The rocket is long and slender, and fatter on top because its second stage is thicker than its solid rocket motor-powered first stage.

火箭又长又细，上部有点粗，因为它的第二级比固体燃料火箭发动机驱动的第一级要厚。

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The ignition of the solid rocket motor (SRM) is a very complex physical and chemistry process, which is composed of three component phases: ignition delay, flame spreading and chamber filling.

固体火箭发动机的点火是一个十分复杂的物理化学过程，包括三个阶段：点火延迟、火焰传播和燃烧室气体充填。

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Solid rocket motor design is a complicated systems engineering.

固体火箭发动机设计是一项复杂的系统工程。

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Space debris made news on March twelfth when a part of an old rocket motor about ten centimeters in size threatened the International Space Station.

VOA: special.2009.04.01

SpaceShip Two will use its hybrid rocket motor to propel itself into space.

FORBES: Out Of This World: Space, The Final Frontier

The term hybrid is used because this type of rocket motor uses neither all-liquid fuel nor all-solid fuel, but a combination of both.

BBC: Hybrid success for British rocket

Dr Baker reckons that costs can be cut if the launch rocket uses the satellite's guidance computer instead of having its own, and if the satellite's built-in rocket motor is bolstered to do the work now performed by a launch rocket's upper stage.

ECONOMIST: Space