More on cloud cities 50 km above the surface of Venus from Geoffrey Landis

universetoday.com. Basically, it's the idea of creating floating cities in the clouds of Venus, as the area 50 km above the surface of the planet has the same temperature and atmospheric pressure as sea level here on Earth. Here's a short summary of the advantages of going to Venus first over Mars:

• Closer to Earth (4 month travel time) and more frequent launch windows (every 1.6 years versus 2.1 years for Mars)
• Gravity on Venus is almost the same as that on Earth; on Mars it's only about a third.
• Atmospheric pressure is the same as on Earth, which means you'd only need an oxygen tank when doing anything outside (or if a rupture ever occurred), but not a pressurized area. That means that any habitat ruptures on Venus wouldn't spell instant death like they likely would on Mars.
  
• The atmosphere protects people from the sun's radiation. On Mars there is no magnetosphere so radiation is a more difficult problem.

Some difficulties would be:

• We don't know enough about the atmosphere yet to know whether it would be completely safe. Some parts of the atmosphere have lightning and wind speeds reach up to 400 kph up in the clouds.
• The clouds are acidic so any environment would need to be protected from this.
• No chance of going to the surface which may be a bit depressing.

Here's part of what the article on space.com says:

It's not easy to find comfortable places to stay elsewhere in the solar system. However, Geoffrey Landis, a scientist at NASA's Glenn Research Center, suggests that Venus might be a good place to look.

I know what you're thinking. Venus? Surface temperature of 490 degrees Celsius with about 92 times the atmospheric pressure of Earth's surface? Doesn't sound very hospitable.

One note: surface temperatures and atmospheric pressure are that high only around 'sea level'. Maxwell Montes, the highest location on Venus, is around 11 km above the surface which gives it a temperature of about 380 degrees Celsius and atmospheric pressure 45 times that of the surface of Earth. Still hellishly hot, but sending a rover to a more mountainous location on Venus would be infinitely more doable than way down where the pressure and temperature is that much higher.

Back to the article:

However, Landis, a science fiction writer in his spare time, suggests that we think a bit outside the box. In a recent interview, he suggested building a city in the clouds about 50 kilometers above the surface.

At that altitude, the atmosphere of Venus is at its most Earth-like. The atmosphere has an air pressure of about one bar and the temperature ranges in the 0-50 degrees Celsius range. You'd need breathing apparatus, but probably not a space suit.

And the most important point is that of staying afloat. How does one stay up in the atmosphere of Venus? It turns out that it would actually require no effort whatsoever on our part:

In looking at Venus, the fact that struck Landis the most is that Earth's atmosphere of nitrogen and oxygen would actually float in Venus' atmosphere of carbon dioxide. "Because the atmosphere of Venus is CO2, the gases that we live in all the time, nitrogen and oxygen, would be a lifting gas," he said. "On Earth, we know to get something to lift, you need something lighter than air. Well, on Venus, guess what? Our air is lighter than air, or at least lighter than the Venus atmosphere."

So, create a bubble, fill it with Earth-like atmosphere, and it would float on Venus. "If you could just take the room you're sitting in and replace the walls with something thinner, the room would float on Venus," said Landis.

Since anyone going to Venus needs to breathe Earthlike air, we would already be able to float.


So what's the first step? Sending a solar flyer to Venus to explore this area. Since the rotation of the planet is so slow a solar flyer can stay in full sunlight 24 hours a day, staying at about 65 km above the surface, diving down to about 50 or 40 km for short trips, measuring the planet in extreme detail and telling us about exactly what the area there is like. After that we can decide whether it would be in our best interests to try to go to the next step.



Supplement: Surface temperature and atmospheric pressure on Venus by altitude (everything including the image created / written by me for Wikipedia to get it in the did you know...? section quite some time ago by the way):

Height (km)	Temp. (°C)	Atmospheric pressure (x Earth)
0	462	92.10
5	424	66.65
10	385	47.39
15	348	33.04
20	306	22.52
25	264	14.93
30	222	9.851
35	180	5.917
40	143	3.501
45	110	1.979
50	75	1.066
55	27	0.5314
60	-10	0.2357
65	-30	0.09765
70	-43	0.03690
80	-76	0.004760
90	-104	0.0003736
100	-112	0.00002660