Spiny Norman said:
Believe it or not, according to the Index of Objects Launched into Outer Space maintained by the United Nations Office for Outer Space Affairs, there were 7,389 individual satellites orbiting our little planet at the end of April 2021 (others place the number closer to 6,500). This number is only set to increase over time, with some estimates coming in at around 990 satellites being added to the mix every single year.
If true, by about 2028, we can expect to see somewhere in the order of 15,000 satellites orbiting Earth. This includes the massive increase in satellites scheduled to be deployed by companies like SpaceX in their Starlink constellation. The rise of small CubeSats, microsats, nanosats, etc, may also increase the number several-fold over the coming decades or so.
Of the satellites in space, most are used for either commercial telecommunications or navigational purposes, with others used for scientific or military purposes.
The vast majority, around 60%, is actually defunct and have been left to their fate.
https://interestingengineering.com/oldest-undead-spacecraft
I’m surprised that it’s as small as 60%. Satellites tend to only last about ten years, if they work at all. And they’ve been put up in large numbers since the mid 1960s.
> Vanguard 1C, for example, was launched in 1958. All contact was lost with Vanguard 1 in 1964. It still orbits the Earth, and is officially the oldest piece of “space junk”.
Nice! What’s it’s perigee?
Perigee altitude 654 km
Apogee altitude 3,969 km
Inclination 34.25°
OK, that’s why it’s still up there. LEO is 160 to 1000 km. For a perigee of 400 km or less, a satellite will tend to fall back to Earth within two years.
> Lincoln Experimental Satellite 1, 1967.
Nice. “2,800 km circular orbit”. The LES series were military.
> in 2020, a self-described dead satellite finder, Scott Tilley, found that the telemetry beacon for LES-5 (launched 1967, in geostationary graveyard orbit) was still transmitting at 236.75 MHz. Whether or not you consider this as a “working” satellite, or not, it is fascinating to find such early space tech still working.
:-)
> the Transit 5B-5 satellite. It was part of the Transit/Navsat navigational satellite program. First launched into orbit in 1964, it acted as a telemetry transmitter and can still occasionally transmit at 136.650 MHz when it’s passing through sunlight.
> AMSAT-OSCAR 7, 1974
Read the link, it has a fascinating history. eg. Coming back to life in 2002. Use by the Polish Solidarity movement in 1982.
> Another old piece of kit in space that might just work is the British-made satellite called Prospero. The satellite was launched from Australia in 1971 – the first and only UK spacecraft to be launched on a British-built rocket, the Black Arrow.
I thought I recognised the name.
> Perhaps the oldest still functional, spacecraft are Calsphere 1 and 2. Launched in 1964.
US military.
> Yet another old piece of tech in space that still works is the Laser Geometric Environmental Observation Survey 1, LAGEOS-1 for short. Designed and launched by NASA in 1976, it is one of a pair of scientific research satellites. LAGEOS-1 is still in use to this day.
That looks remarkably like an Australian owned satellite, made in Russia. Cube corner reflectors inset into a spherical shell.
> International Sun-Earth Explorer 3 (ISEE-3). Launched in 1978, it was the first spacecraft to be placed in a halo orbit at the L1 Earth-Sun Lagrange point. Two-way communication was reestablished with the probe in 2014 but then lost.
