Years of busy launches have left a messy belt of junk above the red planet: retired solar panels, bent satellite dishes and cargo plates that came loose on the way down. The next supply ship cannot dock until the orbit is clear, so pixel Elon climbs aboard a small cleanup shuttle with a glowing tow-sphere and a pair of tiny lasers. Mission control calls the job Orbit Sweeper.
Every panel the sphere knocks loose drifts safely down to burn up in the thin Martian air, and now and then a spare fuel cell floats free, worth catching on the shuttle. The junk is packed in tight walls, and each new wall comes in a little faster than the last. Let the sphere slip past the shuttle three times and the shift is over. How many walls can pixel Elon sweep before the supply ship arrives?
