America’s second satellite, Vanguard 1, was launched into space on March 17, 1958. And though it only blasted off some six months after the Soviet’s Sputnik satellite, Vanguard 1 still remains in orbit — more than 60 years later. This makes it Earth’s longest-orbiting artificial satellite, as well as the oldest human-made object still in space.
Part of the key to Vanguard’s longevity is that it is truly puny. Vanguard is a metal sphere that weighs just 3 pounds (1.5 kilograms) and stretches 6.5 inches (16.5 centimeters) across, making it smaller than a basketball — or, as Soviet leader Nikita Khrushchev dubbed it, “the grapefruit satellite.” Despite its minuscule measurements, Vanguard was groundbreaking. It was the first solar-powered spacecraft, drawing its energy from six matchbox-sized panels.
The U.S. Naval Research Laboratory was tasked with building the spacecraft as part of the science program for the International Geophysical Year from 1957 to 1958, and in some ways, Vanguard was also a precursor effort to NASA. A number of Navy researchers who worked on it ended up joining NASA when the space agency was first formed in 1958, creating the core of Goddard Space Flight Center. These scientists designed Project Vanguard as an experiment to study how the environment of space affects satellites. They observed how its trajectory strayed from their predictions, using that information to refine their understanding of the properties of Earth’s upper atmosphere. Vanguard was also meant to test the launch abilities of a three-stage launch vehicle, which was (uninspiringly) also named Vanguard. And that’s why it has such a distant, long-term orbit.
The first two satellites successfully launched into orbit — Sputnik 1 and Sputnik 2 — were sent on smaller rockets. That meant they didn’t get as far from Earth’s surface, causing them to plummet back to Earth within the first year. The third (and America’s first) satellite, Explorer 1, stayed aloft a bit longer, returning to Earth after 12 years.
But with Vanguard 1, its high orbit led scientists to suspect it could stay in the void of space for roughly 2,000 years. Eventually the researchers learned that space has more drag than they expected, which forced them to revise Vanguard’s predicted orbital lifespan to about 240 years.
