Recent research has revealed that Venus might have looked like Earth for three billion years, with vast oceans that could have been friendly to life. The early Venusian atmosphere was thinner and the young Sun was emitting less radiation, putting Venus in the habitable zone. There is a real possibility that Venus might have been the first habitable planet in our solar system and radically different from the Venus we see today.
Could volcanism have had the same effect on Venus that the Siberian Traps had on Earth 252 million years ago at the boundary between the Permian and Triassic epochs? During this time period, Earth witnessed an extreme mass extinction event that extinguished about three-quarters of all species on land and some 95 percent of all species in the ocean? Volcanic activity on a vast scale has long been debated as a likely trigger of the Permian-Triassic mass extinction.
Phosphine –a Biological Signature?
Last autumn, scientists revealed that phosphine was found in trace amounts in the planet’s upper atmosphere. That discovery promised the slim possibility that phosphine serves as a biological signature for the hot, toxic planet. However, astronomers at Cornell University suggest that traces of the gas phosphine point to recent volcanic activity on Venus rather than a biological indicator.
Phosphine is Us about Geology
The Cornell scientists argue that the unique chemical fingerprint of phosphine supports a different and important scientific find: a geological signature, showing evidence of explosive volcanoes on the mysterious planet.
“The phosphine is not telling us about the biology of Venus,” said Jonathan Lunine, professor of physical sciences and chair of the astronomy department at Cornell. “It’s telling us about the geology. Science is pointing to a planet that has active explosive volcanism today or in the very recent past.”
“Our work only emphasizes how interesting our nearest neighbor planet is in terms of its history and possible geologic activity.The next generation of spacecraft exploration is needed to unveil the true nature of Venus,” Lunine told The Daily Galaxy.
Lunine and Ngoc Truong, a doctoral candidate in geology, authored the study, “Volcanically Extruded Phosphides as an Abiotic Source of Venusian Phosphine,” published July 12 in the Proceedings of the National Academy of Sciences. Maat Mons, a large volcano on Venus, is shown below in this 1991 simulated-color radar image from NASA’s Magellan spacecraft mission.
Volcanism may Inject Phosphine into the Upper Atmosphere
Truong and Lunine argue that volcanism is the means for phosphine to get into Venus’ upper atmosphere, after examining observations from the ground-based, submillimeter-wavelength James Clerk Maxwell Telescope atop Mauna Kea in Hawaii, and the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile.
“If Venus has phosphide – a form of phosphorous present in the planet’s deep mantle – and, if it is brought to the surface in an explosive, volcanic way and then injected into the atmosphere, those phosphides react with the Venusian atmosphere’s sulfuric acid to form phosphine,” Truong said.
Lunine said their phosphine model “suggests explosive volcanism occurring,” while “radar images from the Magellan spacecraft in the 1990s show some geologic features could support this.”
In 1978, on NASA’s Pioneer Venus orbiter mission, scientists uncovered variations of sulfur dioxide in Venus’ upper atmosphere, hinting at the prospect of explosive volcanism, similar to the scale of Earth’s Krakatoa volcanic eruption in Indonesia in 1883. But, Truong said, “confirming explosive volcanism on Venus through the gas phosphine was totally unexpected.”
David H. Grinspoon, Senior Scientist at the Planetary Science Institute, wrote in an email to The Daily Galaxy about the possibility that volcanism could have had the same effect on Venus that the Siberian Traps had on Earth 252 million years ago: “It’s an interesting possibility, but seems very unlikely to me because to make it work you really have to propose an extreme volcanic history and composition. This is plausible, but so is a biological explanation. It’s also possible that the phosphine observation is in error,” Grinspoon observed. “Fortunately we have some upcoming missions that will be able to constrain both the volcanic history and the atmospheric composition, so we’ll have much better data upon which to base our answers to these questions.”