At the University of Arizona, the edge of space is closer than it may seem. Just a few minutes south of main campus by car, to be exact. There, at the University of Arizona Tech Park at The Bridges, a new "high bay" facility under construction will allow researchers and engineers to build and test hardware for experiments and missions designed to fly at extremely high altitudes sometimes referred to as the "edge of space," a fuzzy, ill-defined transition zone between Earth's atmosphere and space. 

Carol Stewart, associate vice president of Tech Parks Arizona, said the facility was designed with the specific purpose of accommodating large pieces of flight hardware, such as research platforms mounted on balloon-borne gondolas or small payloads for space missions. Officially named the Mission Integration Laboratory, or MIL, the tall, hangar-like building will feature an overhead crane and have space for an environmental chamber to simulate conditions at the edge of space.

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Here, researchers and students can work on instruments, telescopes and high-altitude balloon technology. The facility will make UArizona even more competitive for top-dollar research missions such as NASA's Long Duration Balloon flight missions, and will help attract corporations looking to advance their tech through public-private partnerships.

"We have a proud history of being a world-leading institution in astronomical research, and the new Mission Integration Lab is going to help us sustain and grow our research programs in the coming decades," said Buell Jannuzi, director of Department of Astronomy and Steward Observatory in the UArizona College of Science. "In particular, the Mission Integration Lab, with its spacious high bay, is perfect for integrating the instruments, telescopes and high-altitude balloons that together will meet the demands of NASA's ongoing program of Long Duration Balloon flight missions. This facility will help our talented faculty win the right to lead more of these missions, which can be at the level of tens of millions in contracts to the university."

Floating at the edge of space

Balloon-borne missions fill an important niche between ground-based observatories and space telescopes, providing an ideal way to deploy telescopes and other instruments to altitudes where they experience less interference from Earth's atmosphere without necessitating a full-blown space mission, Jannuzi explained.

"One hundred twenty thousand feet is not exactly outer space, but it's as close as we can get there without spending a huge amount of money," he said, "and for many science objectives, that's all you need."

Dan Marrone is one of several UArizona researchers pursuing balloon-borne astronomy. He is a co-investigator on the Terahertz Intensity Mapper, or TIM, a NASA-funded balloon mission designed to create a giant map of galaxies over 5 billion years of cosmic history. His research team helps develop an imaging spectrometer capable of detecting extremely faint galaxies in the "cosmic afternoon," the time when star formation in the universe was slowing down from its peak 10 billion years ago.

"The MIL allows us to assemble and thoroughly test the TIM payload so that we're ready to make it work in a short Antarctic summer when we have to fly it. This will be the first place that we put together the whole 5,000-pound payload that will be going to the edge of space," Marrone said.

Inside the tall hangar, the team of scientists and engineers will be able to suspend the entire balloon payload, which is almost 30 feet tall, from an overhead crane. They will assemble it, test it and let it drive itself under its own power, he explained.

Once the instrument is built, Marrone and his team will take it to Mount Graham near Safford, about three hours east of Tucson, and mount it to the Large Binocular Telescope in a simulated "test flight" at an altitude of 10,000 feet, high enough for the atmosphere to allow through a little of the far-infrared light TIM sees. Next will be an actual test flight on a balloon in New Mexico, and then the TIM instrument will be shipped to McMurdo Station in Antarctica to be prepared for launch, which is currently slated for late 2024. Suspended underneath a giant balloon, the telescope will ride a seasonal wind vortex that will take the observatory on a circular flight trajectory over Antarctica at a 24-mile altitude, from where it will observe the night sky, unobstructed by much of Earth's atmosphere. 

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Another balloon-borne observatory spearheaded by UArizona is GUSTO, which is led by Christopher Walker, a professor of astronomy with joint appointments in the James C. Wyant College of Optical Sciences and College of Engineering. Short for Galactic/Extragalactic ULDB Spectroscopic Terahertz Observatory, the mission is funded by NASA and has been approved for launch in December 2023. GUSTO will carry an infrared telescope to study the life cycle of stars in the interstellar medium, from their birth out of condensing molecular clouds in stellar nurseries to their evolution and death to their reseeding the interstellar medium with the ingredients for new stars.  

Stadium-sized balloons

"These telescopes are actually pretty big – ours is 7 feet in diameter – and they tend to work at wavelengths that are absorbed by the atmosphere," Marrone said. "Only when they're at high altitude can they get a clear view of the far-infrared part of the spectrum. Typically, they look at emission from molecules, dust or gas in space."

The high bay facility must be sufficiently large to accommodate these platforms during their development and testing phase.

"You need to be able to test their functionality without having to blow up a balloon or launching them on a rocket," Jannuzi said. " And that means having a big space with a crane where the team can suspend the payload, walk around it and work on it while it's suspended from the ground."

Some balloon-borne payloads are large and heavy enough to require balloons that rival Arizona Stadium in size, according to Steward Observatory Research Manager Brian Duffy. He explained that a typical Long Duration Balloon flown over Antarctica contains up to 40 million cubic feet of helium and can lift a payload of 6,000 pounds. Floating at a cruising altitude between 120,000 and 125,000 feet, the balloon expands to about 400 feet.

"The MIL is based on the design of NASA's Long Duration Balloon hangars in Antarctica," Duffy said. "It is specifically designed to facilitate and support the initial integration and testing of LDB payloads prior to test flight and shipment to Antarctica."  

High bay for hire

The new facility will include a thermal vacuum chamber, where engineers can expose small flight hardware or components of larger payloads to the harsh environments they will encounter after launch, such as extreme heat or cold and little or no atmospheric pressure. The facility will complement a thermal vacuum chamber in the Applied Research Building, currently under construction on the UArizona campus.

Even instruments for ground-based telescopes could be tested in the high bay, Jannuzi explained.

"Some of the testing will require pointing a telescope at a planet or a bright star," he said. "What's nice about the space is that it's not only big, but it's also easy to open it up and get your instrument on the sky right then and there."

"The Mission Integration Lab expands the University of Arizona’s capacity for space-based research requiring high bay facilities," said Elizabeth "Betsy" Cantwell, UArizona senior vice president for research and innovation. "Not only will this facility enable the university to remain at the forefront of Research I institutions for astronomy, it will also open opportunities to partner with key space-related industries and drive economic development in southern Arizona."

Available for government-funded research and private industry projects, the high bay complements other research and development facilities across campus to provide a one-stop ecosystem for space and low-orbit application research, Jannuzi said.

Located at the UA Tech Park at The Bridges, with close proximity to main campus as well as a planned connection to the university's CatTran shuttle network, the facility will provide access to an exceptional infrastructure of technology, research and development, he added. Jannuzi emphasized UArizona's unparalleled diversity of capability in terms of testing, assembly, refurbishment and workforce education.

"We have more research coming our way than we can house at the moment," he said, "and so we are responding by building more facilities like this one, which enables us to take on more cutting-edge science and technology."