我们经常在各种媒体中了解到航天器的发射有一定的“发射窗口”。那什么是航天器的发射窗口呢? 用运载火箭发射航天器,不是任何时候都可以进行的,要选择特定的年、月、日和时刻。比如,哈雷彗星以76年为周期回归, We often know in various media that there is a certain “emission window” for the launch of spacecraft. What is the launch window of a spacecraft? Launching a spacecraft with a launch vehicle can not be done at any time. It is necessary to select a specific year, month, day and time. For example, Halley’s Comet is returning on a 76-year cycle.