{"id":7,"date":"2019-05-09T09:49:29","date_gmt":"2019-05-09T16:49:29","guid":{"rendered":"https:\/\/magazine.hmc.edu\/spring-2019\/?p=7"},"modified":"2020-04-01T15:15:15","modified_gmt":"2020-04-01T22:15:15","slug":"beyond-the-horizon","status":"publish","type":"post","link":"https:\/\/magazine.hmc.edu\/spring-2019\/beyond-the-horizon\/","title":{"rendered":"Beyond the Horizon"},"content":{"rendered":"

Four billon miles from earth<\/strong>, a massive region of planetesimal bodies called the Kuiper Belt circumscribes our solar system. Home to dwarf planets like Pluto, the belt also boasts thousands of small, planet-like objects which may date back to the beginnings of our own planetary system.<\/p>\n

On Jan. 1, 2019, NASA\u2019s New Horizons space probe completed a flyby of one of these objects\u2014 (486958) 2014 MU69, informally known as either MU69 or Ultima Thule. More than three years earlier, New Horizons had become the first spacecraft to investigate Pluto. Back home on Earth, six Harvey Mudd alumni who had made a small contribution to this historic moment in space exploration looked on.<\/p>\n

\"Ultima
The most detailed images of Ultima Thule obtained just minutes before the New Horizons\u2019 closest approach at 12:33 a.m. EST on Jan. 1.<\/figcaption><\/figure>\n

New Frontiers<\/h2>\n

Nearly a decade before New Horizons reached Ultima Thule, Steven Berry \u201911 Austin Lee \u201910, Cullen McMahon \u201911, Claire Robinson \u201911, Chris Sauro \u201910 and Florian Scheulen \u201910 were recruited for a Clinic Program project with the Southwest Research Institute (SwRI), a science, engineering and technology nonprofit that helped engineer the New Horizons spacecraft alongside the Johns Hopkins University Applied Physics Laboratory.<\/p>\n

In 2009, the students were charged by SwRI staff scientist and clinic liaison Marc Buie with improving an optimal image subtraction (OIS) algorithm. This algorithm would be used to detect and track Kuiper Belt objects, with the goal of selecting one for New Horizons to study in the future.<\/p>\n

\u201cThose folks\u2014they were really, really clever, crafty students. They dug in and tackled the project and did everything that I asked them to do and more. It was fantastic,\u201d says Buie, for whom space exploration has always been a calling.<\/p>\n

\u201cAt an age when most kids would say they wanted to be a doctor or a fireman or something like that, I would actually say I want to be a nuclear physicist, not really knowing what that meant,\u201d he recalls. \u201cI got really turned on to the space program, watching the astronauts go to the moon, and that set me on a course for where I\u2019ve ended up today.\u201d<\/p>\n

As for his planet of choice: \u201cI distinctly remember Pluto picking me,\u201d he adds.<\/p>\n

In fall 1982, Buie was about to embark on his doctoral dissertation in planetary sciences at the University of Arizona. After reading a paper his adviser had written about methane on Pluto, he became hooked on all things Plutonian. Buie\u2019s dissertation went on to prove that this methane was on the planet\u2019s surface rather than in its atmosphere\u2014a big change in how scientists viewed Pluto at the time.<\/p>\n

Even then, a mission to the edge of the solar system beckoned.<\/p>\n

\u201cI remember thinking: We\u2019ve not gone to Pluto with a spacecraft, but this is something that could happen in my lifetime, during my career, and I want to be a part of that,\u201d Buie says.<\/p>\n

From then on, he and other Pluto enthusiasts devoted their energies to lobbying for a funded mission. Finally, in 2006, New Horizons launched from Cape Canaveral. Its destination: Pluto and beyond.<\/p>\n

In the Stars<\/h2>\n

Pluto looms large in Buie\u2019s life. But for the six Mudders, it was new territory.<\/p>\n

According to Lee, who has since gone on to work for Apple as a silicon engineer, \u201cour biggest challenge at first was just getting up to speed; we had a lot to learn.\u201d<\/p>\n

After setting up the project, Buie travelled to campus to meet with Lee and his classmates.<\/p>\n

\u201cMarc was fantastic,\u201d says McMahon, now CEO of Bay Area simulation infrastructure company Simr. \u201cHe brought a clear focus to the work he wanted out of us and demonstrated with his hustle and engagement what he expected of us on the project.\u201d<\/p>\n

His expectations were high: the group was asked to speed up the OIS algorithm by a factor of at least a thousand. Originally written in C, the algorithm had been converted to IDL (interactive data language, a programming language commonly used by planetary scientists) by someone who was not well-versed in IDL. As a result, it was glacially slow.<\/p>\n

\u201cWhile it worked, it took hours to do one image subtraction, and only on a small test image at that,\u201d Buie remembers. \u201cI knew that there was a useful tool here, but I needed help in just turning the crank and turning it into a tool that I could actually use.\u201d<\/p>\n

The New Horizons team planned to use OIS to search images from ground- and space-based telescopes for a Kuiper Belt object that would become the spacecraft\u2019s post-Pluto target.<\/p>\n

How? Imagine using a powerful telescope to take multiple images of the star-filled Milky Way. Using OIS, you can \u201coverlay\u201d those images on top of one another and \u201csubtract\u201d all the stationary objects. This is how you find \u201cobjects marching across the field. That\u2019s how you discover planets. That\u2019s how Pluto was discovered,\u201d explains Buie.<\/p>\n

