IELTS CAM Inspired 18 - Reading Test 1 with Practice Test, Answers And Explanation
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IELTS CAM Inspired 18 - Reading Test 1 With Practice Test, Answers And Explanation
Passage
❓ Câu hỏi passage 1
Question 1 - 3
Complete the sentences below.
Choose NO MORE THAN TWO WORDS AND/OR A NUMBER from the passage for each answer.
1
The upright growing columns are planted with raspberries, herbs and
.
2
Once fully operational, the site will yield up to
of produce each day.
3
In time the farm could account for as much as a tenth of the city's overall
.
Question 4 - 7
Complete the table below. Choose ONE WORD ONLY from the passage for each answer.
Growth
Selection
Sale
Intensive farming
many kinds of
4
applied;
methods harm air quality
poor quality;
types picked for their ability to endure lengthy
5
only a small share of the total income reaches the
6
Aeroponic urban farming
no soil used;
nutrients mixed into
water, which is reused
crops chosen for their
7
Question 8 - 13
Do the following statements agree with the information given in the Reading Passage?
TRUE if the statement agrees with the information
FALSE if the statement contradicts the information
NOT GIVEN if there is no information on this
8
Merckx expects the farm will eventually supply the greater part of the city's food.
9
Verdantis has received interest from clients in many parts of the world.
10
The nutrients that enrich the water are made by Verdantis itself.
11
The aeroponic method uses more water than a traditional farm growing the same quantity of food.
12
The cost of the aeroponic equipment has fallen in recent years.
13
There are certain crops, such as potatoes, that cannot yet be grown using this method.
Passage
❓ Câu hỏi passage 2
Question 14 - 18
Reading Passage 2 has 7 paragraphs, A-G.
Which paragraph contains the following information?
Write the correct letter, A-G.
14
harmful effects on a wood that arise when owners judge it purely by profit
15
a list of the features that together determine how valuable a tree is
16
the possibility of using wood to power road vehicles
17
the naming of several insects that damage trees
18
an informal label for trees of little commercial use
Question 19 - 21
Match each statement with the correct timber cut, A, B or C.
List of Findings
A
a Shelterwood Cut
B
a TSI Cut
C
a Salvage Cut
19
to clear away trees that have become diseased
20
to spread the earnings from a wood over a number of years
21
to create a wood whose trees are all roughly the same age
Question 22 - 26
Complete the sentences below.
Choose ONE WORD ONLY from the passage for each answer.
22
Clearing away lifeless timber lowers the
that a fire would otherwise consume.
23
The uppermost part of a felled tree is left in place so that the
it holds are returned to the earth.
24
Trees whose trunks are full of
should be kept, because they house creatures that feed on insects.
25
Certain small trees — the
is one example — give birds and wildlife something to eat.
26
A species that is
in a particular wood should be spared, since it broadens the mix of trees growing there.
Passage
❓ Câu hỏi passage 3
Question 27 - 31
Reading Passage 3 has 6 sections, A-F.
Which section contains the following information?
Write the correct letter, A-F.
27
figures comparing the current rate of satellite launches with that of earlier years
28
an attempt to sort debris according to physical features such as size
29
the observation that, in principle, space is roomy enough for craft to keep well clear of one another
30
the way different parties have begun working together against a common danger
31
an analogy that likens managing orbital traffic to the running of a busy transport hub
Question 32 - 35
Complete the summary below.
Choose ONE WORD ONLY from the passage for each answer.
The Joint Orbital Debris Advisory Council
The council offers guidance on ways of safeguarding the enduring of orbital space. It recommends that, once a satellite stops working, any surplus or compressed gas that might set off a ought to be released. Although those who run large satellite fleets acknowledge their duties as caretakers of space, Tomasz Reinholt points out that operators who become are not likely to make removing their satellites a priority.
Question 36 - 40
Match each statement with the correct person, A, B, C or D.
List of Findings
A
Priya Anand
B
Ingrid Halvorsen
C
Diego Marchetti
D
Tomasz Reinholt
36
There may come a stage at which the harm done in orbit can no longer be undone.
