OTD in Space – April 23: Ranger 4 Launches on Failed Moon Mission

On April 23, 1962, NASA launched the Ranger 4 mission to the moon. [‘On This Day in Space’ Video Series on Space.com]

After the first three Ranger missions failed, NASA was really happy with the successful launch of Ranger 4. But the fun didn't last long. After a picture-perfect launch on an Atlas-Agena rocket, Ranger 4 stopped transmitting telemetry data. Tracking stations picked up an empty signal from its radio transponder. Without that telemetry, mission control couldn't confirm that the spacecraft had deployed its solar panels and high-gain antenna. When they tried to send commands to its on-board computers, they got no response. They could tell from fluctuations in the radio signal that Ranger 4 had not stabilized itself like it was supposed to. Instead, it was tumbling around in space with its solar panels still tucked in to its sides. While the mission was essentially a failure at that point, Ranger 4 did become the first American spacecraft to reach the moon. It crashed into the moon's far side three days after the launch.