After an in-person IDL bootcamp, Buie set the undergraduates to work. There was a lot of experimentation at first, according to Lee.<\/p>\n

\u201cI remember spending a few late nights immersed in low-level optimizations, either trying to wrap my head around how to rewrite nested loops in IDL\u2019s paradigm, where array arithmetic is preferred, or porting the most critical routines to C.\u201d<\/p>\n

McMahon, who had already been doing research into image processing, found that \u201cgetting the pipeline of data processing moving was difficult. But it was really cool to see once it started.\u201d<\/p>\n

The team eventually got the OIS running like clockwork. Then, they set about creating a brand-new tool to solve another issue with telescopic imaging.<\/p>\n

Just as a wide-angle camera lens can distort a photograph, \u201cthe same thing happens on a much smaller scale with a telescope,\u201d Buie explains. \u201cIn order to line up the images and do optimal image subtraction, we needed a tool that allowed us to map and resample an image from one coordinate system to another.\u201d<\/p>\n

The resulting tool, christened Dewarp, was a resounding success.<\/p>\n

\u201cYou could take some crazy distorted image, describe how it\u2019s warped and then straighten it up and make a nice rectilinear version,\u201d Buie says. \u201cThis was a tricky programming effort in and of itself\u2014 you actually had to know IDL really, really well for this to run fast and get the job done.\u201d<\/p>\n

\"Diagram
The Kuiper Belt is one of the largest structures in our solar system\u2014others being the Oort Cloud, the heliosphere and the magnetosphere of Jupiter. Its overall shape is like a puffed-up disk, or donut. Its inner edge begins at the orbit of Neptune, at about 30 AU from the Sun. (1 AU, or astronomical unit, is the distance from Earth to the Sun.)<\/figcaption><\/figure>\n

Going Interstellar<\/h2>\n

It will take nearly two years for all the data from the Ultima Thule flyby to reach Earth. For the Pluto encounter, those data were home in 15 months. What are New Horizons\u2019 most interesting discoveries so far?<\/p>\n

Surprisingly, Pluto and its moon Charon have large, canyon-like features. These are most likely the result of subsurface oceans freezing and thawing, making the planet\u2019s crust expand.<\/p>\n

\u201cNone of us really expected to see that, because we expected [any oceans] to have frozen out a long time ago.\u201d<\/p>\n

Another finding that may rewrite the textbooks is what appears to be a volcano located on an ice-covered basin called Sputnik Planitia, a relatively young feature on Pluto\u2019s surface.<\/p>\n

\u201cA volcano is not necessarily a crazy thing to think about being on a planetary body,\u201d Buie explains. However, this one appears to be active, suggesting that \u201cthe heat and the energy that was captured at the time of [Pluto\u2019s] formation took a lot longer to dissipate than we were originally expecting. It is mind-blowing that something that small and cold could still be active today.\u201d<\/p>\n

Almost 10 years after the clinic project, Buie still uses OIS and Dewarp almost every day. While the OIS application was part of the process of finding and selecting Ultima Thule, both were \u201ccentral to the work that I did to help make the mission a success. Having these things in my toolkit just made it all possible.\u201d<\/p>\n

And what about the alumni?<\/p>\n

\u201cIt gave me a lot of respect for the scale of the work that leads to modern discoveries,\u201d says Lee, who has been eagerly watching the most recent updates on Ultima Thule.<\/p>\n

\u201cThe follow-up data are astonishing,\u201d he says. \u201cIf this is what we have to discover in what was previously a mere pixel on our best telescopes, what other surprises are out there?\u201d<\/p>\n

McMahon saw the flyby news on New Year\u2019s Day.<\/p>\n

\u201cI thought it was incredible that our work finally had an impact almost a decade later,\u201d he says. \u201cI\u2019m extremely proud that we were able help, though the lion\u2019s share definitely belongs to Marc.\u201d<\/p>\n

Buie, who himself worked in a research lab as an undergraduate, understands the significance of student involvement in new discoveries.<\/p>\n

\u201cI know just how valuable and how important it is to be involved with research and researchers and to get your hands dirty with this kind of stuff,\u201d he says.<\/p>\n

New Horizons has now left Ultima Thule to travel through the remainder of the Kuiper Belt and beyond, making it only the fifth space probe to leave our solar system. The plutonium running the craft should last at least another 20 years, allowing us a glimpse into the workings of interstellar space.<\/p>\n

The Clinic group\u2019s work has already proven invaluable to New Horizons\u2019 exploration of the farthest reaches of our planetary system.<\/p>\n

\u201cWhat I see looking at these images is going to rewrite the book on our understanding of how the solar system was formed,\u201d Buie says. \u201cIt\u2019s that important. It\u2019s that powerful. And it\u2019s great that we got to involve this Clinic team from Harvey Mudd\u2014it takes so many people to make these kinds of fundamental discoveries.\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

Four billon miles from earth, a massive region of planetesimal bodies called the Kuiper Belt circumscribes our solar system. Home […]<\/p>\n","protected":false},"author":1,"featured_media":77,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[2],"tags":[],"class_list":["post-7","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-features"],"acf":[],"_links":{"self":[{"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/posts\/7","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/comments?post=7"}],"version-history":[{"count":0,"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/posts\/7\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/media\/77"}],"wp:attachment":[{"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/media?parent=7"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/categories?post=7"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/magazine.hmc.edu\/spring-2019\/wp-json\/wp\/v2\/tags?post=7"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}