OT. 38,000 +Satellites

I think they will all become debris before long. Maybe in my lifetime (I'm 81).

Low earth orbits decay pretty fast.

Stuff in synchronous orbit doesn't come down anything like as fast.

The worry is if someone carelessly causes a collision or deliberately destroys a satellite in some military test producing a lot of fragments big enough to get through the standard satellite protection layers.

Even a chip of paint at 11 miles a second is a formidable impact. If things go wrong a cascade failure is possible where each impact from the original event causes at least one more adding to the cloud of debris.

If this ever happened then we would have to use much more heavily armoured satellites and manned space flight would be too risky. Waiting for a while would allow most of the small stuff to fall to Earth.

Anything bigger than a spanner is routinely tracked these days by idle time on the BMEWS system or whatever has replaced it. Linked ground based telescopes with active optics can acquire remarkable pictures of objects in near Earth orbit. Declassified version here.

They do sometime do a small burn on the ISS to move it away from a predicted interaction with something in orbit getting too close. They last had to do it March 6th which is more recent than I had expected.

A lot of them will come down PDQ (and quicker still if this solar cycle turns out to be a highly active one). We have had two UK wide auroral displays this month which is very unusual and an active sun fluffs up the Earth's outer ionosphere speeding up low orbital decay massively.

That was a factor in the original Skylab being deorbited - strong solar activity caused it's orbit to decay much faster than had been anticipated.

Splitting a dead satellite at very low orbits (say 300 km) is a good thing, since the fragments have a large cross section area (and hence high air resistance) compared to fragment mass. Thus the fragments will decay much faster than an intact dead satellite.

Splitting an object at higher orbits is a bad thing, since it takes centuries, before the debris decays, increasing the risk of collisions.

People seem to be worried about the ISS astronaut safety. Boost the ISS to a higher orbit and the risk of collisions is greatly reduced. Of course this will reduce the resupply flight carrying capacity. The orbit can't be increased much above 1000 km due to the van Allen radiation belts.