A High Energy Fleet . ... Courtesy: MSFC Historical Archive , NASA Explanation: Like a fleet of futuristic starcruisers, NASA's highly successful series of High Energy Astrophysical Observatory (HEAO) spacecraft appear poised over planet Earth. Labeled A, B, and C in this vintage illustration, the spacebased telescopes were known as HEAO-1 , HEAO-2 , and HEAO-3 respectively. ... HEAO-3, the last in the series, was launched in 1979 and measured high energy cosmic-ray particles and gamma-rays . ...