Caption: Earth Check for Satellite--The antenna of the S-3a energetic particles satellite are spread during ground check prior to its mating to a Delta launch vehicle. Similar to Explorer XII but with improved engineering features, the S-3a space instrument is expected to make refined measurements of energetic particles and their relationship to the magnetic fields of earth and interplanetary space. When launched by NASA it is planned to fly an elliptical orbit--apogee: 54,050 miles; perigee: 184 miles--with a period of 31 hours.
The front and back of this photograph are pictured below:
