The surface of Venus is too hot to support human habitation so, instead the United States’ National Aeronautics and Space Administration (NASA) is researching at least one option of creating a city suspended above the planet, in the Venusian atmosphere. The High Altitude Venus Operational Concept (HAVOC) looks at floating a human colony in Venus’ sky using blimp technology. The purpose of the spacecraft would be exploration of the brownish-red-surfaced planet.

HAVOC is part of NASA’s Systems Analysis and Concepts Directorate. It is an attempt to find a new way to explore Earth’s closest neighbor. Some refer to Venus as Hell, as previous spacecraft on the planet’s surface survived no more then two hours. The mean temperature on Venus’ surface is 462 degrees Celsius (863 degrees Farenheit), volcanoes possibly number over 1 million, and clouds in the sky are sulfuric acid. In addition, atmospheric pressure at the surface is almost twice that on Earth.

Although several projects have been designed actuated to explore Venus robotically, HAVOC’s city-in-the-sky project would house humans. Thirty miles above Venus’ surface (and its hellish conditions), the main physical feature of HAVOC, said co-creator and leader Dale Arney, would be a blimp 13 meters in length. At that altitude, the atmospheric pressure would be similar to Earth, but the temperature would still be 165 degrees F. On- and off-board systems would be powered by solar panels on the top of the blimp, taking advantage of the planet’s close range to the Sun. HAVOC would float above Venus’ acidic clouds for approximately 30 days, giving crew the same time to gather research data about the Venusian atmosphere.

Arney’s co-creator is Chris Jones, who said that the 30-day mission explored by the HAVOC study would be a first step toward the ultimate goal of a more permanent, human-populated, “cloud city” above Venus. HAVOC is about understanding what “an initial, very short-term mission would look like.” Then, “very notionally,” they looked at what could be built beyond that, moving toward a more permanent human presence.

The primary focus was to get an understanding of the kind of technology that would be required. The object, Jones said, was “mainly to do the science and test out the technology it would need in order to enable those kinds of missions.”

Although very different planets, missions to Venus could be used for learning about later journeys to Earth’s second-closest neighbor, Mars. Utilizing either existing or around-the-corner technologies, trips to Venus would take 440 days while a journey to the red planet would be 500 days or more. One striking difference between the two would be when astronauts would be able to return to Earth. Under the HAVOC / Venus scenario, astronauts could, if needed, abort their mission immediately after arrival and be returned to Earth. No such option would exist for Mars missions, however. Any return would require the Mars crew to wait patiently on the surface until the correct planetary alignment occurred.

Michael Finneran, a public affairs officer with NASA’s Langley Research Center, said it could be some time before humans are sent to Venus. He described the HAVOC concept as “visionary” and that no funding proposals have been created. If, at some point, his agency decided to pursue sending humans to Venus, “many concepts would be examined over a period of time before one was selected.”