Venera 7, Soviet probe to Venus, launched 1970

Venera 7, a Soviet spacecraft and lander to Venus, was launched August 17, 1970.  The probe entered the Venusian atmosphere December 15 and the lander broke away from the bus.  The lander's parachute opened at an altitude of 60km and began the probe began to take tests, revealing the Venusian atmosphere to be 97% carbon dioxide.

The probe seemed to go silent upon impact, due to the parachute somehow failing during descent, but recording tapes kept going.  A few weeks later, scientists discovered about 23 minutes of weak signals.  They concluded the spacecraft had landed safely but harder than expected.  It bounced onto its side and the main antenna was pointed in the wrong direction to send strong signals to Earth.