NASA says it has a vision for future manned science missions to Venus -- a vision that includes zeppelins and a floating cloud city.
While the surface of the second planet from the sun is a sulfurous, corrosive landscape in which no human could survive -- a global greenhouse effect has created surface temperatures of almost 900 degree Fahrenheit with crushing pressures -- at an altitude of around 30 miles there are cloud layers with about the same atmospheric pressure as Earth, with comparable gravity.
That could be the target for a manned mission using airships and floating habitats, NASA researchers Dale Arney and Chris Jones say.
"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," Jones says. "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."
Jones and Arney have proposed a High Altitude Venus Operational Concept (HAVOC) mission that would first send a 100-foot-long autonomous unmanned airship to carry out initial observations in advance of a secondary manned mission.
That mission would see two astronauts working in a cabin slung below a slightly larger helium-filled and solar-powered airship.
A series of mission of increasing length could eventually lead to a permanent science outpost in a floating cloud city, they propose.
Venus, unlike Mars, has sufficient atmosphere to protect astronauts from harmful radiation, and being even closer to the Sun than the Earth there's plenty of sunlight above the cloud layers for solar power.
In addition, a trip to Venus would take less time than a mission to Mars, say Jones and Arney, working at NASA's Systems Analysis and Concepts Directorate at Langley Research Center in Virginia.
While a journey to Mars and back would take between 650 and 900 day, a round-trip to Venus would take only 440 days.
The logistics of getting a 100-foot airship to Venus are daunting, the researchers acknowledge, especially for the manned mission.
The airship, folded up inside a spacecraft, would be sent first, and a human crew would follow in another habitat capsule to link up with the airship in orbit around Venus.
The rest of the mission would, of course, take place above as opposed to on Venus.
"Traditionally, say if you're going to Mars, you talk about 'entry, descent, and landing,' or EDL," says Arney. "Obviously, in our case, 'landing' would represent a significant failure of the mission, so instead we have 'entry, descent, and inflation,' or EDI."
Once the airship was fully inflated and floating around 30 miles above the surface, it could take advantage of winds at that altitude to circle Venus every 110 hours or so while the crew conducts science operations, he says.