This unprecedented five-in-one mission, called "Composite 1" and "Buckshot", ended in failure on 24 January 1962 after its Thor-Ablestar's second stage failed to deliver the payloads to orbit.

After Vanguard, the Navy's next major goal was to use the observational high ground of Earth's orbit to survey Soviet radar locations and frequencies.

The Earth's atmosphere blocks large sections of sunlight's electromagnetic spectrum, making it impossible to study the Sun's X-ray and ultraviolet output from the ground.

Without this critical information, it was difficult to model the Sun's internal processes, which in turn inhibited stellar astronomy in general.

[5]: 5–6  On a more practical level, it was believed that solar flares directly affected the Earth's thermosphere, disrupting radio communications.

Three of the photometers were shielded against Van Allen radiation belts (which could spoil results) by magnets, as had been done on earlier missions.

They were reinstated on SOLRAD 4 not for solar study, but for night-time measurement to see if ambient Lyman-alpha radiation constituted a threat to astronauts and satellites.