Which of these celestial objects is called a minor planet? Pluto, Asteroid, Moon, Sirius. Asteroids are also called minor planets, objects that orbit the sun but are neither planets nor comets.
NASA and the European Space Agency are teaming up to see if they can throw an asteroid off course. In three years, a certain asteroid and its moon are expected to pass between Earth and Mars. Scientists are hoping to smash a spacecraft into the smaller rock and then take measurements to see if the collision was able to change the moons orbit around the asteroid.
OK, why? They're hoping to find out whether it's possible to redirect an asteroid if one is on a collision course with Earth someday. The mission is estimated to cost NASA around $314 million, but it's not the space agency's only mission that involves an asteroid. The Osiris-Rex mission, which sounds like a dinosaur, is an $800 million effort to bring a sample of an asteroid back to Earth.
美国国家航空航天局（NASA）和欧洲航天局将联手合作，看看能否使一颗小行星偏离轨道 。预计一颗小行星及其卫星将在三年后经过地球和火星之间 。科学家希望用一艘宇宙飞船撞击这块较小的岩石，随后测量这次撞击能否改变环绕这颗小行星飞行的卫星轨道 。
问题是，为什么要这么做？他们希望能确定，如果一颗小行星处于将与地球相撞的轨道上，那是否有可能对其重新定向 。据估计，NASA将在这项任务上花费约3.14亿美元，但这不是NASA唯一一项涉及小行星的任务 。源光谱释义资源安全风化层辨认探测器（简称Osiris-Rex）这项名字听起来像恐龙的任务，计划斥资8亿美元将一颗小行星的样本带回地球 。
1. team up (与…)组队；(与…)协作；
Recently a friend suggested that we team up for a working holiday in Europe in the summer.
2. be expected to do sth. 预期；预料；
Sales to the British forces ar e expected to drop off.
3. be able to do sth. 可以…的，能够…的；
We were only able to make a rough estimate of how much fuel would be required.
4. find out (尤指特意通过努力)发现，找出，查明；
An investigation is underway to find out how the disaster happened.