37
Working out the precise whereabouts of all debris would remove almost every risk of collision.
38
Orbital space should stay open to everyone and be preserved for those who follow.
39
The recorded positions of certain objects do not match one another.
40
A guideline concerning end-of-life satellites is ignored by many operators.
DOL IELTS Đình Lực
21/10/2026
📖 Bài đọc passage 1
Urban farming
In Rotterdam, urban growers are testing a soil-free way of farming that needs less room and fewer resources. Might it help cities cope with the risks hanging over our food supplies?
High above a recently opened concert hall in the west of Rotterdam, what is said to be the world's largest rooftop farm has begun to yield its first crops. From tall plastic tubes tumble raspberries — small, deep red and remarkably full of flavour — their roots left dangling inside the hollow columns, dozens to a tube. Nearby, a second set of identical tubes sends out rows of spinach, and beside them sit fragrant herbs: basil, thyme and mint. Across the way, shallow trays filled not with earth but with coconut fibre hold cherry tomatoes, glossy peppers and deep-green kale.
It was on the roof of his own Rotterdam apartment block, a little over six years ago, that Joost Merckx — an engineer who also advises on sustainability — first began tinkering with vertical farming and the soil-free growing towers, known as aeroponic systems, that these plastic tubes form. The plot above the concert hall is far larger, covering some 12,000 square metres, about the size of a large city block. In a single day, the young farmers who look after it have already gathered 2,600 heads of spinach and 130 crates of raspberries. Once the other two-thirds of the space is planted, a staff of 25 will bring in as much as 800 kg of around 40 kinds of fruit and vegetables daily. 'Feeding an entire city this way is never going to happen, of course,' Merckx warns. 'The city puts real limits on what you can grow, and where. Still, if enough wasted space were converted like this, meeting five to ten per cent of the city's demand is not out of the question.'
What matters most, perhaps, is that all this serves as a working advertisement for Verdantis, Merckx's thriving urban-farming consultancy, which these days receives enquiries from every corner of the globe wanting help to design and build a new kind of soil-free city farm. He lists the benefits readily. 'It bothers me that the fruit and vegetables on our plates have usually been treated with as many as twenty different chemicals, and that the intensive methods behind them pour out greenhouse gases. It bothers me, too, that the average item has been trucked some 1,800 chilled kilometres before I eat it, that it tastes of little because the varieties were bred to survive long trips rather than to taste good, and that of every euro I hand over, roughly 80 per cent goes to distributors and haulage firms rather than the farmers.'
The soil-free approach, by contrast, needs nothing more than a modest flow of water, laced with organic nutrients and pushed endlessly around a sealed loop of pipes, towers and trays. 'The food is grown right here and sold just below us, so it hardly moves at all,' says Merckx. 'You can pick your varieties for their taste instead of their ability to survive weeks in transit, and you harvest them at their peak rather than ahead of it.' Because the roots are misted every ten minutes with water that is then captured and reused, no soil is worn out and the system gets by on 90 per cent less water than an ordinary intensive farm producing the same amount.
None of this makes urban farming itself a novelty. City agriculture is thriving everywhere from Singapore to Chicago and Seoul to Bangkok, with herbs raised in abandoned shipping containers and mushrooms in disused metro tunnels. The gear, Merckx notes approvingly, is light enough to sit on almost any level roof and costs little — somewhere between €90 and €140 for each square metre. Running it is cheap as well, since it draws only a small fraction of the power that some other methods demand.
Food produced in this way usually costs more than that from conventional intensive farms, though less than what soil-based organic growers charge. Naturally the technique has its boundaries, and a good deal of what it produces belongs to the warmer months. 'Root crops are still beyond us,' Merckx admits. 'Radishes are fine, but the long roots of carrots or potatoes rule them out, fruit trees are simply impossible, and beans swallow up space while giving back very little.' Even so, the sort of urban farming now under way in Rotterdam forms one piece of a larger, rapidly shifting picture, one that is drawing the growing of food ever closer to where we live.
