Although the surface of Venus reaches temperatures of 900 degrees Fahrenheit (500 degrees Celsius) and contains active volcanoes and atmospheric pressures 90 times stronger than Earth, NASA claims that a floating city could make it in the planet's atmosphere.
According to a NASA internal study, the concept mission to Venus known as Havoc, which stands for High Altitude Venus Operational Concept, involved building a floating city of zeppelins hovering in the planet's atmosphere while being manned by astronauts.
"A recent internal NASA study of a High Altitude Venus Operational Concept (HAVOC) led to the development of an evolutionary program for the exploration of Venus, with focus on the mission architecture and vehicle concept for a 30 day crewed mission into Venus's atmosphere," NASA wrote.
NASA also elaborated on the challenges astronauts would face on that hostile planet.
"Key technical challenges for the mission include performing the aerocapture maneuvers at Venus and Earth, inserting and inflating the airship at Venus, and protecting the solar panels and structure from the sulfuric acid in the atmosphere," NASA wrote.
NASA's website on the Havoc project noted that a mission to Venus would take less time to complete than a crewed Mars mission. NASA also claimed that the environment 50 kilometers up in the atmosphere of Venus was "relatively benign, with similar pressure, density, gravity and radiation protection to the surface of Earth."
Evan Ackerman of IEEE Spectrum elaborated on why it would make sense for NASA to have a floating city in the atmosphere of Venus 50 kilometers above its surface.
"At 50 kilometers above its surface, Venus offers one atmosphere of pressure and only slightly lower gravity than Earth," Ackerman wrote. "The temperature at 50 km on Venus is around 75 °C, which is a mere 17 degrees hotter than the highest temperature recorded on Earth."
Compared to Mars, Ackerman contended that while such conditions on Venus "would be unpleasant for an unprotected human," he thought those aspects are "manageable."
Dale Arney and Chris Jones of the Space Mission Analysis Branch of NASA's Systems Analysis and Concepts Directorate at Langley Research Center in Virginia think that it would make sense for the space agency to go to Venus first and set up shop within its atmosphere. Jones tried to put it in context.
"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 said. "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 elaborated on why going to Venus first has scientific and educational value.
"Venus has value as a destination in and of itself for exploration and colonization, but it's also complementary to current Mars plans," Jones said. "There are things that you would need to do for a Mars mission, but we see a little easier path through Venus."
According to Ackerman, a mission to Mars or anywhere else in the solar system would involve experimenting with things such as long-duration habits, aerobaking and aerocapture, and carbon dioxide processing.
"If you did Venus first, you could get a leg up on advancing those technologies and those capabilities ahead of doing a human-scale Mars mission," Arney said. "It's a chance to do a practice run, if you will, of going to Mars."
Arney added that the atmosphere of Venus "can play a role in humanity's future in space."