3 . There are nearly 2,800 working satellites in space, which we depend on for technology we use every day, such as video calls, online maps, satellite TV, and weather tracking. Scientists use them to study space and learn more about our planet.

But there are many other satellites in orbit (轨道) that are no longer working. They're among the objects cluttering (使杂乱) up space. Some of these eventually fall back toward Earth, either landing or burning up in the atmosphere. But much of this space junk (垃圾) circles Earth for years. Space junk is a problem. Debris (残骸)   floating around Earth puts technology and future space tasks at risk. Experts are working on ways to solve it.

Orbital debris, a type of space junk, is any human-made object that has slopped working but continues to float around the Earth. This includes satellites that are no longer used and pieces of spacecraft, such as rocket stages. It has been a large problem since the 1960s.

Space junk also includes broken pieces of objects. These occur when satellites hit against things. They also result from an object crashing into an old rocket stage that still contains fuel, causing an explosion (爆炸) . There have been more than 250 space explosions since the 1960s. These tiny broken pieces can damage working satellites, which can affect research in space.

Companies all over the world are working to clean up the area surrounding our planet. A company based in Japan will test the method of using magnets (磁石) to collect space debris. Another mission is led by a company based in Switzerland. It plans to carry out a debris-removal spacecraft in 2025. The craft will get hold of a piece of an old rocket, slow it down, and move it back to Earth. Eventually, the debris will burn out like a shooting star.

Governments are trying to help too. Some are updating their country's space guidelines to limit the amount of debris created. Space is so large that the problem won't be solved by a single organization or a single country. We have to work on this together.

1. What is the biggest harm that space junk does to human beings?

A．It will fall back toward the Earth.	B．It circles the Earth for years.
C．It puts other space objects in danger.	D．It will burn up in the atmosphere.

2. How will the Swiss company clean up the Earth orbit?

A．By making the orbital debris fall back to Earth.	B．By putting the pieces all together.
C．By collecting space junk with magnets.	D．By sending space junk into deep space.

3. What does the author suggest on cleaning up space junk?

A．Strict laws.	B．Global efforts.
C．Stopping in space exploration.	D．Setting up professional organizations.

4. What does the text mainly talk about?

A．Earth and its satellites.	B．The problem of space junk.
C．Ways of cleaning up space junk.	D．The various uses of man-made satellites.

4 . The company SpaceX has already launched hundreds of its Star-link satellites, with plans to put as many as 42,000 of them in Earth orbit. Its goal is to provide high-speed Internet to billions of people. Moving toward that kind of access is important, but it comes at a cost. Glittering with reflected sunlight, these first orbiters, sent up in the past year, are brighter than 99 percent of the 5,000 or so other satellites now circling Earth, and obviously there are going to be a lot more. This sudden increase is bad for astronomy: the probability of a Star-link satellite crossing a telescope’s field of view and ruining an observation will be quite high near sunset. For that reason, my fellow astronomers have signed a petition (请愿书) calling for governments to protect the night sky from this invasion.

In response to protests, SpaceX has promised to address the visibility problem by, for example, applying experimental coatings — essentially painting the satellites black — but the company’s aggressive launch schedule remains unchanged. And the satellites’ illuminated (被照亮) surfaces are mostly their solar panels — exactly the part that cannot be painted over.

Unfortunately, at present no regulations govern how bright a single satellite can be, let alone thousands of them together. Even if there were such regulations, one nation’s laws can not hinder (阻碍) another country’s launches. Space literally has no borders, and the sky will need to be protected at an international level. As a consequence, we hope that the United Nations will find a way to think outside of the box to save the sky for everyone.

When I was growing up in Montana, it was a game to be the first to find a moving satellite among the host of stars in the night sky. Soon it could be a game to recognize the constellations (星座) behind a swarm of moving points of light.

1. What is the writer’s attitude toward Space X’s launching plans?

A．Indifferent.

B．Doubtful.

C．Optimistic.

D．Disapproving.

2. Why have my fellow astronomers signed the petition?

A．SpaceX plans to send too many Star-line satellites into space.

B．The Star-line satellites will possibly ruin an observation near sunset.

C．The first orbiters are brighter than most of other satellites circling Earth.

D．Space X fails to provide high-speed Internet to people around the world.

3. According to the author, who should shoulder the responsibility to save the sky?

A．The United States.	B．The United Nations.
C．The company SpaceX.	D．Just one nation.

