Place a tax on every satellite or piece of space debris left in orbit as long as it is in orbit. Currently there are 45,000 objects orbiting earth. That would be a tax of $1,200 per year for each object. This would also provide an incentive for operators to not leave junk in orbit. Some enterprising company could make money collecting up the space junk. You would not have to deorbit it just collect it. If its not a separate trackable object it does not pay the tax. So the collector could charge the junk producer a fee for eliminating their object. Every time they grab a piece of junk the junk producer would pay for the removal. The removal service would need to be very efficient in choosing targets to remove to minimise the delta V required. Maybe even figure out how to use the difference in speed between the object being collected and its path to direct it to the next object to collect. Like a complex game of space billiards. The collection method would need to produce no debris. Probably the hardest part of the process to figure out. Anybody know how to build a space tractor beam?