Galactic Radiation and Background

Though only two of the five satellites made it into orbit, they returned a wealth of information on Soviet air defense radar capabilities as well as useful astronomical observations of the Sun.

The United States Air Force began a program of cataloging the rough location and individual operating frequencies of these radars, using electronic reconnaissance aircraft flying off the borders of the Soviet Union.

Some experiments were carried out using radio telescopes looking for serendipitous Soviet radar reflections off the Moon, but this proved an inadequate solution to the problem.

The project was restarted under the name "Walnut" (the satellite component given the name "DYNO"[1]: 140, 151 ) after heightened security had been implemented, including greater oversight and restriction of access to "need-to-know" personnel.

The Navy had wanted to determine the role of solar flares in radio communications disruptions[7]: 300  and the level of hazard to satellites and astronauts posed by ultraviolet and X-ray radiation.

Moreover, solar output is unpredictable and fluctuates rapidly, making sub-orbital sounding rockets inadequate for the observation task.

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 final scheduled GRAB flight was canceled,[7]: 300–303  and the satellite intended for the mission was ultimately donated to the National Air and Space Museum in 2002.