Scientists recently announced the discovery of phosphine on Venus, and this compound of phosphorus and hydrogen may be related to life. While efforts to confirm this discovery through Earth observations or even occasional planned spacecraft up close are underway, archived data from a NASA mission to Venus decades ago could hide a lot of exciting validation — and there could be more discoveries in the future.
Phosphine has been found in the atmosphere of Venus, which is evidence of the existence of life on Venus! The news is heartening after years of fruitless searches for extraterrestrial life! However, as a scientific study, in order to validate this finding again, scientists are eager to obtain more data, whether from large telescopes or an entirely new interstellar mission.
Susa Silva
If the presence of phosphine gas can be confirmed again, the next step will be to address the question of its origin, including the possibility that it was produced by some sort of single-celled life floating in the planet's clouds. Susa Silva of MIT, one of the scientists working on phosphine in Venus, said: "If phosphine does exist and it's a sign of life, then it would be a way to start piecing together the biosphere." ”
Many experts believe that the best way to verify Venus' phosphine is to launch an atmospheric probe that can directly sniff out the gas. But such a mission is not an imaginary journey into the future. In fact, humans have launched such probes before, such as the Venus series of probes in the former Soviet Union. NASA has also carried out a similar exploration project, which is the pioneer Venus multiple probe.
Pioneer Venus multiple probe
The Pioneer Venus Multiple Probe, also known as Pioneer Venus 2 or Pioneer 13, is a spacecraft launched by NASA in December 1978 to explore Venus as part of NASA's Pioneer Program. This part of the mission includes a spacecraft launched from Earth, carrying a large probe and three small probes. After separation, the probes penetrate the atmosphere of Venus at different locations and return data as they descend into the planet's dense atmosphere.
On top of pioneers' largest detectors, there is an instrument called the Great Detection Medium Nature Spectrometer (LNMS), which is capable of looking for gases in Venus's atmosphere. But the scientists on that mission focused on molecules such as carbon dioxide, sulfur dioxide and argon.
Now, after another analysis of the data, Laksh Mogur, a biochemistry professor at Caltech, believes that the scientists on this mission underestimated their instrument, which may have found trace amounts of other molecules, including exciting phosphine.
Moghur said: "We were able to extract some data from the literature from about 40 years ago. "His team recently published their findings on the preprint server arxiv." We think we can identify something interesting. We believe there is evidence of the presence of phosphine. ”
Laksh Mogur
Instruments such as LNMS calculate the mass of molecules by measuring the speed at which they hit the detector to identify molecules. Mughal suspects that in a preliminary analysis of LNMS data in the 1980s, scientists prioritized molecules that were already thought to exist in Venus's atmosphere. "They're interested in the overall properties of the atmosphere and how those properties change up and down at high altitudes," he said. ”
However, LNMS instruments may be more sensitive than expected, capable of detecting more molecules, including phosphine. "People don't believe (these molecules) because they don't think they could have appeared in Venus's atmosphere," Mughal said. In the LNMS data, it's easy to overlook subtle evidence of the molecular presence — especially if that person isn't doing a targeted search. More than 40 years later, a shocking revelation has made it clear that what is in this information has been waiting to be discovered.
Susa-Silva notes that if the interpretation of the findings of the data transmitted back by the pioneers is correct, it would be an exciting and rapid validation of the detection of phosphine by her team. And such reconfirmation also suggests that the compound has been in Venus's atmosphere for at least 40 years, meaning there must be some process of replenishing it— biological or abiotic. In other words, it would mean that the newly detected phosphine "isn't just an isolated incident that we accidentally captured," she said.
However, not everyone believes this. Mikhail Zolotov, a planetary scientist at Arizona State University, believes that the data provided by the instrument 40 years ago should not be enough to distinguish phosphating substances detected, for example, phosphine from more common mixtures of phosphorus-rich gases and hydrogen sulfide. In addition, he said, if the LNMS data are true, it means that the gas is much higher than what Susa-Silva's team found. In fact, the conclusion "much higher" is incompatible with the recent discovery of "trace gases." If Mogur and his colleagues correctly interpret the Pioneer detector data, Zolotov said, "we expect the concentration of phosphides to be much higher than astronomers measured, which is also a red flag." ”
Mikhail Zolotov
So far, Mogur and his collaborators have only been able to obtain fragments of information from the Pioneer mission, which correspond only to altitudes of 50 to 60 kilometers above Venus. However, the Pioneer probe actually collects data from an altitude of 90 kilometers all the way to the surface of Mars. If these data can be fully analyzed, and if the presence of phosphine can be confirmed, they can reveal more information about the distribution of this gas in Venus's atmosphere, which may be an important clue to pinpoint its source.
Unfortunately, although physical copies of this information are stored in the NASA Space Science Data Coordination Archive (NSSDCA) at NASA Goddard Space Flight Center, access to the file is currently restricted due to the pandemic.
David Williams, acting head of NSSDCA, said: "We do have some experimental data, but unfortunately, this data is all kept on microfilm and is not easily accessible. "We're currently trying to get permission for one of our staff to digitize microfilm because we've received inquiries about it." If we're lucky, maybe we can start this week. ”
Other archived data may also be useful. Susa Silva is currently observing Venus with an infrared telescope for more neglected evidence of phosphine. And Sanjay Limayer, from the University of Wisconsin-Madison, one of the co-authors of the Mogel preprint paper, said old data from Soviet Venus — though unlikely sensitive enough to detect phosphorus — may contain evidence of phosphorus atoms, which may also hint at the presence of molecular phosphating material. However, he noted that much of the whereabouts of these data are unknown. Still, Limayer said, "There may be someone who has some records." ”
HMS Bepikronpo
Europe's and Japan's Bepi Colombo spacecraft, NASA's Parker Solar Probe, and Europe's Solar Orbiter will soon fly over Venus. Some of them may be looking for phosphine. However, this is only possible. So far, the exact evidence of phosphine on Venus has come from past Earth mission archives, "if these measurements are true, [phosphine] has been around for 40 years," Mogur said, "so there's something making it." "Then the next question is, exactly what made it.