Thushara Perera and his students are hard at work building a device designed to better
grasp how cosmic dust gave rise to planetary systems and perhaps to life itself.
Story by KIM HILL Lab photos by MARC FEATHERLY
When Fiona Breyer ’17 and Lunjun (Simon) Liu ’17 were teenagers looking at the night
sky from their homes on two different continents, astrophysics seemed so exotic and
exciting. So the students were a bit nonplussed when their in-the-trenches experiences in astrophysics
began not by looking up, but by drilling down — learning to use a milling machine,
lathe, drill press, and other vital but rather unsexy pieces of equipment in the machine
shops in the Center for Natural Science basement.
The two are among a half-dozen students contributing to a project led by Associate
Professor of Physics Thushara Perera to design instrumentation that will help scientists
learn more about cosmic dust. Once regarded as a nuisance by astronomers because it
absorbs the visible light from objects, cosmic dust is now recognized for the role
it plays in the evolution of galaxies, stars, and planetary systems. Though not yet
fully understood, cosmic dust is also thought to have an integral role in the chemical
activity giving rise to complex molecules, some of which may be the precursors of
amino acids, the building blocks of life.
Perera realized there is no one facility in the world dedicated solely to the study
of cosmic dust candidates, or man-made items mimicking the dust’s chemical and physical
properties. At large research facilities, an apparatus is rigged together for testing
such candidates and then taken apart for other uses, says Perera, leading to systematic
Perera reasoned that a dedicated system for studying cosmic dust — one that utilized
the principles of observational cosmology — would greatly reduce such errors. “The
whole goal of observational cosmology is to reduce systematic errors when you are
looking at the sky,” he adds. “So our system is built from a different perspective.”
The National Science Foundation (NSF) recognized the novelty of this approach and
awarded Perera a grant for the project. At the project’s center is a spectrometer. Its basic function is to take in light,
break it into its spectral components, send those components through cosmic dust samples,
record the amount of light transmitted through each sample as a function of wavelength,
and display the data through a computer program.
Among the instruments Perera and his students are building is a Fourier Transform
Spectrometer (FTS), which makes use of an innovative concept put forth by Dale Fixsen,
a research scientist with NASA’s Goddard Space Flight Center. “I exchanged about three
emails with Fixsen and we did the rest,” Perera says. When they are finished, Perera
and his students will have constructed the world’s smallest FTS.
What’s most unique about the project is the design — the compact FTS is coupled to
a cryostat. Essentially a very cold refrigerator (referred to in the lab as “the fridge”),
the cryostat can cool samples to 4 Kelvin, or –452 degrees Fahrenheit. The fridge
can be used to match the temperatures of actual astronomical dust clouds (10-50 Kelvin).
The structure that holds the fridge, along with the pumping/vacuum station, were mostly
built and installed by IWU physics students. So were most of the thermometers, associated
cables and electronics, as well as special insulation within the fridge, which also
includes a bolometer, or millimeter-wavelength light detector. This sensitive instrument
measures radiant energy.
While Perera led the way in devising the spectrometer — from working out the mathematical
formula to writing the source code to cut metal for the ellipsoidal mirrors inside
the spectrometer —his students made major contributions. Showing these components
to a visitor, the professor ticks off some of the many advances made by past and current
Kyle O’Shea ’16 took Perera’s CAD designs for the FTS and machined most of the necessary
parts to high precision using IWU’s milling machine. He also implemented a system
to control the FTS’s moving mirror, and used Wesleyan’s 3D printers to make several
items, including an adapter for the vacuum enclosure of the FTS. O’Shea is now a Ph.D.
student in mechanical engineering at Michigan State University, where he’s working
on new technology for 3D printing.
Hansheng (Jason) Chen ’17 designed a robust optical window for the cryostat, so that
a wide spectral range of light can pass into the fridge without compromising the vacuum
within. After completing the design — which was fabricated at the University of Illinois
— Chen made changes and machined additional parts to help install the optical window.
This fall, he will enter a graduate program in theoretical astrophysics at the University
of California, Davis.
Huy Do ’16 — now completing his 3:2 dual degree in electrical engineering at Washington
University in St. Louis— was an early contributor to the project. Do’s work on the bolometer electronics and filter wheel mechanics
built a foundation for the progress that has been made on the instrument thus far.
As the project’s lead student this past year, Lunjun Liu played a major role in developing
and testing a unique filter wheel housed in the fridge. This wheel holds and switches
dust samples, allowing researchers to study up to eight different samples in one cooldown.
Liu machined shafts, pulleys, and dozens of other mechanical parts in the CNS machine
Liu’s first challenge was to learn basic skills and safety protocols needed to work
with these tools. “I had no experience in any kind of building before coming to IWU,”
said Liu, a native of Wuhan, China. “I was not expecting that would be something that
would be necessary for an astrophysicist.” But as he built the part, tested it, refined
it, and tested it again in a seemingly endless process, he began to grasp the importance
of such routine tasks to the final outcome.
