Since the discovery of a chemical called phosphine on Venus was announced in September last year, the scientific community has been in a tizzy. Scientists have published articles back and forth, trying to discredit or strengthen the claim.
With two new papers landing this week, some claim he is biting his nails in the phosphine coffin. However, we suspect that the detection will continue to be examined and discussed for some time.
What is the real deal? Read on for a brief introduction.
Phosphine to Venus? Why is it important?
The discovery itself is quite fascinating. Using two different instruments at different times: the James Clerk Maxwell Telescope (JCMT) in 2017 and the Atacama Large Millimeter / Submillimeter Array (ALMA) in 2019, a team led by astrobiologist Jane Greaves of Cardiff University in the UK detected the spectral signature of a chemical called phosphine in the Venusian atmosphere, at 20 parts per billion. The findings were published in Nature Astronomy.
As reported then, here on Earth, phosphine has been found in abundance in anaerobic (low-oxygen) ecosystems. It is found in swamps and muds, where anaerobic microbes thrive. It is found in the intestines and, well, in the farts. Somehow, anaerobic microorganisms produce phosphine. And Venus clouds are anaerobic.
Although Greaves and his team ruled out many possible pathways for the formation of abiotic Venusian phosphine, they were very careful in pointing out that there could be other ways to present the chemical. On the one hand, here on Earth volcanoes produce phosphine and we have evidence that Venus is still volcanically active. (A volcanic origin was later found plausible in another prepress.)
Be that as it may, the detection was fascinating, but the mention of a microbial origin provoked much speculation and follow-up from examinations by other scientists.
What happened next?
Well, it all got a little complicated. First, a team of scientists examined historical data from Venus and found that the Pioneer spacecraft may have detected phosphine by 1978. This paper has not yet been accepted for publication. Another, presented in the magazine Science and not yet peer-reviewed, he claimed to have detected the amino acid glycine (a building block of proteins) on Venus.
Other scientists began examining the data. Three separate articles: one since it was published in Astronomy and astrophysics on ALMA data, another published in Monthly notices from the Royal Astronomical Society in the JCMT data, and in the other reanalysis of both data sets and still pending peer review, no significant detection of phosphine was found in the Venus atmosphere.
It then turned out that there was an error in processing the data from the ALMA observations. Greaves requested that the data be reprocessed; these reprocessed data were made available to the public in November 2020.
Greaves and his team analyzed the new data and found that they could still detect phosphine on Venus, but in lower amounts: an overall average of 1 to 4 parts per billion, with localized peaks of 5 to 10 parts per thousand millions.
Since sulfur dioxide and phosphine absorb radiation near the 266.94 GHz frequency, some suggested that Greaves and his team may have detected sulfur dioxide (also produced by volcanic activity) and not phosphine. In their new article, Greaves et al. discarded sulfur dioxide. The spectral absorption line interpreted as the chemical fingerprint of phosphine, they said, was too wide to be sulfur dioxide, and Venus was not enough to produce the observed signal.
This was followed by a third paper by Greaves and his team advocating the robustness of the phosphine signal.
Okay, why go back to the news now?
Two new articles have been dropped, one of which was published in The Astrophysical Journal Letters, and the other of which has been accepted for publication in The Astrophysical Journal Letters, reanalyzing the data. Both roles contribute to phosphine assembly.
The first paper reanalyzed the two ALMA datasets, before and after they were reprocessed. The computer found a spectral line at 266.94 GHz in the previous data set, but had no significant signal after reprocessing. They also found that sulfur dioxide could appear in at least 10 parts per billion and not be detected by ALMA, suggesting it could be more abundant than Greaves and his team thought.
The second paper used data from decades of observations of Venus to model the conditions of the Venusian atmosphere and determine how phosphine and sulfur dioxide would behave. They found that the 266.94 GHz signal was better suited to an origin at about 80 kilometers above sea level, above cloud cover, rather than 50 to 60 kilometers, as proposed by Greaves and his team. .
At this altitude, phosphine would not last long, so the best explanation would be sulfur dioxide, they concluded.
Is this the end? Is Venus Phosphine Detection Dead?
Not even close! For starters, Greaves and his team are likely to respond to new work, which will lead to more responses, with more simulations and modeling, and even experimentation to determine what the possibilities and probabilities are.
Also, nothing we have seen so far is conclusive. It is more than likely that the only way to end the controversy is by making more detailed observations with more powerful instruments. Maybe we’ll wait a while for that. There are several missions proposed to Venus in progress, but there is often a long time between proposal and execution.
However, this is science at its best. Here is a “true” and a “false.” Either there is phosphine in Venus or not. Scientists will use their creativity to try to solve the problem, which will lead to refined analysis techniques and tools.
Finally, we will learn the truth. And whatever that truth may be, it will teach us something new about our Universe.