In the last century, while the United States focused on Mars and the outer planets, the Soviet space program had a tradition of exploring Venus with various probes and landers. Now Russia is planning to pick up where the Soviet Union left off, with an ambitious mission concept called Venera-D that includes a Venus orbiter, a lander, and a surface station. Launch is tentatively planned for late next decade.
Last week the Russian Space Research Institute held a Venera-D Landing Site Workshop in Moscow to move the concept forward. The workshop had two themes. The first was to seek community input on where to land on Venus, and how the various elements of a lander, such as a weather station or seismic probes, should work together. I find it particularly exciting that mission planners are considering adding a variable altitude aerial platform—either an airship or balloon—similar to the “atmospheric station” I floated in my 2013 science fiction novel Voids of Eternity: Alien Encounter (except that my fictional platform had to be piloted by two astronauts, while the one proposed for Venera-D is robotic).
An aerial vehicle would be ideal for investigating the potential habitability of Venus’s lower cloud layer, which was the other main topic discussed during the workshop. The idea that this cloud deck, about 50 kilometers above the Venusian surface, might contain microbial life goes back to Carl Sagan in the 1960s. Since then it has been elaborated upon by several scientists, including some who presented at the Moscow meeting. (Perhaps the most detailed discussion was a 2004 paper by David Grinspoon, Mark Bullock, and others, including myself, in the journal Astrobiology). Not much progress has been made in testing the hypothesis, however, mostly due to a lack of new missions to Venus.
Recent modeling work by Michael Way of NASA’s Goddard Space Flight Center, which was also presented in Moscow, suggests that liquid water might have been available on the surface of Venus for much longer than was previously thought—perhaps for billions of years. This would increase the chances that microbial life arose there. Later, when the surface became completely dry and inhospitable, life may have moved into the clouds as its last refuge.
One question considered during the habitability discussion was the availability of phosphorus in the Venusian clouds. It’s a critical element for life on Earth, and presumably would have to be present on Venus for life to exist. Key insights came from a Russian-language paper—which was new to most of the non-Russian scientists at the meeting—presenting data from the Soviet VEGA missions of the 1980s, which successfully measured phosphorus-containing aerosols at various altitudes in the Venusian clouds.
These revelations—from new modeling and old Soviet spacecraft—boost the argument for microbial life having once existed in Venusian oceans, and perhaps still existing in the lower atmosphere. The only way to find out for sure is to send a mission back to Venus. As of today, the Russian space program is closer to accomplishing this than NASA is. In theory, Venera-D could launch as soon as 2026. But space mission funding is problematic in Russia, as it is in other countries, so it may be a while before we find out whether Earth’s twin is really lifeless.