How making use of low-grade timber — sometimes called low-use wood — for energy can support the sustainable management of forests
A
A. For a long time, woodland owners in Pennsylvania prized their trees for one thing only: high-grade sawtimber. When a stand was cut, the finest, straightest stems were taken out and the misshapen trees — those least suited to the ground they stood on — were left behind. This habit, called 'high-grading', has handed today's forests a legacy of 'low-use wood'. Foresters sometimes dismiss such trees as 'weed trees', and across the country they are far from scarce. They fetch little in conventional timber markets, crowd better stems as they compete for room, shade out the seedlings meant to replace them and sap a stand's overall vigour, leaving the forest more exposed to storms and disease. Cutting aimed squarely at this low-use wood helps owners tackle these problems, and markets for wood energy give them a reason to do so.
B
Those markets are useful because they will take timber of a lower grade, and price, than any sawmill would consider. In Pennsylvania most wood burned for energy is turned into heat or electricity by combustion: many schools and hospitals run their heating on wood-chip boilers, countless homes rely on wood for warmth, and several power stations blend wood into the peat they burn for electricity. Wood can also be turned into gas for power, or processed into liquid fuels such as ethanol and petrol — the very fuels that drive lorries and cars. Every one of these products draws chiefly on low-use wood, and several cutting methods, each able to improve a forest's long-term quality, are built around supplying it.
C
Just how much any tree is 'worth', though, is far from fixed. It turns on a range of things — species, size, shape, condition, quality, the part it plays in the wood and how easily it can be reached — and on what the owner wants from the forest. The same tree may strike two people quite differently. To a timber merchant, a tall oak with a clean, straight trunk is a valuable saw-log or future furniture; to an owner who cares about wildlife, that trunk's worth lies in the food and shelter it gives animals. Likewise, once fungal decay — a defect foresters call heart-rot — has crept into a stem, its timber value drops sharply, yet the figured wood it yields may be just what a bowl-turner treasures.
D
The first method is the Timber Stand Improvement, or TSI, Cut. Here the poorest trees and plants are felled so that the space, light and other resources they used pass to the best stems still standing; removing invasive plants may be a second aim. Freed from crowding, the trees left behind can thicken, put out more foliage and spread wider crowns, giving better cover to wildlife and a greater chance of regenerating. A TSI Cut can be shaped to fit whatever an owner is trying to do with their land.
E
A Shelterwood Cut is possible only in a mature wood already thinned more than once. Once a new generation of seedlings has taken hold, the mature trees are removed together, letting the forester decide which species come up in their place and leaving a young stand whose trees are all at much the same stage of growth. It can also create a forest of two layers, yielding two harvests and stretching the owner's income across ten years or more.
F
A Salvage Cut, by contrast, tends to produce a great deal of low-use wood. Forests today face all manner of pests and diseases — the European spruce bark beetle, the large pine weevil, the nun moth and the pine-tree lappet moth are only a handful — and those who work among the trees can ease the pressure through well-judged felling. Such cuts thin out the sickened trees and check how far a pest may spread, while sparing the sturdy trees that came through the attack unharmed.
G
Thinning, and the clearing of dense or dead material to lessen the danger of wildfire, likewise yields low-use wood. Yet keeping back a certain amount of what most would write off as low-use wood matters greatly. Stripping it away is partly a way of taking off the fuel that a fire would burn; but when a tree is felled, its top is best left where it falls, so that the minerals locked inside it seep back into the earth. Trunks pitted with hollows are, likewise, priceless as homes for the creatures that prey on insects — woodpeckers, bats and other small mammals — which keep troublesome insect numbers down and make the forest healthier. Nor is every small tree low-use: some, such as the rowan, are a ready source of food for birds and other animals. And any species that is uncommon in a given wood should be left to grow, for it adds to the forest's structural variety.
Satellites, rocket shards and collision debris are creating major traffic risks in orbit around the planet. Researchers are working to reduce these threats.
