{"type":"programs","slug":"1958-explorer-1","title":"Explorer 1","url":"https://disclosdex.com/programs/1958-explorer-1","description":"First American satellite that discovered the Van Allen radiation belts and marked the beginning of US space science exploration","date":"1958-01-31T00:00:00.000Z","tags":["Satellite"],"updated":"2025-06-13T13:26:43.000Z","connectionCount":0,"content":{"markdown":"## Origins and Context\n\nThe United States launched Explorer 1 on January 31, 1958, in response to the Soviet Union's Sputnik launches.[^1] The Army Ballistic Missile Agency and Jet Propulsion Laboratory developed the satellite in less than 90 days after President Eisenhower's directive.[^2]\n\n## Program Structure\n\nJPL designed and built the 30.8-pound satellite while von Braun's team modified a Jupiter-C rocket (designated Juno I) for the launch.[^3] The spacecraft carried instruments including a cosmic ray detector, micrometeorite sensors, and temperature probes.[^4]\n\n## Legacy\n\nExplorer 1's cosmic ray detector, designed by James Van Allen, led to the discovery of radiation belts around Earth trapped by the planet's magnetic field.[^5] The satellite transmitted data until May 23, 1958, and remained in orbit until March 31, 1970, completing over 58,000 orbits.[^6]\n\n[^1]: [NASA JPL - Explorer 1](https://www.jpl.nasa.gov/missions/explorer-1)\n\n[^2]: [NASA History - Explorer 1 Overview](https://www.nasa.gov/history/explorer-1-overview/)\n\n[^3]: [NASA Science - About Explorer 1](https://science.nasa.gov/mission/explorer-1/about)\n\n[^4]: [NASA - Explorer 1](https://www.nasa.gov/mission/explorer-1/)\n\n[^5]: [NASA History - Explorer 1 Overview](https://www.nasa.gov/history/explorer-1-overview/)\n\n[^6]: [NASA Science - About Explorer 1](https://science.nasa.gov/mission/explorer-1/about)","readingTime":"1 min read"},"relatedRecords":[],"citation":{"canonicalUrl":"https://disclosdex.com/programs/1958-explorer-1","title":"Explorer 1","publisher":"Disclosdex","retrievedFrom":"https://disclosdex.com/api/v1/programs/1958-explorer-1","license":"CC-BY-4.0"}}