Identical payload to the Nimbus-B meteorological R&D satellite which was lost due to a malfunction in the booster guidance system less than a year before. It was designed to serve as a stabilized, earth-oriented platform for the testing of advanced systems for sensing and collecting meteorological data. It was lost due to a malfunction in the booster guidance system.
Thor-Agena was a series of orbital launch vehicles. The rockets used Thor first stages and Agena second stages. They are thus cousins of the more-famous Thor-Deltas, which founded the Delta rocket family.