XL-Calibur will collect measurements at about 125,000 feet (38,100 meters) in the air, above 99.97% of the Earth’s atmosphere. Here, the instrument rises shortly after launch.
Scientists from Washington University in St. Louis have launched XL-Calibur, a balloon-borne telescope, to unlock the secrets of astrophysical black holes and neutron stars, some of the most extreme objects in the universe.