5X5 Episode 25

NASA Plans Probe to the Sun
NASA: NASA Plans to Visit the Sun

S: This is the SGU 5x5 and the topic for this week is: NASA plans a trip to the sun. That's right. Not content to study the sun with telescopes and satellites, NASA decides to send a mission to the sun.

R: It's very exciting.

B: But they're only going to go at night.

(laughter)

S: Right.

J: Well how&mdash;how far away are they going to have their ship approaching, and I understand they're&mdash;they're just want to collect particles again, right? They're not like&mdash;

R: It's still going to be seven million kilometers away.

S: Yeah.

R: It's not like it's going into the sun.

S: But only the outer atmosphere, though. And they do want to measure its magnetism as well, not just collect particles. They want to sample the solar wind and they want to directly measure the magnetic field of the sun. And this will get information that we just simply can't get from afar.

E: They also want to measure the high temperature of the sun's outer atmosphere, the corona, and try to figure out why it's more than a million degrees Celsius, as opposed to the six thousand degrees Celsius of the surface of the sun.

S: Uh-huh.

B: I thought they solved that issue, but I guess there's still some mysterious aspects to it. The other big mystery, the one that I wasn't aware of, is that when you get that close to the sun, the solar wind has&mdash;is not really going yet, it's really&mdash;it's not only until you get much farther away from the sun is the solar wind turn into this gale force wind&mdash;

S: Uh-huh.

B: &mdash;that's going out in all directions, but when you get that close it's just not&mdash;there's something that's kicking in and giving it the energy to turn into this coherent solar wind and they're not sure how that's happening, so they're hoping that they'll observe that as well.

S: Now at the distance the probe is going to get, the temperature they estimate will be about 1400 degrees Celsius, so they need to develop a heat shield that can withstand those temperatures. The probe right now is just in the design phase. Nothing physically exists yet, but&mdash;so that was going to be the primarily technical challenge is the thermal shield able to withstand those temperatures.

R: It's also pretty cool that they're using Venus as a sort of slingshot thing. Because of that, we're probably going to learn a lot about Venus as well, just by secondary information.

J: So, Bob, when you say that solar wind&mdash;the solar wind is actually something that can push matter, right? There's enough mass to it?

B: Right. The charged particles emanating from the sun and&mdash;yeah, there's a pressure to it. But also, just the pure&mdash;the photons of light also exert a pressure as well.

J: I would imagine then, it's incredibly difficult to build a ship that can get closer to the sun. I mean, I'm sure every time they get closer, they have different considerations they have to worry about.

B: Yeah, they mention that there's solar panels on the probe. Obviously, they'll be inundated with energy, but when it gets too hot, they actual will fold back and be covered by the heat shield if it gets too nasty. And I believe they're also planning on inserting it into orbit around the sun at a key time. It's gonna&mdash;I think it has a seven-year life span, this probe&mdash;

E: It's a solar cycle, right?

B: &mdash;and it will&mdash;yeah, its end of life is planned to be when the sun should be at the tail end of the solar cycle, where it's really going to be energetic and it might see some real&mdash;some real crazy stuff, so that could be interesting.

S: Something to look forward to; they plan on launching this probe in 2015, so seven years from now. And as Bob said, it's a seven-year mission. This is, I think, a very cool potential mission. Interestingly, just recently the presidential candidates were talking about their plans for space exploration. John McCain announced that he thinks that NASA should put a man on Mars, which&mdash;

B: Really?

S: &mdash;sounds very&mdash;yeah, I mean, that's&mdash;it's always an interesting dilemma. It certainly would be extremely cool to go to Mars, but that would be an extremely difficult and expensive mission that would eat up a lot of resources. And missions like this solar probe, that's the kind of thing that would be... that would be hurt by that and that would&mdash;it would suck the money out of all these other things NASA is doing, like the solar probe. So that would be the downside to it. I know a lot of astronomers, like Phil Plait, blogged about this think that it's just not the right time to go to Mars because for that reason and also it would probably end up being a one-off mission. We'd go there and we'd come back and he thinks&mdash;and I agree&mdash;that we should focus our effort on not only continuing to do the science, like this probe, but also to achieve a permanent presence&mdash;human presence, in space, for example, by building a Lunar base. I think&mdash;he thinks, and I agree&mdash;that would be a much better next big project to do rather than just a one-off to Mars.