DSIF 1 (Mobile Near point of 10-ft antenna Fast tracking Tracking injection of 25-w, 890-mc for acquisition Station) spacecraft into transmitter of spacecraft Earth-escape trajectory Goldstone: California Pioneer Site 85-ft Reception of (DSIF 2) polar-mount telemetry antenna; Tracking Cassegrain spacecraft feed; maser and parametric amplifier Echo Site 85-ft Transmission of (DSIF 3) polar-mount commands antenna; Tracking parametric spacecraft amplifier Stand-by 10-kw, 890-mc reception transmitter Venus Site 85-ft Advanced radar radar-type astronomy antenna Communications research DSIF 4 Woomera, 85-ft Reception of Australia polar-mount telemetry antenna; Tracking parametric spacecraft amplifier DSIF 5 Johannesburg, 85-ft Reception of South Africa polar-mount telemetry antenna; Tracking parametric spacecraft amplifier Transmission of 10-kw, 890-mc commands transmitter The stations are equipped with receiving and tracking instruments so sensitive that engineers estimate that they can detect radio-frequency energy equivalent to that radiated by a 1-watt light bulb at a distance of approximately 75 to 80 million miles. Such energy received at the antenna would measure about 0.00000000000000000002 watt (2 × 10⁻²⁰). The amount of power received at the antenna during Mariner’s encounter with Venus has been calculated at about 0.000000000000000001 of a watt (1 × 10⁻¹⁸). If a 100 percent efficient storage battery were charged with this amount of energy for some 30 billion years, the battery would then have stored enough energy to light an ordinary 1-watt flashlight bulb for about 1 second only.