NASA EDGE: Venus Transit with Gordon Chin
The NASA EDGE Hosts speaks to NASA Planetary Scientist Gordon Chin about the 2012 Transit of Venus.
CHRIS: So Gordon, we’re covering this astronomical event, the transit of Venus. It’s really cool that we’re going to see Venus crossing the disk of the Sun. But I guess the question is do we really know a lot about Venus?
GORDAN: We know a lot about Venus. It’s one of the first planets that was visited by spacecraft. In fact, over thirty spacecraft have attempted to go to Venus. About twenty-five of them have succeeded. In fact, this is a planet that has witnessed some landers, so we have actual images. Balloons have flown over the atmosphere of Venus. So, this is a planet that we know quite well, yet there are still very many mysteries left on how this planet works.
CHRIS: What are some of those mysteries about Venus?
GORDAN: We consider Venus to be a sister planet to Earth in the sense that it’s about the same size as Earth, almost identical in terms of its diameter. Also, it was formed at the same time as the Earth in the presolar nebula and also out of the same raw materials yet the planet is so different from the Earth in terms of its environment. For example, Venus spins on its axis in the opposite direction that the Earth does.
CHRIS: Why is that?
GORDAN: We don’t know. It’s the mystery. We don’t understand why that is so. Also, it’s rotating very slowly. Its day is 243 Earth days and it goes around the Sun in 225 days. You can see it’s a very slowly rotating body.
CHRIS: With that slow rotating body, how’s the atmosphere and how’s that all affected?
GORDAN: That’s another mystery on Venus. As you know, Venus has a global cloud cover. If we were to actually fly by Venus and look out the spacecraft window we cannot see the surface anywhere. Another strange fact is this global cloud cover is not made out of water vapor as on Earth but is sulfuric acid droplets.
CHRIS: Which would be dangerous here on Earth.
GORDAN: Which is very dangerous. Another thing about it is the atmosphere is rotating 60 times faster than the planet underneath it. It’s called a super rotation. That’s another mystery. Dynamists have been struggling for over 30 years to try to understand what drives the super rotation of this global cloud cover itself. The other thing about the atmosphere of Venus is it is very thick. On the surface of the planet, if you were to stand on it, the atmospheric pressure is about 90 times that of the Earth’s atmospheric pressure. That’s equivalent to being under the ocean at one kilometer depth or a half a mile. It’s an extremely dense atmosphere at the surface of Venus. And it’s also extremely hot, 900° F, enough to melt lead. Venus is an example of a runaway greenhouse. It is extremely warm.
CHRIS: If you land a lander on the surface, we haven’t had landers that would survive that long on the surface.
GORDAN: In fact, no lander has survived for more than about an hour. It’s been incredibly difficult to make landers operate in this incredibly dense pressure, very acidic atmosphere, and also try to get rid of the heat.
CHRIS: Is there any current technologies, maybe looking at carbon carbon composites, any type of composite technology that you think could survive a little longer than that?
GORDAN: It’s not the problem of surviving in the terms of the structure. We build vessels that go down to the bottom of the ocean.
GORDAN: It’s not that. It’s the heat, how to get rid of the heat, how to be able to operate in, I think, very hostile environment, an environment, which is very difficult to be able to keep the electronics inside from cooking itself to bits.
CHRIS: I guess it wouldn’t really make any sense from a human exploration perspective to send a spacecraft out with humans to orbit Venus to study.
GORDAN: It may be, actually, very interesting to do that. In some ways, visiting Venus is actually easier than going to Mars; orbiting Venus as a trial to orbiting Mars with human exploration. People have talked about that. It’s probably easier to do that than trying to go to some near Earth asteroids which would take a long time. If you time it right, you could get to Venus in about 3 months. That really makes it a voyage which may be very tangible.
CHRIS: Right. As a planetary scientist, if NASA came to you and said, Okay Gordan, we want to have a mission to go back to Venus. What would be your primary area of study on Venus?
GORDAN: It’s interesting that you asked me that because I’ve proposed discovery missions to Venus for the past 10 years. Twice a mission that I proposed called Vesper, which means evening star in Latin, was selected as a competitor in the final round, never chosen. What I would do is try to understand why, how the atmosphere works; try to understand the photochemistry of the atmosphere, try to understand the dynamics of the atmosphere, try to understand the forces which stabilize the atmosphere. Venus has an atmosphere which is primarily 95% CO2. Because it’s so close the Sun that CO2 could be broken down into CO in about 200 years. Why is the CO2 stabilized? Well, we believe it’s stabilized by the same catalytic chemical processes the operate on the Earth to destroy ozone but we don’t have the definitive proof of that. We would like to see how that works. We’re finding potentials for thousands of exoplanets, planets which orbit other stars. We are beginning to find planets, which are Earth size. Now, probably finding an Earth among these extra solar planets may be very difficult. Venus may be the more common objects that we will find. So, trying to understand how Venus works, trying to understand its atmosphere, trying to understand its environment, that’s why doing research on Venus is such an important thing.