10/08/2026
DYK: On 4 October 1957, the Soviet Union launched Sputnik 1, the first human-made satellite to orbit the Earth. The very next day, on its first day of operation, Lincoln Laboratory's newly built Millstone Hill radar detected the satellite. This early success launched a long list of achievements for the radar, which the Laboratory had built as a prototype for the Ballistic Missile Early Warning System, surveillance network designed to detect a large-scale missile attack.
Herbert Weiss, leader of Group 31, Special Radar Systems, designed the Millstone Hill radar, and staff from Divisions 1, 2, 3, 4, and 7, along with roughly one hundred industrial partners, contributed to its construction. The Laboratory built the radar on Millstone Hill, a 1100-acre site in Westford, Massachusetts, owned by Massachusetts Institute of Technology (MIT). The original system featured a large 84 foot dish antenna and a powerful transmitter capable of tracking objects at long range, along with a solid-state computer to calculate trajectories.
Following its detection of Sputnik 1, the Millstone Hill radar continued to break new ground. The following year, it became the first radar to track a satellite (Sputnik 2) from horizon to horizon. This was made possible by a tracking system Lincoln Laboratory developed to automatically follow fast-moving objects across the sky. The radar later became the first sensor in the U.S. Air Force's Project Space Track, the nation's first formal effort to track satellites.
Researchers originally used the Millstone Hill radar for ionospheric research and lunar and planetary detection. Today, the radar tracks satellites and space debris as part of the United States Space Surveillance Network, contributing roughly 20,000 satellite observations each year, and provides coverage for almost all deep-space launches. It is also used for atmospheric science investigations.
