Sputnik 1 (USSR, 1957)

On October 4, 1957, the Soviet Union launched a polished aluminum sphere 58 cm across and 83 kg in weight into low Earth orbit, transmitting a simple radio beep audible to amateur receivers worldwide. Sputnik 1 was in orbit for only 92 days before burning up on re-entry, but its consequences were enormous and permanent. It proved that orbital spaceflight was achievable, triggered the United States' creation of NASA in 1958, accelerated the entire Space Race, and demonstrated that objects in Earth orbit could be used for communications and reconnaissance. Every satellite above your head today — GPS, weather, internet — is a direct descendant of those first 92 days of beeping.