China sent three astronauts to its permanently inhabited Tiangong space station on Thursday in its 15th crewed spaceflight and 20th overall in its Shenzhou program, which started more than three decades ago.

China has launched three astronauts to replace the crew on the Chinese Tiangong space station. The Shenzhou 20 spaceship took off as planned atop China’s workhorse Long March 2F rocket at 5:17 p.m. local time (0917 GMT).