ATDA, ATS, Alouette, Anna, Apollo, Ariel, Atlas-Score, Biosatellite, Castor and Pollux, Comsat, Cosmos, Courier, Diapason, Discoverer, ERS, Early Bird, Echo, Elektron, Explorer, GATV, Injun, Intelsat, Lofti, Luna, Lunar Orbiter, Lunik, Mariner, Mars probes, Mercury, Midas, Nimbus, OAO, OGO, OSO, Pageos, Pegasus, Pioneer, Proton, Ranger, Relay, Samos, San Marco, Secor, Siamese twins, Sputnik, Surveyor, Syncom, Telstar, Transit, Tweedledum and Tweedledee, Twin Stars, Vanguard, Viking, Voskhod, WRESAT, Zond, artificial satellites, exact mates, fraternal twins, identical twins, pair of twins, spacecraft, twins