To get you started thinking about space junk:
NASA space scientist James Mason and his team of NASA Ames Research Center and the University of Space Research Association in California have recently proposed a new theory to deal with the pieces of debris in the low Earth orbit (LEO) that are colliding with each other to create more pieces. They discovered a possible method of using a laser beam to change the velocity of the junk’s orbit by focusing the beam on it to slow it down and change its orbit. This can stop the debris from colliding with communications satellites or the International Space Station.
The scientists mention that continual evaluation of the chances of a collision between two space debris of 5 cm or more in diameter would be needed using radar data from the US Space Surveillance Network. The junks on the path of collision would then be tracked by an optical telescope. One of them will be locked on and the release of the laser beam will occur. Just by using 5-10 kilowatts commercially available lasers mounted on 1.5 meter telescopes placed close to the poles, the risk of more than half of potential space junk collisions could be significantly reduced. The total cost of the scheme would be no more than $10m, making it a much cheaper alternative than other ideas such as direct removal of space debris.
The new paper could give insight into how we can avoid the Kessler syndrome, where if more and more space junk are be created and colliding with each other, the generations of debris could ultimately render space exploration and satellite launches impossible. This prediction was done by a NASA scientist in 1978 and new solutions have been presented since then a lot with multiple complications and high price tags. Moreover, other countries involved in space exploration saw the proposed methods as threats to their functional satellites.
Although a feasible theory, the scientists speculate whether this method could actually do the trick remains a topic of debate. Team member William Marshall points out that there are a lot of uncertainties in the model and space-debris models need to be run to be certain that the theory will be effective in the long term.