A Chinese Rocket Is Tumbling Back to Earth. Where Will It Land? The Long March 5B, the country’s largest rocket, is expected to come down sometime this weekend, but where and when are difficult to predict. China’s Long March 5B rocket lifting off from the Wenchang Spacecraft Launch Site on April 29.Credit...Matjaz Tancic/EPA, via Shutterstock May 8, 2021, 12:00 p.m. ET A piece of China’s largest rocket is tumbling back to Earth this weekend. No one really knows when or where it will land. On April 29, a Long March 5B launched a big piece of China’s next space station, Tiangong. Usually the large booster stages of rockets immediately drop back to Earth after they are jettisoned, but the 23-ton core stage of Long March 5B accompanied the space station segment all the way to orbit. Because of friction caused by the rocket rubbing against air at the top of the atmosphere, it has been losing altitude since and will soon make what is called “uncontrolled re-entry” back to Earth.