The International Space Station will soon be equipped with its very own same-day delivery service, for returning critical scientific samples back to Earth. The service will be provided by the Terrestrial Return Vehicle (TRV), a small, wingless capsule that can be loaded up with samples and ejected from the airlock, guaranteeing delivery back to Earth in under 24 hours. It's a bit like a gravity-powered courier service (and coincidentally, probably the most reliable courier service in the world).