NASA’s Balloon Mission GUSTO Maps the Space Between the Stars

Scientists and engineers near McMurdo Station in Antarctica are preparing to release a NASA experiment to explore the universe by balloon.

Scheduled to launch no earlier than Dec. 21, the airborne telescope called GUSTO — the Galactic/Extragalactic ULDB Spectroscopic Terahertz Observatory — will peer between the stars from roughly 23 miles (37 kilometers) above Earth’s surface. There, the observatory, while suspended from a balloon the width of a football field, will spend at least 55 days examining a 100-square-degree area of the sky, using far-infrared detectors to help scientists make a 3D map of a large part of the Milky Way and determine the abundances of elements critical to life, including carbon, oxygen and nitrogen.

“With GUSTO, we’re really trying to trailblaze,” said Kieran Hegarty, program manager for GUSTO at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, which leveraged its more than two decades of experience building and flying balloon missions to design and build the project’s solar arrays and the gondola that will carry the telescope. “We want to continue to demonstrate that balloon investigations return compelling science.”

As the first balloon-borne experiment in NASA’s Explorer program, GUSTO will have the same scientific reach as the agency’s spaceborne satellites, such as TESS (the Transiting Exoplanet Survey Satellite) and IXPE (Imaging X-Ray Polarimetry Explorer).

Functioning as a cosmic radio, GUSTO will “listen” to high-frequency signals emitted by carbon, oxygen and nitrogen atoms within enormous molecular clouds of dust and gas that accumulate between the stars. Such observations are impossible to do with Earth-based telescopes because of water vapor in the atmosphere, which absorbs the light emitted from these atoms. GUSTO will fly above most of that water vapor. “For the type of science we do, it’s as good as being in space,” said Chris Walker, principal investigator of GUSTO at the University of Arizona.

As the telescope follows air currents around the South Pole, scientists will map the intensity and velocities of these signals, allowing them to later connect the dots and create an image of the emissions.

What’s more, GUSTO will reveal the 3D structure of the Large Magellanic Cloud, or LMC, a dwarf galaxy near the Milky Way. The LMC resembles some galaxies of the early universe that NASA’s James Webb Space Telescope is exploring, but being billions of light-years closer, the LMC will be much easier for scientists to examine in detail.

“By studying the LMC, comparing it to the Milky Way, we’ll be able to understand how galaxies evolved from the early universe until now,” Walker explained.

With seals and penguins nearby, a dozen mission team members from APL and the University of Arizona are performing the final checks before GUSTO’s launch. Once in the air, the APL team will monitor the health and status of the gondola while data collected by the observatory will be transmitted back to the team at the University of Arizona science operations center for analysis.

For Walker, the project represents some 30 years of effort, the outgrowth of many experiments from Earth-based telescopes and other balloon efforts.

“We all feel very fortunate and privileged to do a mission like this — to have the opportunity to put together the world’s most advanced terahertz instrument ever created, and then drag it halfway around the world and then launch it,” he said. “It’s a challenge, but we feel honored and humbled to be in the position to do it.”

GUSTO is a collaboration between NASA, the University of Arizona, APL, the Netherlands Institute for Space Research (SRON), the Massachusetts Institute of Technology, the Jet Propulsion Laboratory, the Smithsonian Astrophysical Observatory and others.

Track GUSTO's Journey around the South Pole.

Adapted from a NASA release