Space junk is a serious problem.....

[Michael]

This is an interesting solution to at least part of the problem:

Scientists develop unique orbital cleaner

"Our model of a tug-collector proves a general possibility of solving the problem of space debris. A heavy satellite with low thrust engines, acting as a gravitational trap, is capable of capturing objects and eliminating them from the GSO," Vladimir Aslanov, Head of the Department of Theoretical Mechanics at Samara University, said.

The effect of gravity at the height of the GSO is relatively weak; therefore rather heavy objects create an area of their own attraction, the so-called Hill sphere. The optimal effect will be achieved with a collector weighing about 100 tonnes. Scientists believe that small asteroids could be used in the future.

If/when they decide to retire the international space station, I wonder it (or part of it) could be used in that capacity? I think it's more than 100 tons.

 

[Tanj]

I thought space was a vacuum. Isn't it self cleaning?

I think the bag needs emptying.

 

[Michael]

Here's another interesting idea:

https://satpass2019.wixsite.com/pass

The central drum will have a solid piece of an aerogel material placed inside. The targeted debris will collide with the areogel at a velocity sufficient enough to penetrate the material and become stuck.

The aerogel will be able to collect several pieces of debris at a time before reaching capacity. Once full capacity has been reached, the satellite will retrograde and de-orbit itself into Earth's atmosphere.