China is planning to send two new crews to its Tiangong space station in another busy year of human spaceflight. China's human spaceflight agency, CMSA, announced in early March that the country is planning to launch two crewed missions this year — Shenzhou 20 and Shenzhou 21 — along with a single Tianzhou cargo spacecraft to deliver fresh supplies and fuel to the Tiangong space station . The three-module Tiangong was completed in late 2022 and has been constantly occupied ever since, with three-person crews spending roughly six months in orbit before handing over to a new crew. China also…