IELTS Academic Reading Practice Test 82

A kite is, at its simplest, a heavier-than-air object tethered to a line and kept aloft by the wind. Although to many people it is little more than a child's toy, the kite is among the oldest flying machines ever built, and its influence extends far beyond recreation. Over more than two millennia, kites have carried scientific instruments into the atmosphere, helped inventors understand the principles of flight, served armies as signalling devices and, most recently, begun to attract serious interest as tools for generating renewable energy.

The earliest written evidence indicates that kites originated in China, where they were being flown by the fifth century BC. According to tradition, Chinese military engineers used kites to estimate the distance to enemy fortifications by flying them on a fixed length of line, and also to send simple signals between units. From China, the technology spread along trade routes to Korea, Japan and other parts of Asia, and eventually to India and the Middle East. By the time European travellers described them in the sixteenth and seventeenth centuries, kites had assumed a wide variety of forms. In some regions, kites also became associated with ceremonies.

In Europe the kite became a scientific instrument during the eighteenth century. In 1749 the Scottish astronomer Alexander Wilson used a train of kites to lift thermometers to a considerable height, an early attempt to study the temperature of the upper air. Three years later Benjamin Franklin, in a famous though dangerous experiment, flew a kite in a thunderstorm in order to show that lightning is an electrical discharge. Franklin's experiment is often described as proof of the electrical nature of lightning, although the exact details remain uncertain.

In the nineteenth century, kites played a central role in the emerging discipline of aeronautics. Sir George Cayley, the English engineer who first identified the forces of lift, weight, thrust and drag, built large gliders and also experimented with kites to test his ideas. In the 1890s, the Australian inventor Lawrence Hargrave developed the box kite, whose construction made stable flight possible and which became the basis for many early aircraft. The Wright brothers, before their first powered flight in 1903, built large kites to test their method of controlling a wing by twisting it, now known as wing warping. Alexander Graham Bell also designed enormous tetrahedral kites in the hope of producing a powered flying machine.

Despite their long association with leisure, kites continued to serve military purposes well into the twentieth century. During the Second World War, the United States Navy used specially designed target kites for gunnery practice, and kites were also employed to lift radio antennas from life rafts and remote positions. Even earlier, during the Boer War and the First World War, man-lifting kites developed by the British army were occasionally used to raise observers above the battlefield, although they were soon supplanted by tethered balloons and aircraft.

The materials from which kites are made have changed almost beyond recognition. Early Chinese kites were constructed from bamboo frames covered with paper or silk, and even fine split bamboo was used so that the structure would flex rather than break in strong wind. Today, most kites are made from synthetic fabrics such as ripstop nylon, supported by lightweight carbon fibre or fibreglass rods. The development of strong, low-stretch lines has allowed the emergence of high-performance power kites, which are used in sports such as kitesurfing and kite buggying. In these activities, the kite functions not as a toy but as a sail, pulling the user across water or land. The popularity of these sports has grown rapidly, and kiteboarding made its Olympic debut in 2024.

The flight of a kite is often misunderstood. A kite does not float on the wind; rather, it is held at an angle to the airflow so that the wind passing over it generates lift, just as it does over an aircraft wing. The bridle, the arrangement of lines attached to the kite, determines the angle at which the kite meets the wind, while the tether line provides tension that prevents the kite from simply blowing away. If the wind is too weak, no amount of running can produce sustained flight for most designs; if it is too strong, the kite may become unstable unless its shape can change or the flyer adjusts the angle.

In many parts of the world, kite flying remains a social event rather than a solitary pastime. The Indian festival of Makar Sankranti is accompanied by mass kite flying from rooftops. In Japan, kites are flown at New Year and during seasonal festivals. The city of Weifang in China hosts a major international kite festival, attracting teams from many countries. Kite fighting, in which flyers attempt to cut one another's lines using abrasive coated line, is a popular competitive tradition in Afghanistan, Pakistan and parts of South America.

More recently, engineers have explored the kite's potential as a source of electricity. Airborne wind energy systems use large kites that fly in loops at high altitude, pulling a tether connected to a ground-based generator. Because winds are stronger at altitude, such systems could generate electricity more cheaply than conventional wind turbines, though the technology remains at an early stage. Proponents argue that the method uses less material than a conventional wind turbine.

