Vanguard 1
Launched in March 1958 and silent since 1964, Vanguard 1 is still going round. Everything humanity put into space before it has burned up or been brought down — this grapefruit-sized sphere outlasted all of it, and will outlast us too.
What makes Vanguard 1 different
Older than everything else up there
Sputnik 1 and 2 and Explorer 1 all launched before it and all re-entered decades ago. Vanguard 1 is the oldest human-made object still in orbit, and has been for more than half a century.
It is high enough not to fall
Its ellipse runs from about 660 km out to 3,800 km. There is almost no atmosphere that high, so the drag that pulls the ISS down by a hundred metres a day barely touches it. Estimates put its remaining life in the hundreds of years.
The first satellite to run on sunlight
It carried six small solar cells alongside a battery-powered transmitter. The battery died within months; the solar-powered transmitter kept going until 1964. Every solar panel in orbit today descends from that experiment.
It measured the shape of the Earth
Tracking small deviations in its orbit revealed that Earth is very slightly pear-shaped rather than a clean ellipsoid — a result from a satellite carrying no instrument beyond a radio.
Vanguard 1 was a 1.47 kg aluminium sphere about 16 cm across, and Nikita Khrushchev reportedly dismissed it as the grapefruit satellite. It was the fourth object ever placed in orbit and the second American one, launched during the scramble that followed Sputnik. The mockery has aged badly: it is still there, and the orbit it was placed in is why. Its perigee sits far above the thin upper atmosphere that gradually drags low satellites down, so it has quietly kept going for over sixty-five years while everything from its era came home. The position above is propagated from a current element set — the same maths applied to the newest Starlink, still tracking a satellite launched during the Eisenhower administration.
Frequently asked questions
Is Vanguard 1 still working?
No. Its transmitters fell silent in 1964. It is a passive object now, tracked by radar rather than by radio.
Why has it not burned up?
Its orbit is high — from roughly 660 km at the lowest point out to 3,800 km. At those altitudes atmospheric drag is negligible compared with low orbit.
How much longer will it stay up?
Estimates run to several hundred years, though solar activity affects the upper atmosphere and makes any figure approximate.
What was the oldest satellite before this one?
Sputnik 1 reached orbit first in 1957 but re-entered within months. Vanguard 1 has been the oldest object in orbit since Explorer 1 came down in 1970.