IELTS Reading Practice Test 7: Free, with Answers

AWhen the Soviet Union launched Sputnik 1 in 1957, it was the only artificial object orbiting the Earth. Today, according to the European Space Agency, space surveillance networks are tracking around 40,000 objects, of which only about 11,000 are working satellites. The rest are pieces of junk: old satellites that no longer work, the upper stages of rockets, and fragments produced by explosions and collisions. Every launch adds to the problem, because rockets often leave their spent upper stages in orbit, and few satellites have been designed to be removed at the end of their working lives. And these are only the objects large enough to be tracked. Scientists estimate that there are more than a million pieces larger than one centimetre, and countless smaller ones, too small to be seen from the ground.

BSize can be misleading, because in orbit even tiny objects are extremely dangerous. In low orbits, satellites and debris travel at around 28,000 kilometres an hour, roughly ten times the speed of a rifle bullet. At such speeds, a fragment just one centimetre across can put a satellite out of action, and one of ten centimetres can destroy it completely. The International Space Station, which carries people, is protected by special shielding against the smallest particles, and engineers designing new satellites must decide how much protection to add, knowing that every extra kilogram makes a launch more expensive, but it has had to change its orbit around forty times since 1999 to avoid larger pieces of debris.

CThe possibility that debris might become a serious threat was first explained in 1978 by two NASA scientists, Donald Kessler and Burton Cour-Palais. They pointed out that every collision between objects in orbit produces fragments, each of which can cause further collisions, producing yet more fragments. Once the number of objects in a particular orbit passed a certain point, they argued, collisions would continue even if no more satellites were ever launched. This chain reaction, now known as the Kessler syndrome, could eventually make some orbits too dangerous to use. At the time, their paper attracted relatively little attention outside the specialist community, because the number of satellites was still small.

DTwo events in the early twenty-first century brought this warning closer to reality. In 2007, China tested an anti-satellite weapon by destroying one of its own old weather satellites, creating more than three thousand pieces of trackable debris, many of which are still in orbit. Two years later, an inactive Russian military satellite crashed into a working American communications satellite above Siberia. It was the first accidental collision between two complete satellites, and it produced more than two thousand trackable fragments. Together, the two events showed how a single incident can add thousands of new objects to the catalogue within seconds, and how long the consequences can last.

EHow long debris remains in orbit depends largely on its height. Objects in the lowest orbits are gradually slowed down by the thin upper atmosphere, and eventually fall towards the Earth and burn up, usually within a few years. Higher up, however, where the atmosphere is almost non-existent, debris can remain for centuries. Because the upper atmosphere expands when the Sun is especially active, periods of high solar activity actually help to clear the lowest orbits more quickly. For this reason, international guidelines have long recommended that satellites in low orbit should be brought down within twenty-five years of the end of their missions. In 2022, the United States went further, requiring American-licensed satellites to be removed within five years.

FPreventing new debris is not enough; some of the existing junk may have to be removed. In 2018, a small British-led mission called RemoveDEBRIS, launched from the International Space Station, successfully caught a target in orbit with a net, and the following year it fired a harpoon into a target attached to the spacecraft. Other missions now in development plan to grab old satellites with robotic arms and pull them down into the atmosphere, while some engineers have proposed using powerful lasers on the ground to nudge small fragments into lower orbits, an idea that remains controversial. The obstacles are considerable, however. Such missions are expensive, and international law means that one country cannot remove another country's debris without permission, even when that debris threatens its own satellites.

GMeanwhile, the number of satellites is rising faster than ever, because several companies are launching networks of thousands of small satellites to provide internet access around the world. Supporters argue that these satellites operate in low orbits, where any failed ones will soon fall back to Earth. Critics are less confident. Astronomers complain that the satellites leave bright streaks across images of the night sky, and safety experts warn that, with so many objects in similar orbits, the risk of collisions is bound to increase unless space traffic is managed far more carefully than it is today.

