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 in-coming space rock, the safest and best answer might be something more subtle, 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 straight into anasteroid 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 (传输) as the crash 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 craft 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 crash was the peak of NASA’s Double Asteroid Redirection Test (DART), a 7-yearand 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 crash 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.

Countries around the world are spending plenty of dollars and lots of time on various space tasks.     20     Instead, we should feed the world’s poor and find immediate solutions to other problems. However, others feel this is a shallow view which fails to realize how exploring space helps us.

    21     It has directly resulted in the many satellites (that now move around the earth. A number of the satellites record data on land and weather patterns.     22     After careful analysis, the scientists can provide useful recommendations and advice for farmers.

Space exploration has already enhanced technological improvements that benefit us all. High-end products around the world are made to a higher standard. Today space technologies are widely used in all kinds of industries.     23    

Sending astronauts (宇航员) into space has helped people think about the world’s problems and find ways to solve them. Our planet’s resources are limited. In order to provide for the rapidly increasing population, scientists are trying to find other planets that could one day be our new home.     24     In the future, humans may live on both planets.

Exploring space benefits us so much. So it should be continued so as to provide new and better solutions to people’s short-term and long-term problems.

Aeronautics (航空学) specialists from the University of South Australia spent months studying the dragonfly’s flight, creating 3D models from digital images,     25     (build) a winged drone (无人机). Study leader Javaan Chahl believes that winged drones     26    (base) on the dragonfly’s shape and movement will simply be     27    (flexible) and energy efficient, compared to the previous ones.

Chahl’s team used a special photography technique to classify     28     wing shapes of 75 different dragonfly species from museum collections. Their wings are long, light and hard. Plus, their long bodies give them excellent stability and balance, making it possible for winged drones to deliver awkward loads     29     carry out long observation missions.

Investigating the way that dragonflies remain stable during flight actually     30    (reveal) the techniques they use to get themselves out of tricky situations. Dragonflies are found to be able to perform upside-down backflips to regain balance and normal flight, when they find themselves upside down mid-air. This special skill can even     31    (perform) while dragonflies are unconscious, meaning it is a passive stability mechanism similar in concept     32     planes that are designed to sail to     33     (safe) with their engines turned off. Engineers are looking to copy dragonfly wings to create safer ones,     34     can right themselves.