The Soviet successes with its Sputnik satellites caused the United States to change its space plans.

VOA: special.2009.06.10

It means that the properties of the system, the properties that describe the system, don't change in time or in space.

它的意思是指，用以描述系统的性质，不随时间或空间改变。

麻省理工公开课 - 热力学与动力学课程节选

Cheng says that could change as Beijing sells space technology to more countries.

VOA: standard.2010.04.21