If all goes as planned, by the end of December, the newest iteration of the Balloon-borne Large Aperture Submillimeter Telescope, or BLAST, will be ready for takeoff—this time bigger and better than ever before.
A crew of researchers from Penn, led by Mark Devlin, the Reese W. Flower Professor of Astronomy and Astrophysics in the School of Arts and Sciences, have already made the long trek to Antarctica for the experiment with their collaborators from NASA and several other universities.
For about three weeks, the most sensitive telescope of its kind to be carried by a balloon will float 120,000 feet up—four times as high as an airplane would fly—to the edge of space, surveying molecular clouds in the Earth’s galaxy, collecting data that can help measure how stars form.
Ballooning in astronomy, notes Devlin, a cosmologist who studies the origins of the universe, is essentially a “poor person’s satellite.”
“A satellite costs a billion dollars or more, a balloon launch costs traditionally quite a bit less,” he explains. “With a balloon, you go above most of the atmosphere; about 99.5 percent of the atmosphere is below you and you can get a very clear view of what is going on.”
At sea level, the atmosphere is opaque at the submillimeter part of the spectrum, “in other words, you can’t see anything,” he adds. “So if you were to look up with a telescope here, you would just see black, there would be nothing to see. You have to get above most of the atmosphere.”
The balloon-borne telescope that will lift off from McMurdo Station in mid-December has been designed, built, and tested, mostly in the high bay on Penn’s campus, since 2013. But, the idea of BLAST dates back to 2001. A series of flights for different versions of the telescope, which initially looked only at external galaxies and their star-forming regions, took place in New Mexico and Sweden, as well as in Antarctica—the most successful happening in 2006 (a movie by Devlin’s filmmaker brother detailed the experience). Each project so far has yielded new evidence about star formations and inspired additional in-depth experiments.
Results from the 2006 flight of BLAST showed that there were enough star-forming regions in our galaxy to form 70 to 80 stars per year. Yet, the actual number of stars being formed is more like four stars annually. With BLAST, Devlin and his team hope to figure out what factors are at play—such as gravity, energy, and magnetic fields.
“When we look at these star-forming regions, if the light is polarized and very uniform across the entire cloud, then you would surmise that the energy is dominated by the magnetic fields,” says Devlin. “If it’s completely disordered because the turbulence is messing things up all over the place, then you would come to the conclusion that the turbulence was dominating the energetics of the cloud. That’s what we’re looking for.”
The new BLAST has improved immensely in terms of its capabilities, notes Devlin, with upgraded technology and almost 10 times as many detectors than before, “which obviously makes it a much more sensitive instrument.” There’s also a significantly larger mirror, Devlin says, allowing researchers to see smaller features within the clouds.
It took a “fair amount of expertise” to get BLAST to where it is today, Devlin says, adding that there’s a “whole slew of skillsets you need to make this happen.” He’s been able to add people from all over the world to the team who’ve contributed to BLAST’s formation, operation, and mechanics.
The massive, 5,000-pound balloon-borne telescope was sent to the southernmost continent in pieces via trucks, airplanes, and even a boat. Antarctica is the best setting for this type of test, as its 24/7 sun provides a stable temperature for the 27 million cubic foot helium balloon, and the ability to recharge its batteries powered by solar panels. It’s also extremely important the experiment takes place in a remote location away from where many people live, because it has to come down somewhere—“and is best if it is not near any populated areas,” Devlin says.
Nate Lourie, now a postdoctoral researcher in Devlin’s lab, has worked on BLAST since 2012, when he started his Ph.D. program at Penn in physics and astronomy. A tinkerer at heart, he’s always wanted to make things going into space.
“Students here get to make so much,” he says. “We’ve touched everything that’s on this experiment. We’ve developed it, we’ve designed it, we put it all together. When it breaks, we’re the ones who have to fix everything.”
Lourie, who is joining Devlin and the team in Antarctica, is feeling good about the balloon’s flight, he says, “better than I have in the past.” That confidence is mainly due to a “dress rehearsal” the team conducted with NASA in Texas over the summer.
“We went to Texas with an experiment we were pretty sure was going to work but there were a lot of hurdles we needed to get over,” says Ian Lowe, a fourth-year physics Ph.D. student, who’s been working on BLAST, too, during his tenure at Penn. “The whole team was there from all of the different institutions for a month and a half or so.”
In Texas, the entire BLAST team slowly crossed everything off the list, fixing helium leaks, perfecting the readout system, and putting everything together for the first time.
“The mirror just went on smoothly,” says Lowe. “One after another, everything started to work. It was really exciting to watch that evolution.”
Most exciting for Gabriele Coppi, a postdoc working with Devlin on BLAST, as well as the Simons Observatory project, which builds state-of-the-art telescopes and cameras for use in northern Chile, is the fact that the novel data that comes out of this experiment is “going to be used by the scientific community”—and a large portion of it, at that.
“It’s not going to change anybody’s everyday life on whether or not we understand how stars form in our galaxy,” says Devlin. “But what astronomers and cosmologists and astrophysicists are trying to do is fill the picture, to have a complete understanding of what’s happening in the universe, and this is one part of that. It’s a question that is part of a puzzle.”
Penn’s collaborators on BLAST span various institutions, including Arizona State University, University of Virginia, Northwestern University, National Institute of Standards and Technology, Cardiff University, University of New South Wales, University of Southern California, National Radio Astronomy Observatory, Nagoya University, University of California San Diego, University of California Davis, Stanford University, Canadian Institute for Theoretical Astrophysics, University of British Columbia, Max-Planck Institute for Astronomy, Università Milano-Bicocca, University of California Berkeley/Lawrence Berkeley National Laboratory. Supporting agencies include NASA and its Columbia Scientific Balloon Facility and the National Science Foundation and its U.S. Antarctic Program.
Homepage photo: Mark Devlin, the Reese W. Flower Professor of Astronomy and Astrophysics in the School of Arts and Sciences, works on BLAST at Penn’s high bay.
