The EXCITE mission is set to launch a scientific balloon to observe the atmospheres of exoplanets using infrared technology, focusing on hot Jupiters.
This EXCITE is designed to study atmospheres around exoplanets, or worlds beyond our solar system, during circumpolar long-duration scientific balloon flights. But first, it must complete a test flight during NASA’s fall 2024 scientific ballooning campaign from Fort Sumner, New Mexico.
“EXCITE can give us a three-dimensional picture of a planet’s atmosphere and temperature by collecting data the whole time the world orbits its star,” said Peter Nagler, the mission’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Only a handful of these types of measurements have been done before. They require a very stable telescope in a position to track a planet for several days at a time.”
Unveiling Hot Jupiters
EXCITE will study hot Jupiters, giant gas exoplanets that complete an orbit once every one to two days and have temperatures in the thousands of degrees. The worlds are tidally locked, which means the same side always faces the star.
The telescope will observe how heat is distributed across the planet, from the scalding hemisphere facing the star to the relatively cooler nightside.
It will also determine how molecules in a world’s atmosphere absorb and emit light over the entire orbit, a process called phase-resolved spectroscopy. Not only can this data reveal the presence of compounds — like water, methane, carbon dioxide, and others — but also how they circulate globally as the planet orbits its star.
A Leap in Exoplanetary Science
NASA’s Hubble, James Webb, and retired Spitzer space telescopes have collected a handful of these measurements between them.
In 2014, for example, Hubble and Spitzer observed an 60 hours of Hubble time and 46 hours from Spitzer. Resource-intensive studies like this on space-based observatories are difficult. Time is a limited resource, and studies must compete with hundreds of other requests for that time.
The Benefits of Balloon-Based Observatories
“During its first science flight, EXCITE aims to fly for over a dozen days from the Columbia Scientific Balloon Facility’s site in Antarctica,” said Kyle Helson, an EXCITE team member and a research scientist at the University of Maryland, Baltimore County and NASA Goddard. “And at the pole, the stars we’ll study don’t set, so our observations won’t be interrupted. We hope that the mission will effectively double the number of phase-resolved spectra available to the science community.”
EXCITE will fly to about 132,000 feet (40 kilometers) via a scientific balloon filled with helium. That takes it above 99.5% of Earth’s atmosphere. At that altitude, the telescope will be able to observe multiple infrared wavelengths with little interference.
Collaboration and Future Prospects
“The telescope collects the infrared light and beams it into the spectrometer, where it kind of goes through a little obstacle course,” said Lee Bernard, an EXCITE team member and a graduate research assistant at Arizona State University in Tempe. “It bounces off mirrors and through a prism before reaching the detector. Everything must be aligned very precisely — just a few millimeters off center and the light won’t make it.”
The spectrometer rests inside a vessel called a cryostat situated behind the telescope. The cryostat cools the spectrometer’s detector — once a flight candidate from Webb’s NIRSpec (Near InfraRed Spectrograph) — to about 350 degrees below zero website for real-time updates of a balloon’s altitude and
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