Make Your Career Soar

Forty-seven years ago this week, USAF’s Space and Missile Systems Organization (SAMSO) successfully orbited an octet of satellites on the first mission of the Initial Defense Communication Satellite Program (IDCSP).  This feat marked the beginning of America’s first operational geosynchronous orbital communications system.

The Initial Defense Communications Satellite Program (IDCSP) was the world’s first military satellite communications system.  It consisted of clusters of small, polygonal satellites deployed in near-geosynchronous earth orbit.  IDCSP satellites transmitted both voice and photographic data vital to U.S. military commanders.

Each IDCSP satellite external configuration was a 26 sided polygon measuring 34-inches in diameter.  With a mass of roughly 100 lbs, the communication satellite was spin-stabilized and its external surface was almost completely covered with solar cells.  With the onus on simplicity, the type employed neither internal storage batteries nor an active attitude control system.

During a typical IDCSP mission, up to eight (8) satellites were placed into near-geosynchronous earth orbit by a single launch vehicle.  Each satellite was dispensed individually.  Since their orbits were not quite synchronous, IDCSP satellites drifted west to east up to 30 degrees per day.  This feature helped ensure that at least one satellite was always visible to a ground station in the event that an adjacent IDCSP satellite became non-op.

On Thursday, 16 June 16 1966, an USAF Titan IIIC launch vehicle lifted-off from Cape Canaveral’s LC-41 at 1400 UTC.  The multi-staged booster successfully placed seven (7) IDCSP satellites and a single gravity-gradient experimental satellite into equatorial orbit at an altitude of approximately 18,354 nm.  Each of the constituent satellites functioned well and successfully passed a series of on-orbit preliminary tests.  The IDCSP system then declared “operational” in short order.

Between June of 1966 and June of 1968, a total of twenty-six (26) IDCSP satellites were orbited by USAF Titan IIIC launch vehicles.  A quartet of launches was required to accomplish such.  While the IDCSP system was experimental in nature, it in fact provided the United States with a viable space-based, global communication network for over a decade.

IDCSP satellites transmitted reconn photographs and other intelligence data throughout  the Vietnam War.   At the point of IDCSP initial operating capability (IOC), the system was redesignated as the Defense Satellite Communications System I (DSCS I).  Enhanced-capability variants, DSCS II and DSCS III, came in succeeding years (the later serving into the 21st century).


Posted in Aerospace, History

Leave a Reply

Your email address will not be published. Required fields are marked *