It's predicted to have about 33 of these rocket engines.

预计将有大约 33 个这样的火箭发动机。

It's not new. NASA's RS-25 rocket engine has been around since the 1970s.

这不是什么新鲜事物。NASA的RS-25火箭引擎在20世纪70年代就已经出现。

Russia has delivered more than 120 rocket engines to the U.S. over the past 20-plus years.

在过去的20多年里，俄罗斯向美国交付了120多个火箭发动机。

Specific impulse is a method for measuring – in seconds –thrust and efficiency levels of rocket engines.

比冲是一种以秒为单位测量火箭发动机推力和效率水平的方法。

But experts looking at satellite imagery say that they believe that it was a rocket engine test.

但关注卫星图像的专家表示，他们认为朝鲜进行的是火箭发动机试验。

A carrier aircraft carries it high into the atmosphere and releases it before its rocket engine fires.

航空母舰将其高空带入大气层，并在火箭发动机点火之前将其释放。

They'll learn things such as how the rocket engine propels the craft and how insulation regulates equipment temperature.

他们还会学习诸如火箭发动机如何推动飞船，以及绝缘材料如何调节设备温度等知识。

The lander design concept incorporates next-generation parachutes and 12 rocket engines to slow the lander down as it descends.

这款着陆器设计概念融入了下一代降落伞和 12 台火箭引擎，以在下降过程中减缓着陆器的速度。

Russia has delivered more than 120 rocket engines to the U.S. over the past 20 years plus.

过去 20 多年里，俄罗斯已经向美国交付了 120 多个火箭发动机。

China has completed an important test of the rocket engine that will be used in its first Mars mission.

中国已完成火箭发动机的重要测试，该火箭发动机将用于首次火星任务。