Q&A With ‘The Pluto Doctor’
New Horizons scientist Leslie Young discusses what to expect from the flyby on Tuesday, and the 28-year wait leading up to it
2015 marks The Year of Pluto. The New Horizons mission is accomplishing one more major planetary science goal: to fly by the last large body in our solar system. Some are calling Pluto the last frontier, a big win for space exploration.
The Pluto Doctor, or Dr. Leslie Young as she is more commonly known, is the deputy project scientist on the The New Horizons mission. Whether Pluto turns out to be a dwarf planet, planet, or icy body, Young knows a lot about the most famous underdog of our solar system. She is what you could call a Pluto aficionado. Having studied the “King of the Kuiper Belt” since the 80’s, she not only helped to discover Pluto’s atmosphere, but is part of the team that built a custom spacecraft with only one goal: to fly by the former planet.
New Horizons is just a few days away from completing a nine year journey to the edge of our solar system. Not much bigger than a baby grand piano, New Horizons has been traveling at incredibly high speeds and carries onboard a slew of instruments in order to give the scientists a full picture of what’s been going on in the outskirts of the solar system. In 2006, Pluto was demoted from planet to “dwarf planet”, and since then has been a point of contention, not only among scientists, but in the public as well. Young sat down with us to discuss what it’s like to have waited 28 years to finally arrive at Pluto, and how she earned the title of The Pluto Doctor.
You have been studying Pluto since 1987. What made you decide to dedicate your life to it?
I began studying Pluto before I even entered grad school. My parents told me my first job out of college was very important and I thought, “What do parents know”? Turns out my first job out of college was programming for professor Jim Elliot at MIT. I ended up being on the team that discovered that Pluto had an atmosphere and that changed my life. I went on to grad school with Jim Elliot, wrote my thesis on Pluto and have been studying it ever since. When you get to change all of the textbooks, that’s a really good feeling. You just want do it again.
What We May Find
Your official title for New Horizons is Deputy Project Scientist. Can you explain a little about your role in the mission?
One of my main jobs is planning the encounter sequence. A project scientist’s job is very cross-cutting. I basically need to explain the science to anyone who needs to hear it. Most of the time that’s to other engineers on the project. If one of the people on the imaging team says we want to take these really good pictures, we discuss how to design a spacecraft that can do that. There’s a lot of translation between scientists and engineers and the other way around.
So basically you need to understand all of the science, everything about the spacecraft and the entire mission?
Basically, yes. You have to know everything about the mission, the design of the spacecraft and of course, the target. It is more broad than deep. You also have to know who on your team to go to when you need the specific answer, and we have a really great team on New Horizons. I am grateful everyday for the scientists that I get to work with.
Upon its approach to Pluto, New Horizons will have travelled approximately 3 billion miles in 9 years. You and your team have been waiting a very long time to get to Pluto. What are you most excited about seeing as we get closer?
When you observe Pluto or any astronomical object with a telescope on the ground or around Earth like Hubble, you have to carefully place the pieces together. Sometimes it feels like you’re building a house of cards. You have to make deductions based on very tricky information and have to work really hard to get the answer. When we finally get to Pluto it will be like flipping to the back of the book to get the answers. Not only will it tell us what Pluto looks like and what processes are going on but it will help us understand what we’ve been doing for the last 40 years. Then when you go back to the telescope 10 years later and see that things have changed, we will know what we’re looking at.
We <3 Pluto
How important is it to study Pluto, especially given its relatively recent demotion?
Pluto has all of these cousins in the outer solar system. The moon of Neptune called Triton is very similar to Pluto. There are other large objects out there like Eris. If we understand what’s going on at Pluto, suddenly we can understand how a whole group of other objects in our solar system function, and maybe even in other solar systems.
Do you think we might learn anything that could potentially change Pluto’s status from dwarf planet back to planet? In your scientific opinion, is Pluto a planet or a dwarf planet? Should it be in the same class as other “dwarf planets” like Ceres?
I think the term “dwarf planet” is not a useful term and will end up dying a natural death. Whenever you go to a conference there is never a ‘dwarf planet’ question. When you submit a paper to a journal they don’t say “well, we have to find a dwarf planet expert”. I think categories should only be used as much as their useful. Sometimes it’s handy to clump Pluto in with Triton which is a moon, Eris which is another dwarf planet and some other of the larger Kuiper Belt objects, so what do you call those? Ice worlds? That’s what I like to call them.
What do you think is the most exciting discovery that could come from this mission?
I think the most exciting part of the mission is that it will make Pluto and Charon an accessible world. A world where you can have a picture in your mind of what it’s like. It takes an awful lot of imagination to speculate what Pluto or Charon might look like just from what you get from the telescope. However, something like a spacecraft mission is a gift to the world because suddenly you don’t have to spend 3 months pouring over something you got from the telescope to get a tiny bit of a clue. You can look at a picture, look at a map and instantly get a gut feel about what these worlds are like.
Pluto and Charon are in a binary orbit around one another. Can you talk a little about how this system works and what we might find out about Charon as we get closer?
