在太空自由飞翔
2020 February 9 To Fly Free in Space Image Credit: NASA, STS-41B Explanation: What would it be like to fly free in space? At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was living the dream — floating farther out than anyone had ever been before. Guided by a Manned Maneuvering Unit (MMU), astronaut McCandles...