When it arrives at its cruising altitude, the balloon and gondola will be swept into the circumpolar vortex, a stratospheric wind pattern that will carry the craft in a wide circle high above the perimeter of the Antarctic continent. During an 11- to 14-day flight, the craft will complete one, maybe two, Antarctic laps before landing close to where it launched, at the McMurdo Long-Duration Balloon Facility on the Ross Ice Shelf. 

Those stratospheric winds that will give the balloon a long, smooth flight are one reason that Antarctica is an ideal place for high altitude balloon flight. Another is that the exoplanets EXCITE aims to study never fall below the horizon, so the telescope will be able to stare them down for extended periods of time.

Exploring “hot Jupiters” from the Antarctic cold

Specifically, the telescope is designed to study “hot Jupiters,” a class of exoplanets similar to the gas giants in Earth’s solar system.  What’s “hot” about these giant planets is that they orbit surprisingly close to their host stars, in some cases closer than the orbit of Mercury. As scientists continue to debate how these planets form and evolve, hot Jupiters provide a unique opportunity to study some of the most extreme atmospheric conditions in the known universe. That’s what the EXCITE instrument aims to do.  

Most hot Jupiters are tidally locked with their host stars, meaning one side of the planet is forever fried by its sun, while the rest hides in eternal darkness. The difference in temperature between the hot side and cold side drives wind speeds that can exceed 1,000 miles per hour. The orbits of these planets are incredibly fast, with some completing their solar year in just a few Earth days. That means that during its nearly two-week mission, EXCITE will follow individual planets through their full orbital cycles. 

“The planets have phases basically like our Moon,” said Greg Tucker, a professor of physics at Brown and an EXCITE team member. “When the planet is in front of the star, we're seeing its night side, and when it’s just about to go behind the star, then we’re seeing it fully illuminated.”

By viewing the planets through full orbits, scientists can get a fuller picture of their atmospheric dynamics, including wind speeds and chemical compositions. This will be Tucker’s fourth Antarctic trip. He was there for two previous balloon missions and a ground-based experiment at the South Pole. 

“The scenery is great, if you like ice,” he said. “There's some wildlife, basically penguins, whales, seals and skuas, which are like seagulls — very aggressive seagulls.”

It will be the first Antarctic expedition for Klangboonkrong and fellow graduate student Caitlyn Altermatt, who is also a member of the EXCITE team. A third graduate student and team member, Oliver Carey, will monitor the mission from back home in Providence. 

“I'm very excited to go,” Altermatt said. “I'm a winter person and an optimist, which helps. I have a pair of cross-country skis that I’m packing, so between the science and the opportunities for recreation, I'm ready.”

If all goes to plan, NASA will retrieve the telescope and all its on-board data and instruments shortly after the mission. There’s a chance, however, that the balloon could land further from its intended touchdown area than expected. If that’s the case, the team may have to wait until next year to get it back, Tucker says. 

Either way, the telescope will transmit data throughout the mission, so the researchers are confident that it will provide new insights into giant planet formation and the evolution of their dynamic atmospheres.