60 years ago today, a small satellite ushered in the U.S. space program in a big way.

The U.S. is celebrating a milestone — 60 years in space today — with the anniversary of the launch of Explorer 1.

The small 6 foot, 9 inch, 31-pound satellite lifted off from launch complex 26A on Cape Canaveral at 10:48 p.m. Eastern Time (3:48 UT on February 1st). Explorer 1 used a four-stage Juno I rocket, a modified Army Jupiter-C rocket with an extra stage on top to reach orbit.

The Soviet Union had stunned the world just a few months prior with the launch of Sputnik 1 on October 4, 1957, closely followed by Sputnik 2 a month later. The launch of Explorer 1 finally put the United States in the space race.

The success of Explorer 1 followed a string of dramatic failures at the Cape in late 1957, including the explosion of the U.S. Naval Research Laboratory's Vanguard TV3 just seconds after liftoff on December 6, 1957. (The beleaguered Vanguard program finally got off the pad on March 17, 1958, and Vanguards 1, 2 and 3 are actually still in orbit around Earth today.) Explorer 1 reentered on March 31, 1970, after more than 58,000 orbits around Earth.

The launch required new innovations, among them the development of a fuel powerful enough to carry the rocket into orbit. Scientist Mary Sherman Morgan played a key role in the development of the Hydyne fuel used in the first stage of the Juno I rocket, George D. Morgan recounts in Rocket Girl.

Explorer 1 was the first mission to carry a scientific payload: a modified Geiger counter to detect cosmic rays, two micrometeorite detectors, and five temperature sensors. Legend has it that JPL engineer George Ludwig actually drove across the country to deliver the payload package to the Cape, stowed in the trunk of his 1956 Mercury sedan. Thanks to its cosmic-ray counter, Explorer 1 detected the Van Allen radiation belts surrounding Earth. The belts, named after James Van Allen (University of Iowa), who led the team that designed the instrument, were the first scientific discovery made in space.

Van Allen, Wernher von Braun, and William Pickering held a press conference in Washington D.C. shortly after the successful launch of Explorer 1, hoisting a model of the satellite over their heads in a now iconic image. Van Allen later became a key advocate for a civilian-led rather than a military-controlled space agency, Abigail Foerstner writes in her biography, The First Eight Billion Miles.

Amateur astronomers across the U.S. had been formally enlisted to keep an eye on satellites as part of Operation Moonwatch, a project that complemented professional tracking stations. Seasoned from the hunt for Sputnik 1, volunteers were at the ready to monitor Explorer 1 and the Vanguards. However, as W. Patrick McCray recounts in Keep Watching the Skies! The Story of Operation Moonwatch, the satellites were actually pretty faint and hard to find. “Hells Bells,” one amateur exclaimed, “couldn't they put a larger one up there?” By February 10th, some 200 teams worldwide had nabbed only 11 confirmed sightings of Explorer 1.

The U.S. space program grew quickly from those humble beginnings. NASA wasn't even “NASA” yet when Explorer 1 launched: the National Advisory Committee for Aeronautics (NACA) wouldn't become the National Aeronautics and Space Administration until designated as such by President Eisenhower later that year on October 1, 1958. But just over a decade later, humans would walk on the Moon.

What will the next 60 years in space bring? In 2018, watch for launches of the Parker Solar Probe billed as the first spacecraft to “touch” the Sun, the next-generation exoplanet-hunting Transiting Exoplanet Survey Satellite (TESS), the Mars Insight geodesy mission, and much more — all continuing the legacy that started 60 years ago with Explorer 1.

For more information on Explorer I, watch the NASA JPL lecture series: Explorer 1 and 60 Years in Space.