The article discusses the looming risk of too many satellites and debris in space, following a 2009 collision between the dead bird and the live bird that left over 1,800 pieces of debris at least 10 cm (4 in.) or larger. The collision could result in a chain reaction known as the Kessler syndrome, which could potentially wipe out entire flocks of spacecraft in that orbital band. According to NASA’s Orbital Debris Program Office, there are over 25,000 objects larger than 10 cm currently orbiting Earth, most of them satellites. However, this is only a tiny fraction of the problem. The International Space Station (ISS), the Hubble Space Telescope, and China's Tiangong space station are among the most vulnerable objects in that band. The article discusses how to prevent future collisions in space.