In the 2010 football World Cup, England's Frank Lampard struck a shot that hit the crossbar, bounced well over the German goal line and spun back out. The referee, who had not seen it clearly, waved play on, and the goal was never given. Television viewers around the world, watching the replay within seconds, could see what the officials could not. The incident did more than years of argument to change the minds of football's governing bodies, which had long resisted technology, and four years later, at the 2014 World Cup in Brazil, goal-line technology was used for the first time. Similar systems had already been adopted elsewhere: tennis players have been able to challenge line calls using the Hawk-Eye camera system since 2006, and cricket introduced its Decision Review System in international matches two years later. In each case, the change followed a period of intense public criticism of officials whose errors had been exposed by television.

The most ambitious step came in 2018, when video assistant referees, or VAR, were used at a World Cup for the first time. A team of officials watching replays away from the pitch could now advise the referee on goals, penalties, red cards and cases of mistaken identity. According to FIFA, the proportion of correct decisions on such incidents rose from around 95 per cent to over 99 per cent. Supporters of the system point out that, before its introduction, a single wrong decision could determine the outcome of a tournament for which players had spent four years preparing. By that measure, at least, the case for technology seems overwhelming.

Yet accuracy is not the only thing that makes a decision fair, and the experience of different sports suggests that technology works far better in some than in others. In tennis, the questions it answers are purely factual: the ball was either in or out, and a camera can determine that more reliably than any human eye. Play also stops naturally after every point, so a review costs only a few seconds. Football is very different. Many of its most important decisions, such as whether a defender's arm was in an unnatural position or whether a challenge was reckless, depend on the referee's judgement, and no number of replays can turn a matter of opinion into a matter of fact. Different officials watching the same images frequently reach different conclusions. This is not a failing of the technology but a consequence of the rules themselves, many of which require officials to assess intention, recklessness or the degree of force used.

Technology also imposes costs that are considerably less obvious than its benefits. Reviews can take several minutes, interrupting the flow of a game that was designed to be continuous, and supporters in the stadium, who usually cannot see the replays, are often left with no idea what is being examined. The celebration of a goal, once the most spontaneous moment in sport, has become provisional: players and fans now glance anxiously towards the referee before they dare to rejoice. The constant possibility of a review has also altered the psychology of the game, encouraging appeals and protests rather than acceptance of the referee's authority. Offside decisions illustrate the problem particularly clearly. Since the 2022 World Cup in Qatar, a semi-automated system using cameras under the stadium roof, which track up to 29 points on each player's body many times a second, has been able to detect offside positions measured in centimetres. Offside is a factual question, and I see no reason to stop using technology to settle it; but a goal disallowed because a player's shoulder was a few centimetres beyond a defender is correct only in the narrowest sense.

None of this implies that football should abandon technology altogether. Goal-line systems, which give an instant and indisputable answer, have been an unqualified success, and VAR has prevented a number of serious injustices. What is needed, rather, is a clearer understanding of the purposes that technology is intended to serve. In my view, it should be used to correct obvious factual errors, not to re-referee every incident in slow motion. Reviews should be subject to a strict time limit; if an error is not clear after a minute or so, the referee's original decision should stand. Offside could allow a small margin of tolerance, so that only clear advantages are penalised. Such principles would require football's lawmakers to accept that some errors will remain, but that is surely preferable to a system that promises perfection and delivers frustration.

Above all, the people watching deserve to understand what is happening. At the 2023 Women's World Cup, referees explained their decisions after video reviews over the stadium loudspeakers, as rugby referees have long done, and the reaction from spectators was largely positive. Cricket offers a further lesson: by limiting the number of reviews each team may request, it ensures that the system is used for genuine doubts rather than as a tactical delay. Such openness costs nothing and makes even an unpopular decision easier to accept. Fairness in sport depends not only on getting decisions right but on decisions being seen to be made in a way that everyone can follow. Technology can serve that goal, but only if it is designed around the game, rather than the game being reshaped around the technology.