Communications via satellite introduces a number of technical problems for mobile networks and applications. Satellite links have fundamentally different properties from terrestrial wired or wireless networks. These differences have far-reaching effects on many satellite communication issues. This text's emphasis is on data networking, internetworking and distributed computing issues. The material surveys recent work in the area of satellite networks, introduces certain state-of-the-art technologies, and presents recent research results in these areas. A variety of issues involving applications, network architecture, medium access controls, multicast routing, asymmetric routing, transport protocols, TCP performance enhancement techniques, data broadcast, and information disseminations, are addressed.