine is not the only molecule that could give the signal.

I talked to Emily Darnell Maunder, who was a member of the team. I asked her about the sort of signal to noise ratio for their measurement and she quoted well above 10dB. So that is a Reasonable confidence limit, I would have thought.

 

[Ian J Miller]

I don't doubt they properly recorded a signal. The question is, what caused it?

 

[Ygggdrasil]

I would be very nervous of assigning a signal at 950 cm-1 to phosphine. Acid chlorides, phosphates, and certain nitrogen-oxygen bonds can give signals in this region, and when talking about the upper atmosphere, as seen in Earth's atmosphere, some rather strange molecules are formed in very low concentration due to UV photochemistry. Phosphine is not the only molecule that could give the signal.

The significance is not that they observed a signal at 950 cm-1, it's that the did not observe a signal at that wavenumber (especially not the intensity of signal they would expect to see if phosphine were as abundant as claimed in the Nature Astoronomy paper). This would seem to suggest that either phosphine is much less abundant than claimed or that the signal observed by the Nature Astronomy paper is not due to phosphine.

To quote Encrenaz et al. pre-print:

the detection of at least one other PH3 transition, in the infrared or in the millimeter/sub-millimeter range, is definitely needed to confirm the PH3 detection in Venus.

 

[Ian J Miller]

Yes, the upper limit is significant. I was more concerned with whether there was any? I noticed the factor of 4, but again could it be something else there as well? The something else does not have to be equivalent at both frequencies. We still don't know, and I guess I am simply suspicious of phosphine being there.

 

[sophiecentaur]

I don't doubt they properly recorded a signal. The question is, what caused it?

The thing about spectroscopy is that frequency can be measured with more accuracy than any other quantity (it goes wit time). ‘They’ used a lot of previous data as well and the the probability of another explanation for the (precise) frequency arising any other way was considered to be very low.
It’s a system that’s been used for finding the components of all astronomical objects. If you doubt it’s veracity then you need to doubt an awful lot of other discoveries.
I’m not sure there is actually any alternative explanation for the line.

 

[andrew s 1905]

Yes wavelength is accurately measured but assignments us a different problem. There are many lines in high resolution spectra and a single line is not reliable proof . Hence the need for confirmation. This is standard practice and does not challenge all of spectroscopy.
Regards Andrew

 

[sophiecentaur]

Yes wavelength is accurately measured but assignments us a different problem. There are many lines in high resolution spectra and a single line is not reliable proof . Hence the need for confirmation. This is standard practice and does not challenge all of spectroscopy.
Regards Andrew

That is a reasonable statement but absolute frequency gives an absolute Energy transition and, if there are no other possible candidates for the phenomenon then what alternatives are there? I know that the various series are often used for identifying elements and that can be used when the light levels are very low.

Have there been any challenges, other than yours, though? The practical details are very important here - also the precise values of measurements which were obtained from a vast amount of existing data. The team stopped, once their confidence in the result was high enough. I think the data is all public domain so you could, in principle, do the same analysis yourself. (Domestic data connection might be a bit limiting, I suppose.

I'm always impressed with the apparent certainty that spectroscopy gives us; the numbers seem to be reliable.

 

[andrew s 1905]

If I recall correctly they did consider sulphur dioxide as a possibility but dismissed it. You also have to consider the conditions which can broaden the lines, various relative velocities (wind speed, Earth Venus relative velocity) which can shift the lines so it is not as absolute as you might think.

It may well be PH3, but it could be a line from an unnconsiders molecule hence the need for confirmation. I did see a paper where it was detected in retrospect in a Venus probes data. I don't have the reference to hand.

Many lines in the solar spectrum remain unidentified even today after years of study.

Regards Andrew

PS I think only the reduced data is available and in any case without experience of the telescopes involved and the necessary calibration data it is not possible to check.

 

[Ygggdrasil]

Although I am not too familiar with these fields, I am surprised that the authors could claim detection of phosphine based detection of only a single spectral line, especially since the presence of phosphine on Venus is quite unexpected. Is this standard of evidence common across astronomy? Perhaps this limitation of the paper is why it appeared in Nature Astronomy (a relatively new journal published by a for-profit publisher that was likely looking for publicity) rather than a more prestigious journal.

 

[Ian J Miller]

An infrared signal is generated by an energy transition between two states, usually vibrational states, and in chemistry the frequency is often set by what happens in a functional group, and modifed by "the rest of the molecule". If you check a chart of infrared signal possibilities, you will see that a number of molecules could generate a 950 cm-1 line. You need the rest of the signals to be more certain. What concerns me more is that nitrogen-oxygen species can give signals there, and in the Venusian atmosphere it is unclear what could be generated by photochemistry. I am not saying it is not phosphine, but simply that given the difficulties in forming enough phosphine to be stable sufficiently long to generate that signal I suggest a little caution.

 

[andrew s 1905]

A re analysis of the alma data finds no evidence for phosphine Re analysis
Regards Andrew

 

[Vanadium 50]

Without Alma, the JCMT data is not very convincing. (If you turn it upside down, you see signals at least as significant)

 

[mfb]

Things get worse

The data used to make the discovery of phosphine on Venus in September has been removed, temporarily, from the online archive because of an error in the early processing stages.

It's unclear if this error had any impact on the phosphine measurement, but if people find errors related to data used for unexpected measurements it's always a bad sign.

 

[Vanadium 50]

The sociology of astronomy, where you have an instrument team (considered "mere technicians") who operate the telescope and do the calibration and analysis teams (considered "real scientists") who then do the very final analysis steps, lends itself to these kinds of problems.

 

[mfb]

Particle physics keeps mixing these tasks, but these issues can still happen. OPERA's superluminal neutrinos were a calibration problem. Maybe the communication is better, I don't know astronomy well enough for a comparison.

 

[Vanadium 50]

OPERA's superluminal neutrinos were a calibration problem

One ultimately found by the collaboration, and not any of the hundreds of people outside the collaboration looking at their data.

 

[mfb]

People get more direct with criticism:
No phosphine in the atmosphere of Venus

They say the weaker JCMT can come from SO2 and largely come to the same conclusion as the earlier arXiv submission for the ALMA spectrum (no overlap in the author lists).