NASA Identifies 1958 Vanguard 1 as Oldest Object Still Orbiting Earth
Updated
Updated · spacedaily.com · Jul 15
NASA Identifies 1958 Vanguard 1 as Oldest Object Still Orbiting Earth
3 articles · Updated · spacedaily.com · Jul 15
Summary
Vanguard 1 — a 16.3-centimeter, 1.5-kilogram satellite launched on March 17, 1958 — remains the oldest human-made object still in Earth orbit, NASA said.
Its survival stems from a high elliptical orbit, with a roughly 650-kilometer perigee and near-4,000-kilometer apogee, keeping it mostly above the denser atmosphere that pulled earlier satellites back down.
NASA estimates the spacecraft has an orbital lifetime of about 240 years from launch, implying re-entry around 2198 rather than the often-cited claim that it will stay aloft for several more centuries.
The satellite stopped transmitting in 1964, but radar and optical tracking still follow it, and its motion helped scientists refine models of Earth's shape, upper-atmosphere density and solar radiation pressure.
Vanguard 1 was also the first solar-powered satellite, making the silent sphere both a landmark of the early space age and, by modern standards, a piece of orbital debris.