A
A. In a single year, satellites are now launched at an extraordinary rate: military and civil agencies, private firms and even hobbyists together placed close to 500 in orbit, roughly five times the annual figure of the preceding decade. Should the biggest space firms act on plans to loft huge constellations — hundreds or thousands of satellites apiece — in the coming years, that total may climb far more steeply. Such crowding carries real danger. About a decade ago, a commercial American satellite, Aurora-6, collided with a dead Russian communications craft, Kometa-1408, and the impact scattered thousands of fresh fragments that now menace other spacecraft in low Earth orbit, the band of space reaching up to an altitude of 2,000 kilometres. In all, some 22,000 artificial objects are thought to circle the planet, from functioning satellites down to tiny scraps of rocket casing. Nor can operators dodge every looming collision, since each avoidance manoeuvre eats up time and propellant the satellite would otherwise devote to its actual mission.
B
Worry about orbital debris is nothing new — it dates to the earliest days of spaceflight — yet the population of objects overhead is climbing so fast that scientists are pursuing fresh approaches. One line of work aims to sharpen the techniques used to gauge what is actually up there, letting operators function more effectively in increasingly congested orbits. A number of groups have begun assembling an enormous database meant to hold the most reliable record of where each object sits. Elsewhere, other teams are drawing up classification schemes for debris, measuring characteristics like an object's size and shape so operators can judge how serious an approaching piece really is. To let matters slide, many argue, would be intolerable. A handful of unchecked collisions might throw off enough wreckage to trigger a self-sustaining chain reaction of fragments, leaving the region near Earth impossible to use. 'Carry on this way and we will pass a point from which there is no return,' warns Ingrid Halvorsen, an orbital-dynamics researcher at the Nordvik Institute of Astronautics in Bergen.
C
The number of objects aloft keeps growing even as our means of tracking them improve, and this has pushed firms, governments and other spacefarers into novel forms of cooperation against a shared danger. Bodies operating across borders — the Joint Orbital Debris Advisory Council among them — have put together recommendations aimed at protecting the long-term usability of orbital space. Under these, a satellite that has reached the end of its working life should be shut down, with any pressurised gas or leftover propellant that might trigger a blast vented off first. The same bodies also recommend easing retired craft far enough into the atmosphere for them to burn up within twenty years. Yet barely a third of all missions have honoured that twenty-year target, according to Tomasz Reinholt, who heads the orbital-debris office at the Pan-European Space Directorate in Vienna. Those planning the giant constellations insist they will behave as conscientious custodians of space, but Reinholt fears trouble may grow regardless of good intentions. 'And the ones that fold or go insolvent — what then?' he asks. 'They are hardly going to lay out money to pull their satellites back down.'
D
On paper, space is so vast that operators ought to have ample room to fly every one of these missions safely, never coming close to another object. With that in mind, some researchers are attacking the debris problem from the angle of location, seeking to establish exactly where every fragment lies. Pin that down, and most of the needless dodging now performed to head off possible collisions would no longer be necessary. 'Know precisely where everything is, and you would scarcely ever run into trouble,' says Diego Marchetti, a debris specialist with the Calderon Aerospace Institute in Arizona.
E
This area of work is known as space traffic management, precisely because it echoes the business of directing vehicles on roads or aircraft in the sky. Picture an airport on a hectic day, suggests Priya Anand, an astrodynamicist at Meridian University of Technology: aircraft queue up overhead, touching down and lifting off in close succession according to a tightly orchestrated plan. Controllers on the ground can fix each plane's position to within a single metre. No such precision exists for orbital debris, however. Many objects circling the Earth have never been catalogued at all, and even those that appear in databases are not followed with any consistency.
F
A further difficulty is the absence of any definitive catalogue setting out, with real accuracy, the orbits of every known piece of debris. Anand makes the point through a web-based tool of her own devising, which pulls together several feeds — among them the registries kept by the American and Russian governments — to map where objects sit. Type in the identifier for a given object and the tool traces a purple line marking its orbit. For some objects, though, the method falters: enter the code for one Russian rocket stage, listed as object 4471, and two purple lines appear at once, because the American and Russian feeds record wholly different orbits for that single body. Which of the two is right, Anand notes, is next to impossible to say, short of a third independent source against which the others could be checked. Anand calls herself a space environmentalist. 'My aim is to keep space safe to work in — open and useful for the generations still to come.' Until that goal is met, she contends, the community of spacefarers will keep sliding toward a tragedy in which every operator fouls a resource held in common.
