Author: Nancy Atkinson

ESA’s Venus Express spacecraft will be cozying up to the planet it has been studying for over two years to begin new and more detailed observations of Venus. This week, engineers began executing a series of maneuvers to gradually bring the spacecraft to a new orbit, closer to Venus. In its new, modified orbit the spacecraft will be able to observe unexplored regions and investigate phenomena that were not within its reach before. The maneuvers will be executed through the month of July, settling it into its new orbit by August 4. Venus Express will eventually get close enough to the planet to dip slightly into the atmosphere, testing out its aerobraking capabilities to further alter its orbit, as well as evaluating the density of the upper atmosphere by measuring the drag on the spacecraft with its on-board accelerometers.

Until now, Venus Express has occupied a highly eccentric polar orbit: at its closest point (pericentre), the spacecraft is between 250 km and 400 km from the planet, and at its farthest (apocentre), it is about 66,000 km away. The pericentre is located at 84° north.

This eccentric orbit was designed to facilitate observation of the southern hemisphere for extended periods, while being able to obtain close observations of northern hemisphere and northern polar regions.
The lowering of the Venus Express orbit is the first step in for more ambitious explorations of Venus, especially of its atmosphere.

Venus Express has already found a highly variable quantity of the volcanic gas sulphur dioxide in the atmosphere of the planet. Scientists are trying to determine if this is evidence for active volcanoes on Venus, or by another unknown mechanism affecting the upper atmosphere.

Now, the altitude of the pericentre will now be lowered to between 185 and 300 km. This modification will enable the following science advantages:
• Study of the magnetic field in the northern polar region
• Study of the plasma environment deeper in the ionosphere
• To indirectly deduce the density of the planet’s atmosphere by measuring the force, or drag, exerted by the planet’s atmosphere on the body of the spacecraft as it moves closer to the planet

Venus Express is European Space Agency’s first mission to Venus. Launched in November 2005, the spacecraft arrived at the planet on 11 April 2006 and began science observations within a month. Since then, it has continuously been making new discoveries and revising our knowledge of Venus.

As of April of this year the spacecraft had returned over 1277 gigabits of data to Earth.

Seemingly, people in the space community have a tendency to push the boundaries of thought about all the possibilities that await us in the universe. Case in point: Geoffrey Landis. Landis is a scientist at NASA’s Glenn Research Center who writes science fiction in his spare time. Last week Landis shared with us his ideas for using a solar powered airplane to study Venus.

This week, Landis goes a step farther (actually, several steps farther) with his ideas about colonizing Venus. Yes, Venus, our hot, greenhouse-effect-gone-mad neighboring planet with a crushing surface pressure that has doomed the few spacecraft that have attempted to reach the planet’s mysterious landscape. Landis knows Venus’ surface itself is pretty much out of the question for human habitation.

But up about 50 kilometers above the surface, Landis says the atmosphere of Venus is the most Earth-like environment, other than Earth itself, in the solar system. What Landis proposes is creating floating cities on Venus where people could live and work, as well as study the planet below.

“There’s been a lot of people who have been proposing space colonies, such as colonies that are in free space, separate from any planet,” said Landis. “And I said, well, if you’re thinking that far into the future why don’t we think of some more groundbreaking, or perhaps we should say atmosphere-breaking possibilities.”

50 km above the surface, Venus has air pressure of approximately 1 bar and temperatures in the 0°C to 50°C range, a quite comfortable environment for humans. Humans wouldn’t require pressurized suits when outside, but it wouldn’t quite be a shirtsleeves environment. We’d need air to breathe and protection from the sulfuric acid in the atmosphere.

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.

The biggest challenge would be using a substance resistant to sulfuric acid to form the outer layer of the bubble; ceramics or metal sulfates could possibly serve in this role, but of course, you’d want to be able to see outside, as well. “Just think of the great pictures you could get,” said Landis.

Asked if he has ever thought about terraforming Venus, Landis said, “Oh, yes, of course! That’s one of the reasons I started thinking about the floating cities on Venus. The more you look at Venus, the more you say, ‘oh my goodness, terraforming would be a really hard project.'”

Back in about 1962 when Carl Sagan first talked about the concept of terraforming Venus, it wasn’t known what a challenge Venus would be.

“They didn’t quite know how difficult Venus is, they didn’t know how thick the atmosphere was on Venus and how hot it was,” said Landis. “They knew it had a greenhouse effect, but they didn’t know how bad. But the more we look at the problems, the more we say, goodness, terraforming is a very difficult proposition.”

But Landis thinks Venus already has a very nice environment.

“What I like to say, the problem with Venus is if you define sea level as the place in the atmosphere where it’s the same as Earth, the place of “sea level” on Venus is just too far above the ground.”

While Landis’ plans for a solar powered airplane are a true possibility for an upcoming mission to Venus, his ideas about colonizing that planet are a little more speculative. “This is really just a thought exercise,” said Landis, “an exercise in imagination rather than something we’re likely to do in the near term. I don’t expect people will be building cities on Venus, at least probably not in this century.”

Anyone having visions of Bespin and Lando Calrissian from “The Empire Strikes Back”?

Maybe that should be “Landis” Calrissian.

More information about Geoffrey Landis.