Here's a quiz question: what do using road navigation systems, keeping time consistent around the world and having accurate stock exchange data have in common? The answer is that they all depend on working satellites. But an increasing amount of debris polluting space is now posing a risk to all those services. So one Japanese firm, Astroscale, has been working on ways to clean up space junk. Its founder and chief executive Nobu Okada explains.
Video by Adam Tyrrell and Pamela Parker