During the ARGUS experiment in mid-1958, three small nuclear devices were exploded in the atmosphere above the South Atlantic to determine the extent to which the Van Allen magnetic field would be affected by nuclear-generated electrons. The Air Force Special Weapons Center assisted ARGUS in its Project JASON, using sounding rockets to take intensive measurements of the electrons introduced into the Van Allen belt. This photo shows JASON launching from Puerto Rico.
Image Credit: AFRL PRS History Office and Archives, Kirtland AFB NM