SATNET

Trans-Atlantic link to NORSAR and University College London in September 1973 (prior to SATNET)
SATNET, from the Peter T. Kirstein report to DARPA, 1977
First Internet demonstration, linking the ARPANET, SATNET, and PRNET on November 22, 1977
SATNET diagram, mid 1979

SATNET, also known as the Atlantic Packet Satellite Network, was an early satellite network that formed an initial segment of the Internet. It was implemented by BBN Technologies under the direction of ARPA.

The first heterogeneous computer network was implemented in 1973, connecting the ARPANET to University College London. This evolved into SATNET. The first Transmission Control Program demonstration, linking SATNET, the ARPANET, and PRNET took place on November 22, 1977.