Is a Cloud City Above Venus on the Horizon?

After 35 years since robotic balloons explored the clouds of Venus, a study has found another reason to do it again. (Image courtesy of NASA Langley Research Center.)

The race to explore Mars may be well underway, but a recent discovery in the clouds above Venus has renewed interest in exploring Earth’s hot, gaseous twin. The detection of phosphine, which is produced on Earth via bacteria and microbes that thrive without oxygen, may be the sign needed for NASA to focus more on its High-Altitude Venus Operational Concept (HAVOC) mission.

A newly processed, enhanced image of Venus shows clouds approximately 30 miles above the planet’s surface, perhaps making an ideal location for an exploratory cloud base. (Image courtesy of NASA/JPL-Caltech.)

Although Venus is closer than Mars as they orbit, which makes a trip to Venus and back potentially 100s of days shorter, the heat factor can’t be ignored. With temperatures rising above 464 °C and pressure 89 times higher than that of Earth, landing on the planet isn’t an option. That is where HAVOC differs. It would mean exploring the planet’s atmosphere instead of its surface.

“The vast majority of people, when they hear the idea of going to Venus and exploring, think of the surface, where it’s hot enough to melt lead and the pressure is the same as if you were almost a mile underneath the ocean,” said Chris Jones from the Space Mission Analysis Branch of NASA’s Systems Analysis and Concepts Directorate at Langley Research Center (LaRC). “I think that not many people have gone and looked at the relatively much more hospitable atmosphere and how you might tackle operating there for a while.”

At about 30 miles above the surface of Venus is an atmosphere with lower pressure and gravity not too much less than that found on Earth. Within those clouds, the temperatures average 75 °C. While still hot, it only surpasses the hottest temperature on Earth by 18 degrees. Those conditions present an appealing potential for protected exploration.

Profile of Venus’s middle and lower atmospheres. (Image courtesy of Encyclopædia Britannica, Inc.)

Another factor is that Venus would provide an abundance of solar power without high levels of radiation. According to Dale Arney from the Space Mission Analysis Branch of NASA’s Systems Analysis and Concepts Directorate at LaRC, exposure to that atmosphere would be “about the same as if you were in Canada.”

Those almost Earthlike conditions have scientists looking into the use of orbiters to conduct missions, perhaps resulting in a cloud city above Venus. The ultimate goal of HAVOC would involve five phases: robotic exploration, a 30-day orbit by crewed mission, a 30-day atmospheric crewed mission, a 1-year atmospheric crewed mission, and permanent human presence.

A rendering of what a permanent human presence in the clouds above Venus might look like. (Image courtesy of NASA Langley Research Center.)

Before anyone heads to the clouds, two missions are awaiting final approval from NASA next year. DAVINCI+ would probe the Venus atmosphere to study chemical compositions with multiple spectrometers during a 63-minute descent, while VERITAS would combine radar and near-infrared spectroscopy to penetrate beyond the clouds for a better understanding of the planet’s geology and topography.

Unfortunately, whichever mission is chosen, launch windows can only happen every 19 months. Along with planning, testing and further research, nothing will likely be heading toward Venus until 2026.

Interested in more space exploration? Check out NASA’s OSIRIS-REx Ready for Touchdown Following Final Practice Run.