The Pioneer Venus Multiprobe data weren’t easy to decipher. At first, Mogul’s team only had some tables in a few old publications. NASA released more archival data from the mission, but Mogul said there was little contextual information, such as ground-based test data from the instrument.
The team sought the advice of Richard Hodges, an original mission team member who helped them see the “data within the data,” Mogul tells The Planetary Society. He added: “It was an honor and a rewarding experience to work with him.”
The 1978 LNMS instrument team focused on the most common chemicals they expected to find at Venus.
“The focus on the minor and trace [chemical] species was minimal—that’s what we realized after looking at the archival data and the associated publications,” Mogul said. “We immediately found signals in data that other publications hadn’t discussed or mentioned. That was all we needed for motivation to keep going.”
Their analysis eventually found that Venus’ middle clouds harbor a phosphorus-bearing gas, with phosphine being the best fit for the data.
“No other phosphorus chemicals fit the data as well as phosphine, especially when considering the mild temperatures and pressures in the middle clouds, where many phosphorus species would not be gases,” said Mogul in a press release.
The data also point to “redox disequilibria,” meaning some parts of Venus’ atmosphere are out of balance. This indicates an active chemical process possibly linked to life may be happening, and supports the notion that Venus’ clouds could provide a safe harbor for microorganisms.
In addition to phosphine, Mogul’s team found hydrogen sulfide, nitrous acid, nitric acid, hydrogen cyanide, carbon monoxide, ethane, and potentially ammonia and chlorous acid. Some of these chemicals could also be linked to biological processes.
While this new look at old data offers exciting evidence, Mogul acknowledges that the debate is far from over. However, this systematic back-and-forth allows the public to watch the scientific process play out in real-time.
“There are always mysteries to be solved and I think what we just showed that sometimes old data can reveal new stories,” Mogul said. “This is all a process, and moving forward is what science is all about.”