WASHINGTON, Sept 24 (Reuters) – NASA has chosen the aerospace startup Katalyst to help prevent a $500 million space observatory from plummeting into Earth’s atmosphere. The plan is to launch a special spacecraft that will nudge the observatory into a higher, more stable orbit. This urgent mission will also serve as a test of new satellite-docking technology, a capability central to ongoing technological competition in space between the United States and China. In an announcement on Wednesday,