High above a recently opened concert hall in the west of Rotterdam, what is said to be the world's largest rooftop farm has begun to yield its first crops. From tall plastic tubes tumble raspberries — small, deep red and remarkably full of flavour — their roots left dangling inside the hollow columns, dozens to a tube. Nearby, a second set of identical tubes sends out rows of spinach, and beside them sit fragrant herbs: basil, thyme and mint. Across the way, shallow trays filled not with earth but with coconut fibre hold cherry tomatoes, glossy peppers and deep-green kale.
It was on the roof of his own Rotterdam apartment block, a little over six years ago, that Joost Merckx — an engineer who also advises on sustainability — first began tinkering with vertical farming and the soil-free growing towers, known as aeroponic systems, that these plastic tubes form. The plot above the concert hall is far larger, covering some 12,000 square metres, about the size of a large city block. In a single day, the young farmers who look after it have already gathered 2,600 heads of spinach and 130 crates of raspberries. Once the other two-thirds of the space is planted, a staff of 25 will bring in as much as 800 kg of around 40 kinds of fruit and vegetables daily. 'Feeding an entire city this way is never going to happen, of course,' Merckx warns. 'The city puts real limits on what you can grow, and where. Still, if enough wasted space were converted like this, meeting five to ten per cent of the city's demand is not out of the question.'
What matters most, perhaps, is that all this serves as a working advertisement for Verdantis, Merckx's thriving urban-farming consultancy, which these days receives enquiries from every corner of the globe wanting help to design and build a new kind of soil-free city farm. He lists the benefits readily. 'It bothers me that the fruit and vegetables on our plates have usually been treated with as many as twenty different chemicals, and that the intensive methods behind them pour out greenhouse gases. It bothers me, too, that the average item has been trucked some 1,800 chilled kilometres before I eat it, that it tastes of little because the varieties were bred to survive long trips rather than to taste good, and that of every euro I hand over, roughly 80 per cent goes to distributors and haulage firms rather than the farmers.'
The soil-free approach, by contrast, needs nothing more than a modest flow of water, laced with organic nutrients and pushed endlessly around a sealed loop of pipes, towers and trays. 'The food is grown right here and sold just below us, so it hardly moves at all,' says Merckx. 'You can pick your varieties for their taste instead of their ability to survive weeks in transit, and you harvest them at their peak rather than ahead of it.' Because the roots are misted every ten minutes with water that is then captured and reused, no soil is worn out and the system gets by on 90 per cent less water than an ordinary intensive farm producing the same amount.
None of this makes urban farming itself a novelty. City agriculture is thriving everywhere from Singapore to Chicago and Seoul to Bangkok, with herbs raised in abandoned shipping containers and mushrooms in disused metro tunnels. The gear, Merckx notes approvingly, is light enough to sit on almost any level roof and costs little — somewhere between €90 and €140 for each square metre. Running it is cheap as well, since it draws only a small fraction of the power that some other methods demand.
Food produced in this way usually costs more than that from conventional intensive farms, though less than what soil-based organic growers charge. Naturally the technique has its boundaries, and a good deal of what it produces belongs to the warmer months. 'Root crops are still beyond us,' Merckx admits. 'Radishes are fine, but the long roots of carrots or potatoes rule them out, fruit trees are simply impossible, and beans swallow up space while giving back very little.' Even so, the sort of urban farming now under way in Rotterdam forms one piece of a larger, rapidly shifting picture, one that is drawing the growing of food ever closer to where we live.