One of the things that we’ve learned in the last few decades is that the solar system is a really violent place where things hit each other. The Earth-moon system probably came out of something Mars-sized hitting Earth. We think probably the Pluto-Charon system was some sort of impact. If we can figure out how the Pluto system formed it can tell us something about impacts. There are other Kuiper Belt objects that orbit each other instead of one orbiting around a mutual barycenter between them, so Pluto is not completely unique in that regard. We’ve often flown past the planets and been delighted by its moons. The moon Titan around Saturn has got water running down, methane running down, almost Earth-like weather systems. I expect that Charon is going to amaze us. All this time we’ve been thinking of it as this dull counterpart to a more dynamic and exciting Pluto, but I think it’s going to end up knocking our socks off.
Because Pluto is approximately 3 billion miles from Earth, how long will it take for your team to receive data once New Horizons sends it?
It will take 16 months to get all of the information back from New Horizons. The downlink time from the spacecraft is 4.5 hours meaning that the data going the speed of light will take 4.5 hours to reach us. Pluto is very far away. So to communicate with the spacecraft we are looking at a 9 hour round trip.
We have already seen images from New Horizons that are better than what we had seen from the Hubble space telescope. What do you think those surface features might be?
When we launched New Horizons we already knew a couple of things; one is that Pluto is one of the most contrasty places in the solar system. It has some of the darkest places and some of the brightest places and that’s even from the blurry images from Hubble. We knew that the geology was going to be something spectacular and that’s what we’re starting to see with these first images, very bright areas and very dark areas. The other lesson we learned was from Voyager–it flew past Pluto’s cousin, Triton, in 1989. The two Voyagers were amazing spacecrafts that really opened up the outer solar system for scientists and for the public. But, it did not fly an infrared spectrometer and if you want to know what surfaces are made out of you need an infrared spectrometer, so we are flying RALPH to Pluto and its moons. We even tailored it to tell us what the surface ices on Pluto were made out of.
The cameras on board, RALPH and LORRI, are supposed to give us very high resolution images. How detailed will the images be from the closest approach?
On our flyby day we will be taking compositional maps with geologically interesting resolutions so we will be able to look and say: here’s a crater, there’s a mesa and here is how the top of the mesa is different from the side of the mesa. It’s going to be fantastic. It will be like flying over the Earth and being able to make out the features of the New York City skyline.
“I think Charon is going to end up knocking our socks off.”
What, if anything, can studying Pluto teach us about Earth and the formation of the solar system?
I think that understanding the 3rd zone (everything past Neptune) is important to understanding the basic architecture of our solar system and maybe other solar systems. It looks like there might be Kuiper Belts around other stars too. We think that Earth might have been influenced by comet impacts which came from the same area that Pluto came from. The chemistry in Pluto’s atmosphere might tell us something about the chemistry of the early Earth. There’s definitely a lot to be learned.
What’s next for New Horizons after the Pluto flyby? Will it venture out past the solar system like Voyager 1 or will it be visiting any other bodies in the Kuiper Belt?
We are doing a flyby for two reasons. The first reason is, if we wanted to slow down we would have to take so much fuel it would take us decades and decades to get there, by that time Pluto would be father from the sun and there would be less surface illuminated, it’s just not a good idea. And the other reason to do a flyby is because once we pass Pluto we can go on to another Kuiper Belt object. That’s our intention. Nothing is guaranteed but we hope to continue to explore the outer solar system after Pluto. After the mission is over, New Horizons will eventually leave the solar system as Voyager did before it. We’ve been looking at the space between the planets as we’ve been going out, as we go out we will be studying the dust in space so we will continue to measure dust and even when we’re done with the flyby, there are things that we can do in situ and can ask, what is the spot that I am in right now like? We plan to keep doing that as we go further and further out.
“Pluto is one of the most contrasty places in the solar system.”
New Horizons also happens to be the fastest thing ever launched from Earth. How fast is it going?
New Horizons launched on a very big rocket and is approaching Pluto at 35,000 mph. Voyager 1 got 4 slingshots to speed it up: Jupiter, Saturn, Uranus and Neptune. New Horizons got one slingshot from Jupiter so right now it is going very fast. We got past the moon in 9 hours. The Apollo mission took 3 days to get to the Moon. Think about what the Galileo spacecraft had to do to get to Jupiter, it took 6 years for it to reach Jupiter, New Horizons got there in 13 months! It was a very small spacecraft on a very big rocket.
You’ve been patiently waiting for 28 years to arrive at Pluto. Where will you be when the flyby takes place?
I will be at the Johns Hopkins Applied Physics Lab in Maryland. Because we’re not going to be getting a lot of data down on the first day of closest approach it lets us spend that day celebrating the arrival.
The flyby is July 14th, but we wont receive any images until July 15th. Why is that?
We will get one image that is taken right before closest approach around 12 hours before. It will be a nice shot of Pluto filling a single frame of our imager LORRI. Our choices were that we could either point the spacecraft so that it could take pictures or point it so that it could talk to Earth, so we’re going to do a little bit of talking to Earth so that we can get the official: I’m OK! and then because we only fly past Pluto once we chose to spend our flyby time taking pictures.
Do you think we’ll ever go back to Pluto?
I think we’ll go at least twice. How can you visit someplace only once?