NASA Using High-Altitude Balloons to Study Particles From Space
Here are some excerpts from the NASA article.
“The balloon is helium-filled and about the size of a football stadium when fully inflated at its operational float altitude of about 110,000 feet…” (33.5 kilometers).
“EUSO-2 will detect ultra-high energy cosmic-ray particles from beyond our galaxy as they penetrate Earth’s atmosphere. The origins of these particles are not well known, so the data collected from EUSO-2 will help solve this science mystery.”
You can read more about it here: https://www.nasa.gov/feature/wallops/2023/two-for-two-nasa-launches-2nd-super-pressure-balloon-from-new-zealand