Orbcomm satellites are low Earth orbit communications satellites, operated by the United States satellite communications company Orbcomm. As of July 2014^[update], 51 such satellites have orbited Earth, with 50 still continuing to do so.

Orbcomm-CDS (Concept or Capability Demonstration Satellites) are spacecraft which were launched to test equipment and communication techniques used by the other satellites. The first three CDS satellites, Orbcomm-X, CDS-1 and CDS-2, were launched before any operational satellites, in order to validate the systems to be used in the operational constellation.

Orbcomm-X, also known as Datacomm-X, was launched in 1991. It carried communications and GPS experiments. Initially, the spacecraft was reported healthy, but communication was lost after just one orbit.

CDS-3 was launched in 2008, along with the 5 Quick Launch satellites. It contained experiments for relaying signals from the United States Coast Guard Automatic Identification System through the satellite constellation. It was designated Orbcomm FM-29, having most of the communications payload from an unlaunched satellite. The avionics bus to that satellites later became TacSat-1.

Orbcomm-1 satellites make up most of the current Orbcomm constellation. 36 were built, of which 35 were launched, and one more, Orbcomm FM-29, was rebuilt as TacSat-1 for the United States military.

Orbcomm Quick Launch (QL) satellites are satellites which were intended to replenish the constellation. The first five such satellites were launched in 2008, with one more planned, but never launched. The satellites are based on the CDS-3 satellite, which was launched on the same rocket as the first five QL spacecraft. The sixth will be launched as a secondary payload to a Russian Government satellite, also on a Kosmos-3M. Orbcomm holds options for two further satellites. The satellites experienced a power system anomaly, and Orbcomm filed an insurance claim on the satellites for $50 million. Orbcomm reported in 2011 that the last remaining Quick Launch satellite had failed.

...
Wikipedia