Getting EXCITEd about studying hot Jupiters

In 2012, members of the EXoplanet Climate Infrared TElescope (EXCITE) team began ideating a balloon-borne instrument to measure the spectra of hot Jupiters, gas giant exoplanets with short orbits and large temperature gradients. After over a decade of planning, financing, and building, NASA’s EXCITE was finally ready to launch, and on August 31, 2024, EXCITE took to the skies for its first test flight.

Rehm et al. presented the initial results from that test flight.

“Hot Jupiters are great testbeds for demonstrating the observational techniques we use to characterize exoplanet atmospheres,” said author Tim Rehm. “The observing techniques that EXCITE will verify may also become applicable to smaller exoplanets, such as mini Neptunes and super Earths, which are more similar to our planet, but hot Jupiters themselves are scientifically interesting exoplanets: They can reveal information about the evolution of planetary systems far different from ours.”

EXCITE specializes in performing phase-resolved spectroscopy of hot Jupiters, something less feasible with other existing spectroscopic instruments such as the Hubble Space Telescope or the James Webb Space Telescope.

“This is because they are resource-intensive observations; they require a near-transparent foreground and 1-3 days of continuous observations to capture the full orbit of a single hot Jupiter,” Rehm said.

The EXCITE test flight provided a valuable opportunity to test how the instrument behaves in the field and focused on exploring the operational ranges and performance of subsystems.

“Overall, the test flight helped us understand and verify how our instrument will behave in the stratosphere and illuminated a few small changes that will optimize EXCITE’s performance during a long duration balloon (LDB) flight,” Rehm said.

The team is looking forward to its first official LDB flight in Antarctica during the winter of 2026-2027.

Source: “The EXoplanet Climate Infrared TElescope (EXCITE): A balloon-borne mission to measure spectroscopic phase curves of transiting hot Jupiters,” by T. D. Rehm, C. Altermatt, L. Bernard, A. Bocchieri, N. Butler, O. Carey, R. C. Challener, J. Hartley, K. R. Helson, D. P. Kelly, K. Klangboonkrong, A. L. Korotkov, M. Lally, E. Leong, N. K. Lewis, S. Li, M. Line, S. F. Maher, R. McClelland, L. V. Mugnai, P. C. Nagler, C. B. Netterfield, V. Parmentier, E. Pascale, J. Patience, L. J. Romualdez, P. A. Scowen, G. S. Tucker, and I. Waldmann, Review of Scientific Instruments (2026). The article can be accessed at https://doi.org/10.1063/5.0326026 .