Despite being our closest neighbor in the heavens, the planet Venus still harbors a multitude of mysteries, due primarily to its thick cloud cover, obscuring the planet’s surface from study. Space probes sent to its surface are also only able to glean a scant amount of information: because of the intense heat and pressure at Venus’s surface, most probes fail after less then an hour. Adding to the mystique of the Morning Star is a newly-found wave propagating across the planet’s atmosphere, and the idea that Venus’s dark streaks may hold microbial life.
In April and May of 2016, Japan’s Akatsuki spacecraft recorded a massive, 10,000 kilometer (6,000 mile) bow-shaped wave of bright particles stretching across the surface of the planet, reaching nearly from pole-to-pole. This feature, in-of-itself, was impressive, but it initially baffled the scientists recording it, as it is standing still above the surface. This is odd because Venus’s atmosphere rotates around the planet much faster than the planet itself rotates, rounding the planet sixty times for each Venusian day.
However, this difference in speed may offer an explanation for the presence of the wave: the wave is situated directly over a large mountain region called Aphrodite Terra, that could be generating gravity waves that are disrupting the dense atmosphere as it flows swiftly over the mountains.
"If you have a stream and it’s flowing over a rock, you get the gravity waves propagating upwards through the water. At the surface of the stream, you will see it as changes in height," explains Dr. Colin Wilson, a planetary scientist at the University of Oxford.
"What’s happening here is slightly different, because we’re seeing it in cloud top temperatures. But the air particles are moving up and down, very much as the water particles are moving up and down."
Closer to home, a joint U.S. and Russian research team are preparing a new atmospheric probe to be sent to Venus, called Venera-D, and are looking at including sensors that could look for microbial life in the planet’s upper clouds. Venus’s atmosphere sports a series of otherwise unexplained dark streaks that, for some unknown reason, absorb ultraviolet light.
While the mystery of how these streaks were formed, what they’re made of, or even why they don’t simply blend into the rest of the atmosphere is currently unknown, on possible explanation is that they contain microbes that could exist in the comparatively comfortable upper atmosphere.
“It’s a possibility we can’t overlook,” explains Sanjay Limaye, an atmospheric scientist and a former chair of NASA’s Venus Exploration Analysis Group (VEXAG). “I cannot say that there is microbial life in Venus’ clouds. But that doesn’t mean it’s not there either. The only way to learn is to go there and sample the atmosphere.”