Oldest piece of space junk still in orbit

The oldest piece of space junk still in orbit is the third stage of a US-made Vanguard rocket that was used to place the Vanguard 1 satellite in orbit on 17 March 1958. After separating from the grapefruit-sized satellite, the Vanguard third-stage booster settled into an orbit with a perigee (lowest point) of 651 km and an apogee (highest point) of 4,226 km, where it remains to this day as object 1958-002A. It completes an orbit of Earth every 137 days.

The Vanguard rocket was developed to launch the first artificial satellite into orbit. However, delays and technical problems (including two attempted launches that ended in fiery disaster on live television) meant that the Soviet Union was able to claim this record first with their Sputnik 1 satellite. Uncertainty about the reliability of the Vanguard rocket meant that the first US satellite ended up being Explorer-1, which launched on a modified Redstone ICBM about six weeks earlier.