In the nine years that NASA’s New Horizons spacecraft has spent zooming toward Pluto, most of the seven instruments aboard the piano-size probe have been in hibernation, waiting for their chance to plumb the mysteries of our solar system. One, however, has been collecting and pinging back data all this time, a tireless worker with a taste for dust.
The instrument, known as the Venetia Burney Student Dust Counter, was created at the University of Colorado, Boulder, by a small group of students in physics, mechanical engineering, aeronautics and astrophysical sciences. At the time of launch, it was the only student-led instrument on any interplanetary mission, and it has gone farther from Earth than any other. Its purpose aboard New Horizons is to measure the amount and density of space dust encountered on the journey to the dwarf planet, analyzing the remnants of colliding objects like asteroids, comets and expired planets. With this information, scientists will be able to understand more about activity in the Kuiper Belt, a ring of icy debris just beyond the orbit of Neptune.
The instrument was first proposed by Mihaly Horanyi, a physics professor at the university, as part of the school’s pitch to NASA to piggyback on a mission to Pluto. While the university’s Laboratory for Atmospheric and Space Physics, where Dr. Horanyi is a research associate, was not chosen to lead the mission, New Horizons’ eventual principal investigator, Alan Stern, from the Southwest Research Institute , wanted a dust instrument on the spacecraft. So Dr. Horanyi put in a second proposal, this time for an instrument built and run entirely by students, and in 2003 NASA approved the Student Dust Counter.
“There is a strong scientific rationale to have a dust instrument onboard,” Dr. Horanyi said. “Dust measurements beyond Pluto will give estimates on the density and size distributions of the Kuiper Belt objects. These measurements are critical to compare our own dust disk — the Zodiacal dust cloud — to the dust disks observed around many other stars.”
The project started with three students Dr. Horanyi had recruited from his own faculty. Soon, word spread around campus that a professor was looking for students to work on a NASA-led mission to Pluto. “In a matter of months, we had 20 or so students on the team,” Dr. Horanyi said. Though it was an academic project, the Student Dust Counter had to adhere to the same NASA standards as the other instruments on New Horizons, which meant regular reviews in front of panels of visiting NASA engineers. (Dr. Horanyi remembers it more as an “interrogation.”) In the two years it took to build the dust counter, many students graduated and moved on, replaced by a new batch of undergraduates. Of the original team, four students are still at the University of Colorado, Boulder, in some capacity; two graduated, but eventually returned to work on the Student Dust Counter.
Tiffany Finley came onboard as the project manager in 2002, while she was a graduate student. She was responsible for seeing the instrument all the way through, from design to construction to calibration. “I’d just been looking for something cool to work on, and suddenly it was like, wait, you guys are going to Pluto? Sign me up,” she said. After graduating, Ms. Finley worked as an aerospace engineer before landing a job at the Southwest Research Institute, first with the NASA Juno mission to Jupiter and then with New Horizons. She is now responsible for command sequencing on the Student Dust Counter — creating a series of orders that tell the instrument what to do and when to do it. (Dr. Horanyi joked that Ms. Finley started out as his student and is now his boss.)
Similarly, David James began work on the dust counter in 2003 for his physics Ph.D., with Dr. Horanyi as his adviser. His work looked at the polyvinylidene fluoride detectors that make up the dust counter, which generate a charge when hit with a dust particle. The detectors are composed of a plastic film and coated with a thin layer of metal; when a dust particle hits the detectors, the charges rearrange themselves, creating an electronic signal. The Student Dust Counter measures this signal and sends the information back to Earth for analysis.
Dr. James, too, left the university for a few years after graduating, but returned after realizing that the dust counter was a unique opportunity. “New Horizons is one of the greatest missions in space history,” Dr. James said. “To continue to be part of that, especially on a project you started working on as a student, is too exciting to pass up.” Dr. James is now overseeing the latest batch of Colorado students recruited to work with the instrument as New Horizons gears up for its flyby of Pluto in July.
Dr. James and Ms. Finley have fond memories of summers spent in the lab working on the dust counter, despite the sleepless nights spent worrying about the NASA review panels. Dr. James recalls one long week testing the instrument in various temperatures to make sure it could survive the journey to Pluto. The students worked in 24-hour shifts, juggling classes and other obligations, to document the procedure.
“We were driven by the knowledge that if our little instrument broke while up in space, it would damage the entire craft and put the whole mission in jeopardy,” Dr. James said. “We were solving problems students aren’t normally required to solve, and that proved to be invaluable experience.”
Dr. Horanyi and his team have been steadily collecting data from the Student Dust Counter during its nine-year trip, publishing a number of research papers. However, the dust counter’s big moment is yet to come. After the Pluto flyby, New Horizons is scheduled to keep flying away from the sun, with enough power to continue comfortably for another 20 to 25 years, exploring unfamiliar parts of the solar system.
“If you were an alien world looking into our solar system and saw all the dust, what you’d really be looking at is the footprints of our planets,” Dr. James said. “Similarly, if we look at other solar systems, we can do the same. That’s why these tiny particles of dust are so important. They can tell us what used to be there.”
Last year, Dr. Stern at the Southwest Research Institute organized a reunion for the 30 or so students who had worked on the Student Dust Counter. For Dr. Horanyi, it was an emotional moment.
“That’s 14 years’ worth of people on the same project,” he said. “To see that so many people still care deeply about it was an incredible thing to witness.”
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