A report by Keith Cooper in Astrobiology Magazine says that US and Russian scientists may search for life on Venus by sending a balloon or glider into its atmosphere in 2025.

The mission is called Venera-D, which has been on-and-off-again for quite a while. But back in 2015, after a hiatus in its development, the US and Russia began discussing the project again. And the mission could be used to study dark streaks in the Venusian atmosphere, which may have a biological origin.

There’s growing evidence that Venus once had a habitable environment, with research suggesting it supported oceans on its surface billions of years ago before it went through a runaway greenhouse effect that turned it into the hottest planet in the Solar System.

Today, Venus is a hellish world with a surface temperature of 462°C (864°F), sulfuric acid rain, and a surface pressure comparable to standing at the bottom of the ocean owing to its thick atmosphere. Between 50 and 60 kilometers (31 and 37 miles) above its surface, though, there exists a band in the atmosphere with a temperature and pressure similar to Earth, boasting some of the most Earth-like conditions of any planet.

And in this band, scientists have found dark streaks – regions absorbing more ultraviolet light than others – that have an unknown origin. One proposed theory is particulate matter mixed into the clouds. A more exciting theory, though, is that the streaks are the result of biological activity from microbial life lofted high into the atmosphere.

^{Artist's impression of a proposed aerial vehicle to explore the Venusian atmosphere called the Venus Atmospheric Maneuverable Platform (VAMP). Northrop Grumman}

“Finding life at high altitude in the atmosphere of a planet would make sense. After all, microbes have been found at similar heights in Earth’s atmosphere,” writes Cooper, who spoke to a member of the Venera-D team, Sanjay Limaye from the University of Wisconsin. “Life could potentially survive in this zone [50 to 60 kilometers high] where the dark-streaking UV absorber is found.”

Venera-D would potentially consist of some sort of aerial vehicle to explore this region, in addition to a small sub-orbiter. According to Cooper, the former would be either a balloon or a solar-powered unmanned aerial vehicle (UAV). A UAV, gliding through the atmosphere between areas of high pressure, would have a better chance of studying the Earth-like band of the atmosphere than a balloon.

Sending a balloon into the atmosphere of Venus would not be unprecedented – Russia did just that with its Vega 1 and 2 missions in the 1980s, following on from the successful Venera landers. But a UAV would be unique, giving us a fascinating insight.

Whether this mission will see the light of day isn’t clear, with a report expected this month and a decision at the end of the year. But if it does, well, things could get rather exciting.

(H/T: Astrobiology Magazine)