4. What can be a suitable title for the text?

A．Preserve the Night Sky	B．Ban Star-line Satellites
C．Observe the Stars Attentively	D．Protest against Space X

5 . Not too big, not too small. Not too hot, not too cold. A newly discovered planet looks just right for life as we know it, according to an international group of astronomers.

Orbiting a star about 500 light years away, the planet called Kepler-186f is about the same size as Earth. As this astronomer’s explanation shows, it orbits its star at the right distance for liquid water on the surface. That is an essential condition for life as we know it.

But it is not exactly like Earth, NASA planetary scientist (行星科学家) Elisa Quintana said via Skype. “It’s more of an Earth’s cousin. It’s not an Earth’s twin. It shares the same characteristics as Earth, but their parent stars are very different.” said Quintana.

Kepler-186f orbits a star that is smaller and cooler than our sun. But, writing in the journal Science, the astronomers say the planet appears to be a closer relative than most of the hundreds of others discovered so far. Some are large gas-covered giants with thick atmospheres. Others orbit too closely to their stars and are too hot for life.

Two planets discovered last year are in the right orbit and might be good candidates (候选人) for life Quintana says, but they are a bit bigger than Earth.

“For the first time, we can actually say we now have a planet that is both Earth-sized and orbits in its star’s habitable (适合居住的) zone,” she said.

“It may be the first time, but it probably is not the last,” says Massachusetts Institute of Technology astrophysicist Sara Seager. She spoke to VOA via Skype.

1. What’s the best title of the passage?

A．New Earth-size planet found	B．Kepler-186f’s orbit
C．A NASA planetary scientist	D．Planets

2. Which phrase can replace the underlined phrase “an essential” in Paragraph 2?

A．An unimportant.	B．A dangerous.
C．A difficult.	D．A necessary.

3. According to the passage, which statement is NOT true?

A．Kepler-186f is at the right distance for liquid water on the surface.

B．Kepler-186f is exactly as big as Earth.

C．Kepler-186fs and the Earth’s parent stars are very different.

D．The star that Kepler-186f orbits is smaller and cooler than our sun.

6 . Junk can be an annoying thing. But dealing with the junk in your room is quite easy — just remove it. How about the junk in space? NASA is considering using lasers(激光) to move space junk around the Earth.

Scientists suggest that the energy contained in the laser could change the junk’s course by 650 feet (about 198m) a day. While that won’t be enough to knock it out of orbit, it could avoid a collision with a space station or satellite. Where does space junk come from and why should scientists want to move it?

There two main sources of space junk. One is exploded rockets. The largest amount of junk was caused by a rocket sent up into space in 1994. Its explosion in 1996 created a cloud of some 300,000 fragments(碎片), each at least 4 mm in size. Another source is astronaut error. Suppose an astronaut is doing a repair in space, he or she drops the wrench(扳手) and it’s gone forever. It spins into orbit, probably at a speed of around 6 miles(1.6km) a second.

Space junk is a huge threat to the lives of astronauts in space shuttles and on the International Space Station. A tiny speck(微粒) of paint from a satellite once dug a hole in a space shuttle window nearly half a centimeter wide.

Scientists are fully aware of this problem. They monitor the paths of space fragments and immediately report any threat of an orbital impact. Some 20,000 pieces of rubbish are currently being monitored in low-Earth orbit.

So far no effective ways have been found to avoid space junk.

Is there any danger of us on Earth getting hit by space junk? Probably not. Scientists say most space objects that re-enter the Earth’s atmosphere burn up or re-enter over water. So relax! The chance of getting hit by a falling astronaut’s glove is small.

1. According to the passage, which of the following probably is the greatest source of space junk?

A．Space shuttles.	B．Rocket fragments.
C．Used satellites.	D．Astronauts’ tools

2. To deal with space junk around the Earth, NASA will use lasers to ________.

A．knock space junk out of orbit	B．destroy the space junk directly
C．move the space junk off course	D．prevent the space junk from spinning

3. What can we learn from the passage?

A．Scientists don’t think the space junk problem is serious.

B．There are currently 20,000 pieces of rubbish around the Earth.

C．Scientists have been following the paths of space junk closely.

D．Several ways have been worked out for astronauts to avoid space junk.

