Ranger 4 was a spacecraft of the Ranger program designed to transmit pictures of the lunar surface to Earth stations during a period of 10 minutes of flight prior to crashing upon the Moon, to rough-land a seismometer capsule on the Moon, to collect gamma-ray data in flight, to study radar reflectivity of the lunar surface, and to continue testing of the Ranger program for the development of lunar and interplanetary spacecraft. An onboard computer failure caused a failure of the deployment of the solar panels and navigation systems; as a result, the spacecraft crashed on the far side of the Moon without returning any scientific data. It was the first spacecraft of the United States to reach another celestial body.