spaceSpace and Physics

One Year On From New Horizons, We Spoke To The Man Behind The Daring Mission To Pluto


Jonathan O'Callaghan

Senior Staff Writer

Alan Stern (left) celebrates with his team, one year ago today. NASA/SWRI

One year ago today, you may remember the little news story that New Horizons became the first spacecraft ever to visit Pluto.

Okay, we jest. It was front page news the world over. Time flies, eh?


Well, now, 12 months on, we decided to catch up with the brains behind the mission, Alan Stern, to see just what we’ve learned, what’s left to answer about Pluto, and what we can expect next from New Horizons. Alan, who is the principal investigator on the mission, first dreamed up the idea of sending a spacecraft to Pluto in 1989. Last year, that dream was realized.

Check out our interview with him below.

Hi Alan. What’s it been like to be involved with the New Horizons mission?

"For most people on the mission, they’d never been a part of anything like this. I’d never been on a 'first' mission before. I’d been on a flyby of an asteroid, been on missions to Mars. Most of us said we’d never be involved in something like this again."


What was it like when the first data came in?

"After the flyby, we started to download data, and all of a sudden it’s like you’re orbiting Pluto. Every week it’s raining spectra and data types of all kinds. And it’s still continuing. We’ve got all the way to October 'till we finish. In fact, we’ll be getting data after Rosetta’s over [in September], and we’ve been gone from Pluto for a year!"

One of the many stunning Pluto images from New Horizons. NASA/JHUAPL/SWRI

Have you been busy since the flyby?


"We’ve been writing papers like crazy. About 40 peer-reviewed papers, over 150 technical presentations, and close to 300 public talks. So, we’ve been busy [laughs]."

What’s been the most surprising scientific result?

"I would place two things at the very top of our scientific results. The most surprising is Pluto’s complexity. If you actually look at the number of land forms per million square kilometers, compared to other objects all around the Solar System, Pluto ranks by Earth and Mars, and everything else is just boring by comparison.

"Secondly, Pluto’s active on this massive scale geologically, 4 billion years after its formation. And that was not predicted or expected, and really has the geophysics-types scratching their heads how to explain it."


What had you expected to find at Pluto? Something akin to the dwarf planet Ceres, a gray and mostly barren world?

"We expected it to be much more interesting than Ceres. I don’t think many people on the science team at all expected Ceres, a typical gotta-be-a-planetary-scientist to love it [world]. 'Ooh, there’s a white dot!' [laughs]. The nearest analog we had before the flyby was a former Kuiper Belt planet called Triton, that is now captured into orbit around Neptune. But this is not Triton, this is like Triton on massive illegal steroids."

Has the public interest waned since the flyby?

"It’s been continual. Why are you sitting here? I probably get half a dozen interview requests every week, and I’ve had offers from people to write my autobiography. That just doesn’t normally happen when you’re on a space mission.


"The actual flyby was off the scales, NASA had never had anything like it. A billion web hits in one day. 458 newspaper front pages on all seven continents, including Antarctica. I know this by the way because I gave a public talk that was put on YouTube, in which I said “on every continent except Antartica.” And then I got an email from a guy who runs the one and only newspaper in Antartica, and he said “bullsh*t!”, with a picture of his cover."

Could there be another mission to Pluto after New Horizons?

"Yeah. I mean, we’re thinking about it. It’s 1989 again, we’re at the very earliest stages."

New Horizons revealed a layer of haze on Pluto. NASA/SWRI


What sort of proposals are there?

"There are many ideas floating around. There are ideas for orbiters, several that have been mentioned or studied, since New Horizons. There’s a concept that I really like, but that’s very unlikely to succeed, to fly a whole series of very small spacecraft by Pluto, CubeSats.

"There’s [also] a concept I invented called a hyper orbiter, which is actually a very high velocity impactor that survives on the big moon Charon, which is in orbit around Pluto. So you can get an orbiter by landing on Charon. This uses formerly classified military technology for doing reconnaissance from artillery shells that land behind enemy lines. So we get a Charon lander and a Pluto orbiter."

Is there any scope for private missions to the outer Solar System?


"Well, I’m certain that private exploration of the Solar System will come along. In May, you know, Elon Musk announced the first Dragon capsule to Mars. However, I don’t think there’s really a market for Pluto yet. But, well, you know, the 21st century is young."

What Pluto science is left to come from New Horizons?

"Four of the instruments still have data to report, and a fair amount of imaging. None of the close-up stuff, but after we passed Pluto, on the far side from the Sun, we did a lot of look-back imaging at just the sliver crescent of Pluto. We took hundreds of images like this, and we hope to be able to see details on the night side. We arranged the flyby to be when Charon was illuminating it with moonlight, so it’s not completely pitch dark. Charon is actually as bright as a full Moon on Earth. Our objective for that experiment is to look for frost on the night side.

"[We also] have massive data sets that are ring searches [as it is thought there may be a faint ring around Pluto]. It could be a lot of blind sky images, or it could be a big headline."


What’s New Horizons doing next?

"It’s going [to flyby a Kuiper Belt Object] in the next three years. But 2019 is not final. There’s some science before, and some after. We’ve been asked by NASA to use New Horizons as an astrophysical observatory out there in the Kuiper Belt. We might look for exoplanets beyond the clutter of our Solar System’s dust."

Pluto is still geologically active, but no one is sure why. NASA/SWRI

Is the spacecraft expected to stay operational to the edge of the Solar System?


"Yes. It’s powered to run probably longer than I do, 25 to 30 years from now."

And finally, what has been your single biggest highlight of the mission?

"My highlight, which is why I f*cking love science, was watching the New Horizons team [fulfill] a promise 15 years before to pull off exploration of the farthest worlds anyone had ever explored, and to do it flawlessly. Just to see the emotion on their faces, that was the highlight for me.

"To see it all go so well, and all those people knew this wasn’t pretend, this was what we worked on, some people since the '90s, that was unforgettable."


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