The exploration of Mars has long relied on stationary landers, but the planet's surface is too varied for one spot to reveal the history of an entire world. Wheeled rovers solve this problem by moving across the landscape, examining rocks and soil at many different locations. Because radio signals take many minutes to reach Mars, direct human control is impossible, so each rover carries software that allows it to drive itself over short distances. In effect, a Mars rover is a mobile robot that must act as a geologist while also protecting itself from one of the most hostile environments ever faced by a machine. Rovers must also choose their own targets, deciding where to aim cameras and which rocks to examine, so that scientists on Earth receive only the most valuable data.

The first successful rover was Sojourner, which reached Mars in 1997 as part of NASA's Pathfinder mission. It was a small vehicle, only about ten kilograms, and could travel at a maximum speed of less than one centimetre per second. Although its range was limited to a few metres around the lander, Sojourner demonstrated that a mobile robot could operate reliably on the Martian surface. The mission also tested a new entry and landing system using airbags, which later became standard for NASA's next generation of rovers. Pathfinder landed in a flood channel named Ares Vallis, a site chosen because it might contain rocks washed down by ancient floods.

NASA's Mars Exploration Rovers, Spirit and Opportunity, arrived in January 2004. Each was designed to operate for just 90 days, but both far outlived expectations. Their primary objective was to search for evidence that liquid water once existed on the surface. Opportunity discovered small spherical deposits of the mineral hematite, nicknamed 'blueberries', which on Earth form in water, and also examined layered rock formations that pointed to a wet ancient environment. Spirit, on the other side of the planet, found silica-rich soil. Spirit became stuck in soft ground in 2009 and lost contact in 2010, while Opportunity continued to travel more than 45 kilometres before a severe dust storm in 2018 ended its mission.

The next rover, Curiosity, landed in Gale Crater in 2012 and represented a major step in capability. About the size of a small car and powered by a nuclear generator, Curiosity was designed to study Mars's climate and geology and to assess whether the planet could once have supported microbial life. Early in its mission it found rounded pebbles in an ancient streambed, direct evidence that water had flowed on the surface. It later detected organic molecules in drilled rock samples and observed seasonal variations in atmospheric methane, a gas that on Earth is often produced by living organisms. Gale Crater was selected because it contains a central mountain, Mount Sharp, whose layers preserve a record of changing conditions over hundreds of millions of years.

Perseverance, which landed in Jezero Crater in February 2021, is the most sophisticated rover yet sent to Mars. Its main goal is to seek signs of ancient microbial life, particularly in an area that was once a river delta. Perseverance has been collecting and sealing rock samples that a future mission may bring back to Earth. It also carried a small helicopter called Ingenuity, which in April 2021 performed the first powered flight on another planet. Ingenuity's success suggests that aerial vehicles could explore Mars far faster than any wheeled rover. Jezero was chosen because the delta there may have trapped organic matter.

The United States is not alone in driving on Mars. In May 2021 China's Zhurong rover landed in Utopia Planitia, making China the second country to operate a rover on the Martian surface. Zhurong carried a ground-penetrating radar and spent several months studying the local geology. Its data contributed to evidence for possible buried water ice in the region, and its mission demonstrated China's growing capacity for planetary science. The rover was designed to operate for around 90 days but remained active for over 300 days before entering hibernation. Its work showed that a relatively modest rover could conduct serious geological fieldwork.

Operating a rover on Mars presents enormous technical challenges. Dust storms can block sunlight and reduce the power available to solar panels, while extremely low temperatures threaten delicate components. Wheels have evolved to cope with sharp rocks and soft sand, and engineers now use flexible designs that can shed damage. Because of the communication delay, rovers must be able to assess hazards and decide their own paths, a capability known as autonomous navigation. The choice between solar and nuclear power depends on the mission's location, season and expected lifetime. Engineers also monitor the rover's temperature and use heaters to keep its electronics within safe limits.

The ultimate aim of many rover missions is to prepare the way for human exploration. Samples collected by Perseverance are intended to be returned to Earth in a future international campaign, and data about Martian dust, radiation and resources will help engineers plan crewed bases. Rovers have already mapped places where water ice may be accessible, and their findings have helped shift the question from whether Mars was ever habitable to where and when life might have arisen. In this sense, the wheels that crawl slowly across the red planet are also the first advance scouts of a longer human journey. Smaller scout rovers may one day accompany human crews, exploring sites before astronauts arrive.

