Scientists who want to understand what's beyond our solar system have designed an interstellar spacecraft that could go out farther and faster than the famous Voyager probes.



NASA's two Voyager spacecrafts launched in 1977. They've been traveling for so long that they have left our solar system. Amazingly, they still talk to Earth. But of course, their hardware can't last forever, so NASA is trying to figure out what to do once they can't communicate anymore. Here's NPR's Nell Greenfieldboyce.

NELL GREENFIELDBOYCE, BYLINE: The Voyagers were originally built to last about five years. Their mission was to visit Jupiter and Saturn. But since they kept working, they saw Uranus and Neptune, too. They've done all that by the time Stella Ocker was born 25 years ago.

STELLA OCKER: I certainly didn't know much about it when I was growing up. I think I'd heard vaguely about the Golden Records.

GREENFIELDBOYCE: Ah, the Golden Records. One was put on board each spacecraft because scientists knew even if the instruments died, these probes would keep moving farther out into space. They might even bump into some aliens.


UNIDENTIFIED CHILD: Hello from the children of planet Earth.

GREENFIELDBOYCE: The records contained greetings in many languages, plus a collection of Earth sounds.


GREENFIELDBOYCE: Like that train, a barking dog, a kiss. The Golden Records are now just a part of what Ocker knows about the Voyagers. She's a graduate student at Cornell University, and her research relies on data that the spacecraft are still sending back. Voyager 1 is over 14 billion miles away. Voyager 2 is more than 11 billion miles away. Ocker says, to the casual observer, it would look like they're moving through black nothingness.

OCKER: The interstellar medium seems like it's empty, but it's really not. It's full of gas and dust and cosmic rays, energetic particles.

GREENFIELDBOYCE: She says this mysterious territory is important for understanding our own solar system, the universe.

OCKER: There's still huge gaps in our knowledge that can really only be filled by direct sampling.

GREENFIELDBOYCE: The Voyagers have been doing that. Unfortunately, their plutonium power source is ebbing away.

RALPH MCNUTT: We're looking at which instrument gets to have all of their heaters turned off first because we're just flat running out of power.

GREENFIELDBOYCE: Ralph McNutt works at the Johns Hopkins University Applied Physics Laboratory.

MCNUTT: I'm still on the Voyager science team (laughter). I think I'm the youngest one on the Voyager science team.

GREENFIELDBOYCE: At least the youngest who's been around since its beginning. He's 68 this week. He says the Voyagers will run out of power in nine years or so. That's why NASA recently asked McNutt and a team of scientists to make plans for a successor mission. The team has come up with a reasonably priced practical spacecraft, one that relies on technology that's either tried and true or already far along in development.

MCNUTT: And right now we're looking at, pragmatically, being able to go about twice as fast as Voyager 1 and plan for lasting at least 50 years, and that'll get us out to about 375 astronomical units.

GREENFIELDBOYCE: Three-hundred-and-seventy-five astronomical units is more than twice as far as Voyager 1 is, and this new spacecraft would have better instruments.

MCNUTT: A lot of things that we know now that it would have been nice to have had on Voyager, but the technology either didn't exist or Voyager was a 4-1/2-year mission to Jupiter and Saturn, so why would you fly those things?

GREENFIELDBOYCE: Remember; it's just a happy accident that the Voyagers stayed alive long enough to send back information about interstellar space. This new probe, in contrast, would be deliberately designed to go the distance. It would have the longest planned duration of any NASA mission ever. Fifty years would be the minimum. McNutt thinks it might talk to Earth for more than a century. Now, a mission that long is going to have to cope with all of its technology becoming obsolete, to say nothing of its people. Janet Vertesi is a sociologist with Princeton University. She says that the team contacted her and basically said...

JANET VERTESI: Hey, we're planning this mission. It's going to the interstellar medium. We're probably all going to be dead by the time it gets there, and so we figure we probably need a sociologist.

GREENFIELDBOYCE: She's using her expertise to help them think through how and how often parts of the mission will need to be handed off to members of a younger generation - to someone like Stella Ocker, that student who's using Voyager data to work on her Ph.D. Ocker says if NASA decides to fund and build this spacecraft, it could launch around 2036. She'd be in her 40s.

OCKER: And then it wouldn't reach interstellar space for another 15 to 20-ish years. So already we're talking about more of my late career, really (laughter).

GREENFIELDBOYCE: Still, she's really hopeful NASA will give it the green light. She'd also love for it to carry some kind of contemporary take on the Golden Records, some kind of time capsule that reflects the planet Earth and humanity as it is today.

Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.