Nuclear bombs. That’s the go-to answer for incoming space objects like asteroids(小行星) and comets, as far as Hollywood is concerned. Movies like Deep Impact and Armageddon rely on nuclear weapons, delivered by stars like Bruce Willis, to save the world and deliver the drama.

But planetary defense experts say in reality, if astronomers spotted a dangerous incoming space rock, the safest and best answer might be something unnoticeable, like simply pushing it off course by crashing it with a small spacecraft.

That’s just what NASA did on Monday evening, when a spacecraft headed direct into an asteroid called Dimorphos, which is around 7 million miles away and poses no threat to Earth. It’s about 525 feet across and orbits another larger asteroid.

In images streamed as the impact neared, the egg-shaped asteroid grew in size from a little spot on screen to have its full rocky surface come quickly into focus before the signal went dead as the spacecraft hit right on target.

Events happened exactly as engineers had planned, they said, with nothing going wrong. “As far as we can tell, our first planetary defense test was a success,” said Elena Adams, the mission systems engineer, who added that scientists looked on with “both terror and joy” as the spacecraft neared its final destination.

The impact was the peak of NASA’s Double Asteroid Redirection Test (DART), a 7-year and more than $300 million effort which launched a space vehicle in November of 2021 to perform humanity’s first ever test of planetary defense technology. It will be about two months, scientists said, before they will be able to determine if the impact was enough to drive the asteroid slightly off

course, probably shortening its original orbit.

NASA plans to launch an asteroid-hunting space telescope named NEO Surveyor in 2026. “We’ve tracked lots of space rocks, especially the larger ones that could cause extinction-level events. Thankfully, none currently threaten Earth. But many asteroids the size of Dimorphos haven’t yet   been discovered, and those could potentially take out a city if they came crashing down.” explains Lindley Johnson, NASA’s Planetary Defense Officer.

【小题1】What’s the function of Paragraph 1?

A．It adds some background information.

B．It introduces the topic of the passage.

C．It presents author’s main idea.

D．It serves as an abstract of the essay.

【小题2】How did scientists know the spacecraft hit the asteroid successfully?

A．They monitored the spacecraft with satellites in space.

B．They recorded the whole process with a telescope.

C．The little spot on the screen suddenly disappeared.

D．The signal from the spacecraft was lost as it hit the target.

【小题3】What is the purpose of launching the spacecraft?

A．To test technology for defending Earth.

B．To end the asteroid’s threat to Earth.

C．To search for evidence of alien life.

D．To show engineers’ terror and joy.

【小题4】Which statement will Lindley Johnson probably agree with?

A．NASA’s plan will definitely a success.

B．Larger asteroids will no longer threaten Earth.

C．NEO Surveyor is aimed to track smaller asteroids.

D．Asteroids are equally destructive whatever the size.