There’s nothing like a good old-fashioned science fight. If the discovery in question is one of the most public and intriguing of the past year, it is sure to get even more interesting. A team of scientists led by Andrew Lincowski and Victoria Meadows at the University of Washington (UW), involving members of various NASA laboratories and other universities, has questioned the recently announced discovery of phosphine in the atmosphere of Venus Year. Their explanation is much simpler: it was most likely sulfur dioxide, one of the most abundant materials that are already known to be in the atmosphere of Venus.
Your model takes into account two important correction factors for the original study. First, the location was corrected in the Venusian atmosphere. The signal that phosphine shows was actually observed. Second, corrected for the total amount of sulfur dioxide present in Venus’ atmosphere at the time of the observations.
Maat Mons is shown in this computer-generated three-dimensional perspective of the surface of Venus. This NASA Magellanic image was published on April 22, 1992.
Photo credit: NASA
The observations used as the basis for the original paper announcing the discovery of phosphine used two data sources, the James Clerk Maxwell Telescope (JCMT) in 2017 and the Atacama Large Millimeter / Submillimeter Array (ALMA) in 2019 Both are radio telescopes. and they detect the presence of various materials by monitoring the frequencies at which their signal is absorbed by their observation target. Different frequencies correlate with different materials, so researchers can use a little fancy math to differentiate between different materials in their observation goal.
Unfortunately, some materials are very close to one another in their absorption spectra. Sulfur dioxide and phosphine are two of these materials – both are very close to 266.94 gigahertz. Originally, the team saw a very large drop in this frequency in the JCMT data, suggesting it was being absorbed by something, but it was unclear whether it was phosphine or sulfur dioxide.
Video from UT about the discovery of phosphine on Venus.
To eliminate candidate sulfur dioxide, the team turned to data from ALMA to observe wavelengths at which only sulfur dioxide would have an effect. They found the presence of sulfur dioxide, but not high enough to account for the signal seen in the JCMT data several years earlier. Hence, they concluded that the JCMT signal was caused at least in part by the presence of phosphine.
This realization has already sparked numerous debates in the scientific community. When the UW researchers tried to prove this finding, they noticed something in the JCWT data that the original team either seemed to misinterpret or overlook. The shape of the waveform at 266.94 GHz indicated that the data collected by the telescope actually did not come from the cloud layer of Venus, as the original team suggested. Instead, it came from Venus’ upper atmosphere, about 50 miles from the planet’s surface.
The James Clerk Maxwell Telescope.
Photo credit: www.jach.hawaii.edu
This distinction is important for a number of reasons. Most importantly, phosphine is extremely fragile at these altitudes as it is much more likely to be destroyed by the radiation present at that altitude. The UW team calculated that Venus needs to pump 100 times more phosphine into its atmosphere than the Earth pumps oxygen from all of the photosynthesis that takes place on its surface in order to maintain the levels of phosphine found in the original paper.
That looks like an unlikely scenario. However, the UW team found another complicating factor in the original dataset. The amount of sulfur dioxide in Venus’ atmosphere was likely significantly underestimated in the ALMA data.
Two of the 12-meter antennas of the Atacama Large Millimeter / Submillimeter Array (ALMA) look up into the sky at the observatory’s Array Operations Site (AOS).
Photo credit: ALMA
ALMA can detect gases almost anywhere on its observation target. While this has some significant advantages, the problem is that gases that are more common, such as sulfur dioxide on Venus, actually give off weaker signals than point sources concentrated in a specific area.
This effect is known as “spectral line thinning” and does not affect other telescopes such as the JCMT. UW researchers recalculated the amount of sulfur dioxide originally found in the JCMT data using adjusted values for the ALMA data to correct for the dilution of the spectral lines and found that the entire JCMT signal was at 266 , 94 GHz could only be explained by sulfur dioxide.
Image of the infrared glowing Venusian atmosphere, captured by Akatsuki.
Image credit: JAXA
These results suggest a much simpler rationale for the presence of phosphine on Venus – that it actually isn’t, and it was simply a biased reading of sulfur dioxide that led to the signal that caused so much excitement last year. In honor of the original team, they asked other scientists to review their data and validate or invalidate their results, just as the scientific method requires. This is one of the best things about science battles – they are based on objective facts rather than individualized opinions, and personal animosities usually stay out of the discussion as they appear in this dissenting paper.
The results of these differences of opinion usually also lead to a better understanding of our universe and our place in it, and that certainly seems to be the case here. We might also be able to save millions of dollars tracking a phantom signal from a chemical that didn’t exist at all. Either way, the scientific method is supposed to work – well done by both the original reporting team and the UW team.
Learn more:
UW: Alleged phosphine on Venus is more like ordinary sulfur dioxide, a new study shows
arXiv: The alleged evidence of PH3 in the clouds of Venus agrees with the mesopheric SO2
UT: Maybe volcanoes could explain the phosphine in Venus’ atmosphere
NBC: “Signs of life” on Venus could only be ordinary sulfur gas.
Mission statement:
Image of Venus captured by Mariner 10.
Photo credit: NASA / JPL-Caltech
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