Operation Argus was a series of United States low-yield , high-atmosphere nuclear weapons tests and missile tests secretly conducted during August and September 1958 over the South Atlantic Ocean . The ARGUS tests took 11 days from start to finish with the first launch on August 27 and the final launch on September 6 . They were performed by the Defense Nuclear Agency , in conjunction with the Explorer 4 space mission . Operation Argus was conducted between the nuclear test series '' Operation Hardtack I '' and '' Operation Hardtack II '' . Contractors from Lockheed Aircraft Corporation as well as a few personnel and contractors from the U.S. Atomic Energy Commission were on hand as well
Operation Hardtack II
Operation Hardtack II
Operation Argus