And the images we got when we flew by Wild 2 suggests that’s the case, that, in fact, we’re looking at a very much more pristine surface. Well, in the case of Wild 2, it’s only been cooked a few times since 1974, so this meant that we had a good chance when we got to Wild 2 that we would get a sample of kind of a raw comet, a comet that’s not been, you know, slapped around much. It’s a surface that’s been cooked many, many times. Haley’s Comet’s been near the sun probably hundreds of times and so when you go to Haley’s Comet, the surface you see is not the original surface. So it hasn’t lost all the volatiles and the ices and the things that come off a comet when it gets near the sun like most other comets. But in 1974, it almost slammed into Jupiter, just missed it, and that caused - Jupiter bent its orbit into the current one, and so this is a comet that has not been near the sun for probably most of its lifetime and has only gotten near the sun a few times. However, it turns out that even if it had been harder to get to, this is a comet we would have liked to have gone to because prior to 1974, this comet was in an orbit where the closest it got to the sun was Jupiter’s orbit and spent most of its time out by Neptune. And so one of the reasons we went is because we could get there. So it doesn’t take a gigantic rocket motor to get there. The closest it gets to the sun is getting down near the Earth’s orbit. I mean the comet is in an orbit now where the furthest it gets from the sun is Jupiter’s orbit. The more mundane one is it was a comet we could get to. Scott Sandford: Okay, well, there are sort of several reasons why we picked Wild 2 as the comet to go to. And so we basically swept up some of this dust as we went piling through this dust cloud. It’s the dust particles that ultimately make the tail that most people are familiar with. And the coma is the cloud of dust participles surrounding a comet.
But we collected this material by flying a spacecraft at fairly high velocity through the coma of the comet. Scott Sandford: Okay, well, the samples came from a comet called Wild 2, which currently is in an orbit where the closest it gets to the sun is not quite the Earth’s distance from the sun, and the furthest it gets from the sun is all the way out at Jupiter’s orbit. Jesse Carpenter: Tell us where the samples came from and how unique that is. And so if material from these comets was rained out on the Earth after its formation, and we think it was, then this material may have played a role in getting life started because these complex organics that are basically falling out of the sky could have participated in all kinds of chemical reactions that could have led on to much more interesting things like us. So a component of this material could be organic compounds, complex organic compounds. Scott Sandford: Well, I think one of the principle reasons why we want to go to a comet is we think that the material that comets are made out of hasn’t been processed much since comets formed 4.5 billion years ago, when the solar system formed, and as such, they may be one of the best reservoirs in the solar system of the original, primordial stuff from which everything else in our solar system was made. Scott, tell us why would we want to go to a comet to begin with. He’s the lead author of the preliminary findings from the Stardust sample return mission. Today, we have an interview with research astrophysicist Scott Sandford. Launched in 1999 the Stardust spacecraft collected dust particles from the tail of the comet Wild 2 in 2004 and returned the samples to Earth in 2006. Hi, I’m Jesse Carpenter and you’re listening to a podcast presented in three parts from the NASA Ames Research Center. Jesse Carpenter: NASA study finds new kind of organics in Stardust mission samples.
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