In a crowded basement laboratory on Johns Hopkins' Homewood campus, astrophysicist Stephan McCandliss and a small team of students, electricians, and machinists are building—from scratch—a $3.2 million NASA sounding rocket called the Far-ultraviolet Off Rowland-circle Telescope for Imaging and Spectroscopy: FORTIS, for short.
Over the last six years, they have sweated over the placement of each component, screw, and wire on this new kind of spectro-telescope, which will be launched on a trajectory 180 miles into the sky later this fall from White Sands Missile Range in the desert of New Mexico on a mission to wrest secrets from the universe. Specifically, the team hopes to determine how ultraviolet light emitted by hydrogen—referred to as the "Lyman alpha line" in honor of its 1906 discovery by Theodore Lyman—manages its great escape from the dusty confines of star-forming galaxies.
Students, both undergraduate and graduate, are involved in many aspects of this complex project, from the design and construction of the 1,110-pound 24-foot rocket payload through its testing and launch, and, eventually, the post-flight analysis of the data it collects, which the team hopes will shed new light on the emergence of the ionized universe.
"Escaping Lyman alpha radiation can tell us a lot about different kinds of problems, such as how gas gets ionized by hot stars, how hot dust forms in the expanding winds of stars and supernovae, and how dust gets dispersed throughout a galaxy. What we are looking for is fundamental stuff. Yes, the interaction of Lyman alpha radiation with dust is esoteric, but it's also not well-understood. It's important because, well, dust ultimately becomes us. It's what we are made of," says McCandliss, one of the current principal investigators for the Johns Hopkins University Sounding Rocket Program, which has launched 79 sounding rocket experiments and produced 40 PhDs since its inception in 1961.
"Sounding" rockets (which take their name from nautical terminology, where weights are thrown overboard to gauge the depth of the sea) are instrument-carrying rockets designed to take scientific measurements at altitudes between those that can be reached by weather balloons and by satellites. They reach space but don't go into orbit. The JHU sounding rocket experiments in astronomy are designed specifically to probe emissions from heavenly bodies. Comet Hale-Bopp and the so-called Dumbbell Nebula, located 1,360 light-years from Earth, are among the past targets.
"With perseverance, attention to detail, and a bit of luck, each instrument goes up and comes down telling us something fundamental about the universe that we didn't know before the launch," McCandliss says. "Each payload is designed to explore a new science thrust, as enabled by some new technology, and provide a hands-on training ground for the next generation of space scientists. We call the new payload a spectro-telescope because it is designed to acquire both images and spectra, essentially simultaneously."
The students on the team learn the science and art of sounding rockets in a system not unlike that of an old-fashioned guild, in which knowledge is passed from one generation to another verbally and by hands-on experience. "This is the kind of training and experience that I really don't think is available, at least in this way, anywhere else that I know of," says McCandliss. "When you are part of a team that builds these instruments, you learn by doing, by getting your hands dirty. Our students are involved in every aspect of the project, beginning with the definition of science goals and measurement objectives that flow down into the instrument requirements and inform the systems engineering of the design, fabrication, and testing phases of the mission."
This freedom to be involved in almost every aspect of the rocket's construction, launch, and data analysis is what attracts top astrophysics and engineering students from all over the country to the Johns Hopkins program. Just ask 28-year-old Brian Fleming of Anchorage, Alaska, a graduate of the Illinois Institute of Technology.
"I started off in the sounding rocket program at Johns Hopkins as an excellent screw driver fetcher and heavy thing lifter, and now I am in my sixth year and basically doing everything and have a great sense of ownership over the project," says Fleming, who admits that other than constructing a shed when he was 12 with his father, he never built anything before landing at Johns Hopkins. "The greatest thing for me about the sounding rocket program is that I am allowed to do everything. If I worked on a big satellite project, I would be [assigned] to an unimportant calibration off in a dark room somewhere because if I touched anything important, I would certainly break it. Here at Johns Hopkins, I can get my grubby little fingers into everything. I think it's been the best learning experience for what I want to do that I could possibly have had."
Keith Redwine, a 23-year-old second-year grad student from Boston, agrees. Redwine, who got his undergraduate degree at Columbia University, was attracted to the Johns Hopkins sounding rocket program by the opportunity it presented to be involved in the project in all aspects, from fabrication to launch—and beyond.
"In many research groups, a grad student in astrophysics—like me—would sit and write software for his or her five years in school," Redwine says. "In the FORTIS group, if I get tired of software, I can go solder some cables or cut some parts in the shop. It can't ever get boring because there is such a wide range of stuff that needs to be done. And I can say that I am actually a rocket scientist."
Graduates of the sounding rocket program end up with more than mere bragging rights, though. Many of the 40 PhDs to come out of the program have gone on to fill key roles in a host of NASA space missions, including the Advanced Camera for Surveys, the Cosmic Origins Spectrograph on the Hubble Space Telescope, the Mercury Messenger Mission, and the Galaxy Explorer. Some have even gone on to become principal investigators, leading missions on quests to uncover ever more "secrets of the universe."
Modest little FORTIS will begin to address such puzzles by spending slightly more than five minutes on target in the sky, during which time the doors of the microshutter array (a device the size of a thumbnail with 128 x 64 tiny doors) will be latched open for 30 seconds, allowing an image to be recorded and analyzed "on the fly" for selection of the bright spectral targets to be observed for the duration of the flight.
Once the rocket makes its landing in the desert and is retrieved, McCandliss and his team will analyze those images and spectra, and the data they provide. They also will fix anything that is broken and prepare the payload for another shot to take place about a year later.
More than six years' worth of meticulous work to get a rocket airborne for less time than it takes most of us to take a shower? Absolutely.
According to the team, you would be surprised at how much information these rockets can gather in that short time, mainly because they are about 100 times less expensive than satellites, can be developed quickly (compared, again, to satellites), and can study targets in the ultraviolet and X-ray portions of the electromagnetic spectrum that cannot be seen from the surface of the Earth.
"The five minutes of data acquired during the course of a sounding rocket mission give the student an opportunity to develop and quantify a unique story that can't be addressed by existing instruments," McCandliss says. "For FORTIS, it's a story of emergence: of stars, of light, and ultimately, of the seeds of life."
Added to that, of course, is the invaluable opportunity it presents to students.
"We get a scientifically and technologically literate individual, versed in that demanding discipline of launching delicate instruments on hurling machines for the purpose of wresting secrets from the universe," he says. "For them, the sky is no longer the limit."