The HESSI spacecraft is being carried approximately 113 nautical miles to an altitude of about 39,000 feet for release.

Tucked inside a Pegasus XL rocket, attached to the under belly of this Orbital Stargazer L-1011 aircraft, the HESSI spacecraft is being carried approximately 113 nautical miles east-southeast of Cape Canaveral to an altitude of about 39,000 feet for release. During its planned two-year mission HESSI will study the secrets of how solar flares are produced in the Sun's atmosphere. Launch of HESSI in mid-air over the Atlantic Ocean is scheduled for 3:26 p.m. EST