Even robots die quickly on Venus.
The most long-lived of the 10 Venusian landers, the Soviet Union's Venera 13 probe, lasted two hours before succumbing to pizza oven-like temperatures of some 870 degrees Fahrenheit (465 degrees Celsius) and the crushing surface pressure of 1,350 psi — which The Planetary Society describes as "like having a small car sitting on your thumbnail." Even so, there's an ongoing scientific debate as to whether this now-hellish world was once hospitable, perhaps harboring great oceans like Earth.
New research, published in the science journal Nature Astronomy, concludes the answer is no. And in the search for potential life in the cosmos, the findings suggest Venus-like planets orbiting on the edge of a solar system's zone of possible habitability may not be good places to sleuth for livable worlds.
"We would have loved to find that Venus was once a planet much closer to our own, so it’s kind of sad in a way to find out that it wasn’t, but ultimately it’s more useful to focus the search on planets that are mostly likely to be able to support life — at least life as we know it," Tereza Constantinou, an astronomer at the University of Cambridge, said in a statement.
Today, planetary scientists suspect that scorching Venus is an active, erupting world, with lava pouring down some of its volcanic slopes. The surface is clearly inhospitable for life. But why don't these researchers think this planet — a rocky world about the same size of Earth — could have once hosted inviting environs, billions of years ago?
The answer lies in the world's atmosphere.
If Venus was once a watery, habitable world, the composition of water in the planet's erupting gases would reflect this past history. "To keep the Venusian atmosphere stable, then any chemicals being removed from the atmosphere should also be getting restored to it, since the planet’s interior and exterior are in constant chemical communication with one another," Constantinou explained.
On water-rich planets, like Earth, surface water is recycled into the planet's interior and outgassed from volcanoes. Nearly 80 percent of Earth's volcanic gases are steam. But the researchers' analysis — calculated from Venus' observable atmosphere and calculations of how gases break down on Venus — found that its volcanic gases contain at most six percent water. That's an extremely dehydrated interior, and points to a profoundly dry Venusian past.
A looming NASA mission will confirm the findings — or possibly challenge them — in 2031. The space agency's DAVINCI spacecraft — short for Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging — will drop a three-foot-wide titanium sphere through Venus' thick clouds. Over the course of just an hour, the probe will ingest gases, run experiments, show us what Venusian mountains actually look like, and dramatically improve our understanding of Venus.
"Venus has always been this enigmatic sister planet," Jim Garvin, who leads NASA's DAVINCI mission, previously told Mashable. "Why doesn't Venus look like Earth?" he wondered.
It's possible — though just a hypothesis — that microbial life could sustain itself high up in Venus' temperate atmosphere where scientists have detected hints of phosphine, a potential indicator of biology. But until NASA's probe plummets through the Venusian atmosphere, the nearby planet will largely remain an enigmatic place.
