March 21 in Universe History: Space Missions, Satellites and Exploration

March 21 has produced notable milestones in space exploration, planetary science, orbital operations, launch systems, and deep-space engineering. Below is a curated chronological selection of universe-related events connected to this date.

1963

On 21 March 1963, transmitters aboard the Soviet Mars 1 probe fell silent. The final radio contact occurred when the craft was about 106 million km from Earth, ending communications during cruise and leaving it to proceed toward its planned Mars flyby without further telemetry, after earlier relays had returned measurements of interplanetary conditions between Earth and Mars.

1965

On 21 March 1965, Ranger 9 launched from Cape Canaveral on an Atlas-Agena vehicle, targeting a lunar impact at Alphonsus. During descent it transmitted live TV images broadcast to the public, closing the Ranger program with high-resolution photography and providing geological context for lunar landing analysis and mission planning by later explorers while validating guidance and imaging systems.

1999

On 21 March 1999, an International Launch Services Proton rocket lifted off from Baikonur and carried the AsiaSat 3S commercial communications satellite into geosynchronous transfer orbit, demonstrating late-1990s heavy-lift commercial launch operations and enabling additional regional telecom capacity after on-orbit raising, testing, and handover to the satellite operator.