Venus is the closest planet to our own, both literally—it's the nearest—and in terms of its size and mass, earning it the nickname "Earth's twin."
But given that our sister world experiences average temperatures of 462 degrees Celsius (864 degrees Fahrenheit), crushing 90-bar pressures, and suffocating clouds of carbon dioxide laced with sulfuric acid rain, it's no wonder that Venus has not inspired the same frontier spirit as say, Mars. Indeed, proposed Venus missions have been repeatedly snubbed in favor of others to the red planet, asteroids, and less wholly nightmarish worlds.
Now, NASA and the Russian Academy of Sciences' Space Research Institute (IKI) are teaming up on a project called Venera-D, which makes the case that Venus is as valuable an exploration target as any alien world, perhaps more so because the planet's runaway greenhouse gas effect, which generates its harsh conditions, can inform our efforts to prevent a similar problem on Earth.
I visited IKI in Moscow on March 1 to learn more about Venera-D and many other ongoing projects. Though IKI is on track to land on Mars, with the ExoMars 2020 rover, long before Venera-D is projected to land on Venus, there was still much enthusiasm for pursuing a new mission to our sister world.
Two weeks after my visit, representatives of NASA, IKI, and the Russian space agency Roscosmos convened there to discuss further collaboration on Venera-D, which was first proposed by Russian planetary scientist Vasily Moroz in 2003.
This Russian/American partnership, formed in 2015, is called the Venera-D Joint Science Definition Team (JSDT). In January 2017, it released a thorough report of the two nations' shared objectives on Venus, which include extended observations of the surface environment over a period of months, precise measurements of atmospheric aerosols and composition, and a solution to the longstanding mystery of atmospheric superrotation, a phenomenon in which wind speeds on Venus outpace the planet's rotation by a factor of 60.
"Right now, [Venera-D] is in a concept phase," said NASA Jet Propulsion Laboratory scientist David Senske, the US co-chair of the Venera-D JSDT, in a phone interview with Motherboard. "It's not a mission yet. We're working on proof of concept, and seeing where we can fit in the 'sweet spot' science."
"The next phase will focus on refining the science, refining how you might capture that science in terms of instruments, and the Russians will be working more in terms of refining what a mission concept looks like," he said.
To that end, IKI planetary scientist Ludmila Zasova, the Russian co-chair of the JSDT, called the March meeting "very successful."
"Venus is like your oven at home on autoclean mode"
"The decision to sponsor the work for the next two years (2017-18) was taken both by NASA and by Roscosmos," Zasova told me over email. "Our efforts were highly appreciated, so we hope that we made one step in the direction of the mission being realized."
At the moment, the earliest possible launch date would be in 2026, Zasova said.
Venera-D would resume the Soviet Venera program that ran from 1961 to 1984, and remains the only spaceflight series to have successfully transmitted pictures and information from the surface of Venus.
It would also build on the Soviet Vega twin missions of the mid-1980s, which included atmospheric balloons and lander components. Russia's rich history of Venus exploration is brought to life in IKI's museum with mockups of its iconic landers and balloons used in past missions.
This latest incarnation is designed to outlast its predecessors by integrating cutting-edge, durable technology into a spacecraft platform that could survive for months, or even years, in the orbital, atmospheric, and surface environment of Venus. In fact, the "D" in Venera-D stands for "Dolgozhivuschaya," meaning "long-lived."
The baseline mission would be an orbiter and a lander, but additional elements might include "an aerial platform with solar batteries flying in the clouds, small long-lived stations (with several months' lifetime) on the surface, and a sub-satellite in orbit," Zasova told me.
This potential aerial platform is called the Venus Atmospheric Maneuverable Platform (VAMP), and is currently being developed by the aerospace company Northrop Grumman. VAMP would be able to spend up to a year gliding above Venus at altitudes of 30 to 45 miles (50 to 70 kilometers) where conditions are surprisingly Earthlike, in contrast to the inferno that lies below.
All this is a welcome change for the Venera-D project, which has suffered repeated delays over the last decade. The team's report notes that the mission was held up by reduced availability of high-temperature electronics that could survive the punishing surroundings on Venus. These systems were in development during the Soviet period, but their production in Russia had lapsed by the time Venera-D was pitched to the Russian Academy of Sciences in the early 2000s.
"Venus is a tough nut to crack," Senske said. "It's like your oven at home on autoclean mode. It really is tough to get down there. It's easier, say for Mars, to do technology for extreme cold, but extreme heat has been a slower evolution over time." Designing rovers like Opportunity or Curiosity, which can rumble along for years at a time in Mars' chilly weather, is a much easier task than building a robot that can withstand the lead-melting temperatures of Venus any longer than the runtime of a standard feature film.
Tibor Kremic, an electrical engineer at NASA's Glenn Research Center, is helping to bridge this particular technological divide. As the lead scientist on Venera-D's Long-Life Station lander, Kremic is working out the kinks of heat-resistant electronic systems that could endure Venus's surface for at least two months—though he said in theory, these stations could operate indefinitely.
"Our goals for Venera D are to try to get at least 60 days because that would allow us to capture one of the day-to-night transitions, and see how conditions may change for the measurements we're making at that time," Kremic told me over the phone. "The orbiter is intended to last for about three years, so if we can get to that, it'd be awesome."
"Could the uncontrolled greenhouse effect transform Earth's climate to a Venus-like one?"
"But anything more than a couple hours is a step forward," he added, referring to the record set by Venera 13, which landed on Venus in 1982, transmitting images and data back to Earth for 127 minutes before perishing from the planet's brutal onslaught of heat, pressure, and toxicity.
The Long-Life Station concept relies on robust silicon carbide as "the backbone of its electronics," Kremic said, as opposed to the silicon systems of the original landers. Early versions of these modules have already been road-tested in Venus simulators at Glenn, with favorable results.
"We've shown that the basic elements last for thousands of hours and we're in the process of developing the more complicated ones, where you can actually take the measurements, process the data, and communicate it," Kremic said.
It's hard to overstate the scientific potential of such extended robotic lifetimes on Venus. Some of the most persistent mysteries in planetary science are hidden behind this world's thick veil of atmospheric cover. Examples include the identity of the so-called "unknown ultraviolet absorber" that eats up UV light in the atmosphere, or the mechanisms governing Venus's aforementioned superrotation effect. The planet's extremely long day period—equal to 243 Earth days—also requires long-lived modules just to watch one full day go by.
The Venera-D team also hopes to understand the planet's enigmatic past, including its potential to have hosted liquid water in its infant years. It may even have been the first life-bearing world in the solar system, and could be a key model for assessing Earth's future habitability, according to Zasova.
"Curiously, the sister-twin planets, Earth and Venus, obtained a similar composition of protoplanetary material at their formation," she told me, "but nevertheless they have a very different atmospheres and surface conditions now. Indeed, we have a comfortable climate for life on Earth and a 'hellish' one on Venus. Could the uncontrolled greenhouse effect transform Earth's climate to a Venus-like one?"
Senske is also intrigued by Venus as a powerful analog to Earth. "The big question is: Why isn't Venus [like] the Earth?" he said. "In order to understand how solar systems form and evolve—and what makes a zone habitable in solar systems—Venus is a key piece of the puzzle."
After years of being passed over in favor of Mars and other missions, "Venus is coming back around," Senske predicted.