As she punched the six-button triggering sequence, the Alyut crossed those final kilometers and emitted the flare, a sustained burst of radio energy at 1420 mega-hertz, broadcast frequency of the hydrogen atom. Tsiolkovsky’s radio telescope was tracking, relaying the signal to geosynchronous comsats that bounced it down to stations in the southern Urals and New South Wales. For 3.8 seconds the Alyut’s radio-image was obscured by the afterimage of the flare.