This chapter describes extensions that enable the simulation of satellite networks in . In particular, these extensions enable to model the following: i) traditional geostationary ``bent-pipe'' satellites with multiple users per uplink/downlink and asymmetric links, ii) geostationary satellites with processing payloads (either regenerative payloads or full packet switching), and iii) polar orbiting LEO constellations such as Iridium and Teledesic. These satellite models are principally aimed at using to study networking aspects of satellite systems; in particular, MAC, link layer, routing, and transport protocols.