Answer: ogo

AnswerCrossword Clue
OGOObservatory in the skies.
OGO"Observatory" satellite.
OGOU.S. satellite.
OGOSpace initials
OGOSky observatory: Abbr.
OGOU.S. satellite
OGORelative of Explorer
OGOU.S. space observatory
OGOU.S. scientific satellite of the 60's
OGOU.S. satellite of the '60s