AILSA CHANG, HOST:
In the iconic opening sequence of the 1960s TV show "Star Trek," the viewer has this feeling of drifting through space, plunging through a field of stars.
(SOUNDBITE OF TV SHOW, "STAR TREK")
WILLIAM SHATNER: (As James T. Kirk) Space, the final frontier...
CHANG: That image - zooming through the stars - is a common visual effect in TV shows and movies about space, but it's a hard vantage point to get in real life because we're all stuck here on Earth. For NASA's New Horizons spacecraft, though, the relative position of the stars is beginning to shift because it has now traveled way beyond our planetary neighborhood on its way to interstellar space. Astronomer Tod Lauer is lead author on a new paper about that, accepted for publication in The Astronomical Journal. Welcome.
TOD LAUER: Glad to be here.
CHANG: So New Horizons launched - what? - almost 20 years ago. Can you just briefly catch us up on what was the original mission of that spacecraft, and what kind of journey has it taken so far?
LAUER: Sure. New Horizons was designed to give the first reconnaissance of the planet Pluto. It was launched in January 2006. It swept past Jupiter for a slingshot out of the solar system. And on the way going out, it picked up Pluto in the summer of 2015 - 10 years ago this month - and then four years later after that, it flew past a Kuiper Belt object, and now, as you said, it's headed off to interstellar space.
CHANG: It's just zooming along.
LAUER: Fourteen kilometers a second.
CHANG: Wow. OK, so where is it now, exactly? What do we know?
LAUER: Right now, it has actually gone beyond most of what we call the Kuiper Belt, which is a zone of frozen objects beyond Pluto. It's roughly 60 times further from the sun than the Earth is and getting about three Earth radii every year further away.
CHANG: Wow, that is so cool. OK, well, the fact that it is so far away has allowed people like you to get a really cool vantage point of the stars from the spacecraft's perspective, right? What does this spacecraft see compared to what people here on Earth see?
LAUER: Well, the main thing - and it's really impressive - is the sky is incredibly dark where New Horizons is right now. So you have stars completely surrounding it - the starriest night you have ever seen and then some. And the nearest stars are starting to shift.
CHANG: And why is that so important?
LAUER: Well, it tells you how far you've gone. Just like "Star Trek," they're traveling across the galaxy, and the stars are streaming past. Well, we've just done maybe the first little, tiny fraction of a frame of that sort of movie, but you look and say, oh, the stars have shifted from here to there - I can actually use that to learn where I am within the galaxy.
CHANG: And that's what I wanted to ask you. Like, why is it so significant that New Horizons has this ability to navigate with the stars, as opposed to some other form of navigation?
LAUER: Well, usually, they use a thing called the NASA Deep Space Network. It's a set of radio telescopes set up on the Earth, and it's excellent at determining how far away spacecraft are and, you know, where they are. And so the question is, can you do this all by yourself, just like being out at sea with, say, losing GPS? You know...
CHANG: Yeah.
LAUER: ...With your sextant, the camera, can you find where you are? And we just wanted to see if we could do this with New Horizons. And it has gone far enough that we can do this. But it turns out, with an accurate camera, you could do this for other spacecraft anywhere in the solar system.
CHANG: Whoa. I love that you brought up the sea because you're right. Yeah, mariners use the stars to navigate the seas. So you think navigating by stars is something that future spacecraft could do, like, if they take longer and longer journeys into space, far beyond the ability of astronomers on Earth to steer the way for them?
LAUER: It might be exactly how you do it. The further away you get from the Earth, the fainter the signals are from the Deep Space Network. If you are going to venture out to the stars on an interstellar voyage, you need to look and see ahead where you're going, and...
CHANG: Yeah.
LAUER: ...What you see are the stars. And so learning how to use them to guide your way is exactly how you're going to explore the galaxy once you leave the Earth.
CHANG: God. That's amazing. Tod Lauer is an astronomer with the National Science Foundation's National Optical-Infrared Astronomy Research Lab. Thank you so much.
LAUER: Thank you. It was a pleasure.
(SOUNDBITE OF JERRY GOLDSMITH'S "STAR TREK: THE MOTION PICTURE - MAIN THEME") Transcript provided by NPR, Copyright NPR.
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