Liu believes his “in-the-trenches” experience in the IWU lab has given him an important
advantage. Last summer he was selected for Caltech’s competitive Summer Undergraduate
Research Fellowship. Because he was familiar with cryostats, detectors and electronics
from his work at Illinois Wesleyan, Liu entered the Caltech lab confident of his abilities.
“At Caltech I observed other students not fully understanding the inner workings of
the equipment, because they are not building things step by step, without understanding
every concept of every device,” says Liu, who is returning to Caltech for a year to
assist with deployment of one of his projects there before entering graduate school
in astronomy at the University of Illinois. “I was able to provide my point of view
to fine-tune a device, for example, to provide a better outcome.”
Sharing with the World
“At temperatures this cold, so much can go wrong,” says Ronan Dorsey ’18, who joined
Perera’s lab group in May 2016 and worked through the summer, spending much of that
time machining parts for a “light pipe” within the cryostat that carries light from
the outside to the dust samples inside the fridge.
“The machining can seem menial,” Dorsey admits, “but it’s so important to take your time and just do it slow so you get it right.
Or, at least, as much as you can before you test it. And then you go back to the machine
shop when you figure out you did it wrong.” Breyer’s introduction to the project was equally unglamorous. When she joined as a
sophomore, she said her tasks involved screwing parts that had already been machined
onto the body, or applying oil to keep the machining functioning smoothly. “I had
no idea what I was doing at first,” she admits with a laugh. “It takes a while to
really understand the project.”
Soon, however, Perera tasked Breyer with automating logging of the fridge’s temperature
and detector data with LabVIEW, a graphical language used for data acquisition and
instrument control. In the summer of 2015, Breyer worked in Perera’s lab to collect
data as the spectrometer was being calibrated.
“My program would take data points every minute for something like 15 hours, store
it, and then we’d review it the next morning,” she says. According to Perera, Breyer
also played a large role in structuring and organizing the inside of the cryostat.
Breyer believes this lab research experience helped her secure a spot for a nationally
competitive NSF Research Experiences for Undergraduates internship in 2016.
“Going into the summer research experience at the University of Wisconsin–Madison,
I felt so much more confident about my abilities,” Breyer notes.
“Dr. Perera has always believed in me, even when I didn’t believe in myself, and he’s
made me feel confident in my abilities to do lab work, to be a physicist, and to be
The chance to work alongside a faculty member, building a device from the ground up
in hopes of learning more about the origins of planetary systems, is not lost on the
“Spending four or five hours a day for a whole summer with Dr. Perera, working one-on-one
on this project, is not something I would find at a big university,” Dorsey observes.
“Working directly with a physicist of Dr. Perera’s caliber has been the most rewarding
thing about this entire project.”
Dorsey has become the ‘go-to-guy’ in daily operations as Perera and his group have
conducted three cooldowns in order to improve the bolometer’s performance. After a
successful cooldown of the cryostat in February, the next step is to test and troubleshoot
the entire system. Construction is scheduled for completion this summer, when the
NSF grant’s funding cycle comes to a close.
Perera said that to his knowledge, there has been no other successful operation of
a detector of this kind using a ‘dry’ cooling mechanism that employs gas pulses, rather
than liquid helium, to cool. The only other FTS Perera knows of that’s remotely similar
to the one at Illinois Wesleyan is housed in the lab of a colleague at the University
Despite the daily challenges and troubleshooting necessary to get a new instrument
of such complexity up and running, Perera anticipates the satisfaction of soon being
able to share the IWU group’s work with the world. First up is an academic paper on
the project’s instrumentation, projected for later this year. And he looks forward
to the day — soon, he hopes — when the device is fully functioning in its purpose
to aid astronomers and astrophysicists in the quest to better understand the nature
of cosmic dust.
“There is still much we don’t know about dust-obscured environments,” says Perera.
“But knowing about the properties of the dust tells us how that dust was created,
and that’s a piece of information about how a planetary system evolved or how a new
planetary system was made.”
Perera notes the field of astronomy is currently preoccupied with asking the question
of how life came to be, with the role of cosmic dust explored within that question.
“I can understand that, because as a child in Sri Lanka, my interest in science was
born, in part, that way as well,” he recalls. “Looking at the stars, and wondering
if there was someone looking back from another planet.”
Perera and his students continue pursuing the answers to those questions, but stand
proud of what their work has already added to the growing body of knowledge for all
those who still seek.
Click here to read a related story on Ryan Schonert '16. Click here to visit Illinois Wesleyan's Physics Department.