New Horizons - Are we there yet?

The New Horizons spacecraft has been on its way to Pluto for almost ten years - and on July 14, 2015 it will be at its closest to the “icy dwarf”. While we wait, EAPS alum Cathy Olkin ’88(XVI), PhD ’96(XII), Deputy Project Scientist and Team Leader for the PI on New Horizons, talks about the mission and its deep connections to EAPS. Cathy’s mentor, EAPS Professor Jim Elliot (1943-2011) was the pioneer of the stellar occultation technique that led to the discovery of Uranus’ rings and Pluto’s atmosphere, and current EAPS Professor Rick Binzel is a Co-Investigator on the New Horizons Team.

EAPSpeaks: What excites you most about New Horizons?

Olkin: What excites me most is being one of the first people to get a close up look at this new realm of the solar system - somewhere we've never seen before. The New Horizons Pluto encounter will be the first time we have seen a Kuiper Belt object (KBO) close up. The Kuiper Belt is a completely different planetary regime from anything we have visited before - not the terrestrial planets, nor the gas giants we have become familiar with, but this great ring of hundreds of thousands of rocky and icy bodies out on the edge of our solar system: a great million year old debris field, the remnants from when our solar system formed. It can’t help but be a revelation to see this new class of bodies close up.

When I was an undergraduate at MIT in the 1980's, we didn't even understand that there were objects in the Kuiper Belt - people had postulated that maybe there was something out there but that wasn't confirmed until the discovery of the first KBO (after Pluto) in 1992. 

Of course, Pluto, discovered in 1930 by American astronomer Clyde Tombaugh, famously was, for most of the 21st century, considered to be the solar system's 9th planet (if a slightly oddball one). It was only in 2006, with New Horizons already many millions of miles into its journey, that it was formally reclassified as a dwarf planet, but I still consider Pluto a planet and refer to it that way. So I have been the witness of a transformation of our understanding of the structure of the solar system just since the time I was in college. 

EAPSpeaks: What discoveries are you most eagerly anticipating?

Olkin: New Horizons has a really capable payload - we've got seven instruments on board that can look from the ultraviolet to the near infrared and also, using radio science, to investigate the atmosphere. We'll be looking at Pluto with everything we've got and, while I don't know what we're going to find, I, for one, am very excited to learn more about its atmosphere. While Earth based stellar occultation measurements have allowed us to look at the pressure and temperature of the atmosphere as a function of altitude, we simply can't see the lowest levels of Pluto's atmosphere from Earth. With New Horizons, we'll be able to probe those lower levels with the on-board radio science experiments.

My EAPS advisor, Jim Elliot, was the first person to definitively observe that Pluto has an atmosphere. We used the same stellar occultation technique when I was in graduate school to look at the atmosphere of one of Neptune’s moons, Triton. At that time, we also tried to look at Pluto but Pluto wasn't cooperating so we weren't successful until the stellar occultation in 2002, work that ultimately indicated Pluto’s atmosphere was expanding. 

EAPSpeaks: How did your training in EAPS prepare you for this mission?

Olkin: Foremost, my training in EAPS gave me a rock solid foundation in scientific investigation. I was an engineer prior to coming to EAPS as a graduate student (my undergraduate degree, also at MIT, was in aeronautical engineering, and I had spent some time working at the Jet Propulsion Laboratory) - of course I had science classes but what I learned about being a scientist I learned in Course XII. I also learned so many lessons from Jim as well as my fellow graduate students, among them Leslie and Elliot Young, Amanda Bosh and Mike Person.

A particularly valuable lesson I learned was, when you have time on a telescope, you can't waste it, especially when making occultation observations where timing is so critical. It's not enough to simply be at the right place at the right time, although that can be tough in and of itself: You have to be ready to dependably take data. There was obviously very little you could do about clouds (apart from go fly on the Kuiper Airborne Observatory, KAO) but certainly you did not want to miss an opportunity simply because you weren't prepared. I think that's a huge lesson for working on a spacecraft mission. We build very carefully designed sequences of observations to collect the data to answer the scientific questions we are interested in. We develop contingency procedures. We do lots of checks and validation on the sequences, and I believe that comes naturally to me because of how I learned to be an observer in Course XII.

EAPSpeaks: Is there still a place for the small hands-on observing experience you get at the Wallace Observatory?

Olkin: I was a teaching assistant (TA) for the observing class for a number of years, so I was at Wallace often. I would say it's even more important now than it used to be because we need to train the next generation of observers with hands on experience. A lot of times these days you're observing remotely, which is excellent, and I love having the opportunity to do that, but in order to learn the craft nothing replaces physically being there. So I really believe Wallace has an extremely important place in education, and in science.

EAPSpeaks: What are your best memories of EAPS?

Olkin: I loved being a TA. I loved working with the students, and teaching them, and the excitement when they were able to put it together and understand what was being taught in the classroom and connect that to what they were actually doing at Wallace. The observing class is an excellent class because it teaches so many things and that made it very exciting to TA. Besides that I really enjoyed the camaraderie of the graduate students. Sharing ideas, working together, the spirit of the group was just really great.

EAPSpeaks: What comes after Pluto?

Olkin: Well one thing that's really interesting about the Pluto mission is that it's going to take a while to downlink all the data. The New Horizons spacecraft is very far away from the Earth. At closest approach, we'll be 32 times the distance between the Sun and the Earth away. At that distance it will take ~ 4.5 hours for data to travel from Pluto back to us. In addition, because we wanted to get to Pluto in a reasonable amount of time, we had to have a small but highly efficient spacecraft, however that meant our downlink rates are pretty slow - about 1000 bits per second. For comparison, at that rate the HD version of the new Mad Max movie would take about 555 days to download. For this reason it is going to take until late 2016 to recover all the data, longer still to analyze it. This makes it a little bit different from most earlier missions. Come mid-July we'll be having press conferences, we'll be talking about what we're learning, but more than likely there will still be mysteries up on the spacecraft, things that haven't been sent back to the ground yet, that we won't know about until months later.

Beyond the Pluto encounter, using the Hubble telescope, we have identified two other potential KBOs that we could fly by - one or the other, not both - and so once we have passed Pluto we will write an extended mission proposal to NASA which, if approved, will see New Horizons flying by a second target in approximately 2019. This is not a given, but we are extremely hopeful this post-Pluto mission will be funded. New Horizons historic near-decade long journey has put it on the Kuiper Belt's doorstep. How can we not now carry on, paraphrasing those by now immortal words, to boldly go where no one has gone before? After all this is just our solar system: rumor has it there are quite a number more out there waiting for us to explore!

Meet EAPS alumna Cathy Olkin ’88(XVI), PhD ’96(XII, XIID)

EAPS alumna Cathy Olkin is a planetary scientist with interests in icy outer solar system worlds. Using near-infrared and infrared spectroscopy she studies icy surfaces and stellar occultations to investigate tenuous atmospheres. She is also interested in spacecraft investigations of these worlds and is a member of the New Horizons team which will provide the first close-up look at Pluto.

Olkin began her career in engineering, getting her undergraduate and masters degrees at MIT in Course XVI (Aero-Astro). After working at NASA's Jet Propulsion Laboratory, she returned to MIT for graduate school where, working with EAPS advisor Jim Elliot, she obtained a doctorate in planetary science for her work involving stellar occultation studies of he atmosphere of Triton. 

Image captions: Upper right - Cathy pictured with a large telescope in Tasmania; left - Cathy during hypnoxia training - images courtesy C. Olkin.