7 . Jupiter, the largest planet in our solar system, is one of the most interesting. It was named after Jupiter, the most important Roman god. Nicknamed “King of Planets”, it is the fifth planet from the Sun and the fourth brightest object in the sky. Before the invention of the telescope, Jupiter was thought to be a bright star.

In 1610, the famous astronomer Galileo realized that Jupiter was a planet and revolved around (围绕……转动) the Sun. He also noticed that it had four large moons. These are known as the Galileo moons. The biggest is Ganymede, and it’s larger than the planet Mercury. Next in size is Calisto, which is the farthest away from Jupiter. Io is the closest to the planet and has many active volcanoes. Europa, the smallest of the Galileo moons, is covered with ice, and scientists believe there may be an ocean underneath.

Galileo said that Jupiter wasn’t a star but a planet. Before his time, people believed that the Sun, stars and other planets all revolved around the Earth. However, Galileo proved that the Sun was at the center of the solar system!

Jupiter is farther out in the solar system than the Earth, so it takes longer to revolve around the Sun. This means that one year on Jupiter as long as 11.6 Earth years. However, a day on Jupiter is much shorter, only 9.8 Earth hours. This is because it spins a lot faster than the Earth does. Another of Jupiter’s interesting features is its “Great Red Spot”. This large red spot on the surface of the planet is a huge storm, like a hurricane but bigger. It covers an area twice as big the Earth and has been going on for at least 400 years!

1. Which of the following is TRUE about Jupiter?

A．It’s the fourth planet from the Sun.

B．It’s the brightest object in the sky.

C．Either the Earth or Mercury is bigger than it.

D．One of its moons might have an ocean underneath.

2. Which of the Galileo moons is the farthest away from Jupiter?

A．Io	B．Europa
C．Calisto	D．Ganymede

3. Why is Galileo’s discovery important?

A．Because Jupiter was thought to be smaller than the Earth.

B．Because it proved that the Earth isn’t the center of the solar system.

C．Because Jupiter was found to be the only planet in the solar system.

D．Because it proved that the Earth goes around the Sun.

4. What’s the passage mainly about?

A．The features of the planet Jupiter.

B．How Jupiter moves in the solar system.

C．Galileo’s greatest contribution in astronomy.

D．Differences between Jupiter and other planets.

8 . In the first days of space exploration, one concern was the possibility that astronauts or spacecraft might be hit by meteoroids. Scientists calculated that this possibility was extremely small because meteoroids are rare. Astronauts and spacecraft, on the other hand, would almost certainly encounter space debris, which poses a greater threat.

However, in the 60 years since the beginning of space exploration, large quantities of human-made orbital debris have accumulated. Much of the debris consists of satellites that have stopped functioning or rocket booster sections that separated from the main spacecraft. Some of the debris consists of items lost by astronauts. Still more of the debris is the result of collisions. such as when one satellite collides with another or with a large piece of debris.

NASA estimates there are millions of debris particles that are too small to be tracked. These circle Earth at a speed of up to 17, 500 miles per hour, making even the smallest particles dangerous. One scientist calculated that a chip of paint hitting the window of a spacecraft at orbital speeds will hit with the same amount of force as a bowling ball traveling at 60 mph. Such an impact occurred on the space shuttle Challenger's second flight.

Larger objects are even more dangerous, but they can be monitored and avoided. Many satellites have the ability to adjust their course slightly and can be remotely directed to avoid collisions with larger objects that would damage or destroy the satellites. NASA and the European Space Agency (ESA) have departments dedicated to cataloging, modeling, and predicting the movements of space debris.

To avoid adding to the amount of debris, obsolete satellites may need to be able to take themselves out of orbit as their usefulness comes to an end. Until a way to remove these remains is implemented. however. those 500, 000 pieces of large fragments, along with the millions of smaller pieces, will continue to orbit Earth.

1. According to the text, which of the following statements is TRUE?

A．Up to now, there is still no efficient way to clean the space debris.

B．Satellites should be monitored more to avoid being hit by space debris.

C．Most of the space debris consists of satellites that have stopped functioning.

D．To decrease space debris, the number of the satellites sent to space should be controlled.

2. What’s mainly discussed in Paragraph 2?

A．Problems caused by old satellites and equipment.

B．Better tracking of the space debris that is orbiting Earth.

C．The types of space debris that is causing problems.

D．Why space exploration was carried out in the beginning.

3. What does the underlined word "obsolete" in the last paragraph probably mean?

A．private.	B．artificial
C．useful	D．outdated.