Satellites are used for GPS, weather forecasts, and more. Generally, satellites have to be small and tough enough to withstand launch. Repairing or upgrading them involves sending people to space—so they usually aren't made to be serviced. In-space robotic servicing could change this and open the door to other advances, like in-space assembly and manufacturing. But the technology is mostly unproven in space. Companies and U.S. agencies are hesitant to commit resources to it.