NASA Wanted To Study The Milky Way, So It Launched a Stadium-Sized Balloon From Antarctica

As diamonds and gemstones bejeweled into a fabric, the tapestry of cosmic space is speckled with billions of trillions of stars that scintillate and dazzle in vibrant hues. For astronomers, these glittery clusters of stars are intriguing data packages that can reveal valuable information about the evolution of the universe. Turns out, even the space between these stars isn’t insubstantial either. Also called “interstellar medium (ISM),” this space isn’t empty, as it may seem to the naked eye. Rather, it pulses with hot radiating material left over as the last words of dying stars.

To study this ISM in detail, NASA scientists developed a state-of-the-art instrument: a stadium-size balloon. In December 2023, this 39 million cubic-foot balloon lifted off from McMurdo research station in Antarctica, carrying s telescope within its gondola. The telescope was designed to collect treasured information about the ISM, which could offer clues to how the planets, stars, and the overall cosmos evolved, NASA described in a press release.

The mega GUSTO balloon took flight on December 31, 2023, from Ross Ice Shelf, the largest ice shelf in Antarctica. Scientists described the moment of launch as a “high drama spectacle.” Support trucks driven out onto the ice shelf piped helium into the balloon. The balloon luffed and flapped "like a sail" as it was being filled. As helium poured inside it, it inflated. Once the balloon was ready, the scientists blasted it off upwards. Rising rapidly, the balloon rumbled as it unfurled, according to the University of Arizona, which supplied infrared technology for the balloon.

This balloon was designed as part of NASA’s GUSTO (Galactic/Extragalactic ULDB Spectroscopic Terahertz Observatory) mission. After lifting off from the launchpad, the telescope was supposed to float 128,000 feet above Antarctica’s skies for at least 55 days, and travel to the delicate seam between the Earth’s atmosphere and the stratosphere, in a record-breaking flight.

The balloon-borne telescope was equipped with a “cosmic radio,” fashioned to “listen” to the cosmic ingredients and collect information about the chemical makeup of ISM. The radio featured line detectors for detecting and listening to the signals of carbon, oxygen, and nitrogen in the ISM. It would shoot extremely high-frequency radio waves in the ISM and carve a 3D map of a large segment of the Milky Way while tracing its material via cosmic sounds. According to the Harvard & Smithsonian Center for Astrophysics, ISM, the region between stars inside a galaxy, is “home to clouds of gas and dust,” also known as “molecular clouds.” 

These gigantic clouds are primordial masses of cold and dust accumulated over time by collapsing stars and burning planets, some of which smell like a “charred hamburger on a grill.” When jumbo-sized stars die or explode in a supernova, intense shock waves ripple through these clouds. Amid the right conditions, these cloudy remnants combine to form new, young stars. The swirling disk of material hanging around these younger stars can also result in the birth of new planets. “GUSTO is unique in its ability to examine the first part of this process, to understand how these clouds form in the first place,” Chris Walker, lead investigator of GUSTO at the University of Arizona, said in the press release. 

“We basically have this radio system that we built that we can turn the knob and tune to the frequency of those lines. And if we hear something, we know it's them. We know it's those atoms and molecules,” he explained. It took the team a long time to boil down the launch location to Antarctica while they combed the map to search remote areas for the project where the balloon could float with stability. One reason for selecting Antarctica was that it gets constant sunlight during the summer. Plus, the atmospheric zone around the South Pole generates cold rotating air, creating a phenomenon called an “anticyclone,” which would enable the balloon to fly in circles without disturbance.