opportunity. The Navy had wanted to determine the role of solar flares in radio communications disruptions and the level of hazard to satellites and astronauts posed by ultraviolet and X-ray radiation. Such a study had not previously been possible, as the Earth's atmosphere blocks much of the Sun's X-ray and ultraviolet output from ground observation. Moreover, solar output is unpredictable and fluctuates rapidly, making sub-orbital sounding rockets inadequate for the observation task. A satellite was required for long-term, continuous study of the complete solar spectrum. The NRL already had a purpose-built solar observatory in the form of Vanguard 3, which had been launched in 1959. Vanguard 3 had carried X-ray and ultraviolet detectors, though they had been completely saturated by the background radiation of the Van Allen radiation belt. Development of the DYNO satellite from the Vanguard design was managed by NRL engineer Martin Votaw, leading a team of Project Vanguard engineers and scientists who had not migrated to NASA. The dual-purpose satellite was renamed GRAB ("Galactic Radiation And Background"), sometimes called GREB ("Galactic Radiation Experiment Background"), and referred to in its scientific capacity as SOLRAD ("SOLar RADiation"). Operational history The first GRAB satellite, SOLRAD 1, was launched 22 June 1960, on the same rocket as Transit 2A, an early naval navigation satellite. GRAB 1 had the distinction of being the first successful U.S. intelligence satellite, returning electronic intelligence (ELINT) data from 5 July 1960, until 22 September 1960, totaling 22 data collection passes of 40 minutes each over the Soviet Union, China and their allies. The SOLRAD experiment remained operational for ten months (though usable data was obtained only for five months) and it returned the first real-time X-ray and ultraviolet observations of the Sun. During the second launch attempt, the Thor booster shut down 12 seconds early, and the flight was subsequently terminated by range safety, raining fragments over Cuba. To ensure this did not happen again, subsequent launches from Cape Canaveral flew a dogleg trajectory to reach 70° inclination, avoiding the island nation. The other successful GRAB mission, GRAB 2, was launched 29 June 1961, atop the same Thor-Ablestar launch vehicle as Injun, a geophysical science satellite from the University of Iowa, and Transit 4A. GRAB 2 began transmission of intelligence to the ground on 15 July 1962, and functioned in orbit for fourteen months. The amount of data received was so large that automated analytic tools