The Elektrons were two pairs of early Soviet scientific spacecraft, launched in 1964, which observed Earth's inner and outer radiation belts, cosmic rays, and the upper atmosphere. One of each pair (Elektrons 1 and 3) were placed in a lower orbit to take measurements of the inner Van Allen belt; the other of each pair (Elektrons 2 and 4) were placed in a higher orbit to study the outer Van Allen belt.