Few features of the modern office are as widely disliked as the open plan. Employers introduced it to cut costs and encourage collaboration, but a growing body of research suggests that it does so at a price. The most serious problem is not the lack of privacy or the visual distractions; it is noise. For a surprising number of workers, the noise of an open plan is not a minor irritation but a constant drain on the mental resources needed to think clearly. The belief that noise simply becomes part of the background is widespread, but it is not supported by the evidence.

Cognitive psychologists have long known that the human brain has a limited capacity for attention. Even tasks that seem automatic, such as remembering a short list of numbers while reading a note, can be disrupted by sounds that are irrelevant to the task. Laboratory studies consistently demonstrate the 'irrelevant sound effect', in which background speech interferes with memory for ordered information. The effect occurs even when the speech is quiet and the listener is trying hard to ignore it, because the brain automatically processes the sound of other people's voices. This is not simply a matter of annoyance; measurable errors increase when speech is played in the background.

Not all noise is equally harmful. Continuous, predictable sounds such as the steady hum of an air-conditioning system tend to be easier to tune out. The most damaging kind of noise appears to be speech that is intermittent and unpredictable, particularly when it is just intelligible enough for the listener to follow. A telephone conversation in which only one side is audible can be especially distracting, because the brain keeps trying to fill in the missing parts. Music with lyrics can have a similar effect, although the evidence is mixed.

Some managers argue that employees become used to office noise over time. The truth is more complicated. Habituation reduces the annoyance people report, so after a few weeks they may say that the noise no longer bothers them. However, this does not mean that the interference has disappeared. Several studies have found that the effect of irrelevant speech on memory remains strong even after long periods of exposure. In other words, workers may simply stop noticing how much the noise is costing them. The brain's auditory system does not have an off switch, so the processing of sound continues whether or not the person pays attention.

Part of the problem lies in the way productivity is measured. In many workplaces, productivity is judged by the speed at which routine tasks are completed, such as answering emails or processing orders. Noise has relatively little effect on these simple, well-learned activities. But the knowledge economy depends increasingly on work that requires sustained attention: reading complex documents, analysing data, writing reports and solving unfamiliar problems. It is precisely this kind of deep work that suffers most when speech intrudes. A task that can be done on automatic pilot may be unaffected, but a task that requires holding several ideas in mind at once is easily derailed.

The search for solutions has produced a range of partial answers. Quiet rooms and telephone booths allow workers to escape the general hubbub for concentrated tasks, but they are often too few and too far away. Sound masking systems, which introduce a soft background noise, can reduce the intelligibility of distant speech, yet they do not eliminate the problem. The widespread use of headphones is a sign of failure rather than success: employees are forced to create their own isolation because the office does not provide it.

A deeper issue is cultural. Open plans are often promoted as flexible spaces where people can interact spontaneously and share ideas. This is a real benefit, and some tasks genuinely require rapid exchange. But the same openness that supports collaboration can undermine the individual thought on which much collaboration depends. A workplace that treats all hours as meeting hours, and all space as social space, cannot also give its employees the quiet they need to think. Collaboration and concentration are often presented as opposites, but in successful teams they are complementary rather than competing.

There is no perfect office layout, and the answer is not to return to rows of closed offices, which have their own disadvantages. The most sensible approach, in my view, is to design for variety. A well-planned office should include quiet zones where conversation is not permitted, enclosed rooms for private work, and open areas for discussion.

Clear norms matter as much as walls: employees need to know that concentrating is valued, and that a closed door or a 'do not disturb' signal will be respected. Such choices must reflect the fact that different employees have different sensitivities to sound; some can work through almost anything, while others need almost total silence.

Noise, in short, is a form of environmental pollution in the office, and it should be managed as carefully as lighting or temperature. Employers who ignore it are not only harming their staff's wellbeing; they are also giving up productivity that they never measure. The knowledge worker's most important tool is a train of thought, and every unnecessary interruption is a tax on that tool. In a competitive economy, the ability to protect deep attention may prove to be a greater advantage than the latest collaboration software. Until that lesson is learned, the open plan will continue to be a well-intentioned experiment with unmeasured costs.