Once the shuttle is retired this year, the only way for the United States to get astronauts into orbit will be on Russian Soyuz rockets.

VOA: special.2010.04.28

So, what he did was kind of impose a quantum mechanical model, not a full one, just the idea that those energy levels were quantized on to the classical picture of an atom that has a discreet orbit.

还不是完整的,只是这些能级，是量子化的概念，作用到原子有分立轨道的经典原子模型上,当他做了一些计算后,他得到有个半径,他算出来。

麻省理工公开课 - 化学原理课程节选

He had flown on Apollo Eight, the first flight to orbit the moon.

VOA: special.2009.07.22

On the sixty-second orbit, the astronauts prepared to return to Earth.

VOA: special.2009.06.24

President Barack Obama is calling on private companies, not the national space agency, to carry astronauts into orbit.

VOA: standard.2010.04.21