B. Those markets are useful because they will take timber of a lower grade, and price, than any sawmill would consider. In Pennsylvania most wood burned for energy is turned into heat or electricity by combustion: many schools and hospitals run their heating on wood-chip boilers, countless homes rely on wood for warmth, and several power stations blend wood into the peat they burn for electricity. Wood can also be turned into gas for power, or processed into liquid fuels such as ethanol and petrol — the very fuels that drive lorries and cars. Every one of these products draws chiefly on low-use wood, and several cutting methods, each able to improve a forest's long-term quality, are built around supplying it.
C. Just how much any tree is 'worth', though, is far from fixed. It turns on a range of things — species, size, shape, condition, quality, the part it plays in the wood and how easily it can be reached — and on what the owner wants from the forest. The same tree may strike two people quite differently. To a timber merchant, a tall oak with a clean, straight trunk is a valuable saw-log or future furniture; to an owner who cares about wildlife, that trunk's worth lies in the food and shelter it gives animals. Likewise, once fungal decay — a defect foresters call heart-rot — has crept into a stem, its timber value drops sharply, yet the figured wood it yields may be just what a bowl-turner treasures.
D. The first method is the Timber Stand Improvement, or TSI, Cut. Here the poorest trees and plants are felled so that the space, light and other resources they used pass to the best stems still standing; removing invasive plants may be a second aim. Freed from crowding, the trees left behind can thicken, put out more foliage and spread wider crowns, giving better cover to wildlife and a greater chance of regenerating. A TSI Cut can be shaped to fit whatever an owner is trying to do with their land.
E. A Shelterwood Cut is possible only in a mature wood already thinned more than once. Once a new generation of seedlings has taken hold, the mature trees are removed together, letting the forester decide which species come up in their place and leaving a young stand whose trees are all at much the same stage of growth. It can also create a forest of two layers, yielding two harvests and stretching the owner's income across ten years or more.
F. A Salvage Cut, by contrast, tends to produce a great deal of low-use wood. Forests today face all manner of pests and diseases — the European spruce bark beetle, the large pine weevil, the nun moth and the pine-tree lappet moth are only a handful — and those who work among the trees can ease the pressure through well-judged felling. Such cuts thin out the sickened trees and check how far a pest may spread, while sparing the sturdy trees that came through the attack unharmed.
G. Thinning, and the clearing of dense or dead material to lessen the danger of wildfire, likewise yields low-use wood. Yet keeping back a certain amount of what most would write off as low-use wood matters greatly. Stripping it away is partly a way of taking off the fuel that a fire would burn; but when a tree is felled, its top is best left where it falls, so that the minerals locked inside it seep back into the earth. Trunks pitted with hollows are, likewise, priceless as homes for the creatures that prey on insects — woodpeckers, bats and other small mammals — which keep troublesome insect numbers down and make the forest healthier. Nor is every small tree low-use: some, such as the rowan, are a ready source of food for birds and other animals. And any species that is uncommon in a given wood should be left to grow, for it adds to the forest's structural variety.
B. Worry about orbital debris is nothing new — it dates to the earliest days of spaceflight — yet the population of objects overhead is climbing so fast that scientists are pursuing fresh approaches. One line of work aims to sharpen the techniques used to gauge what is actually up there, letting operators function more effectively in increasingly congested orbits. A number of groups have begun assembling an enormous database meant to hold the most reliable record of where each object sits. Elsewhere, other teams are drawing up classification schemes for debris, measuring characteristics like an object's size and shape so operators can judge how serious an approaching piece really is. To let matters slide, many argue, would be intolerable. A handful of unchecked collisions might throw off enough wreckage to trigger a self-sustaining chain reaction of fragments, leaving the region near Earth impossible to use. 'Carry on this way and we will pass a point from which there is no return,' warns Ingrid Halvorsen, an orbital-dynamics researcher at the Nordvik Institute of Astronautics in Bergen.
C. The number of objects aloft keeps growing even as our means of tracking them improve, and this has pushed firms, governments and other spacefarers into novel forms of cooperation against a shared danger. Bodies operating across borders — the Joint Orbital Debris Advisory Council among them — have put together recommendations aimed at protecting the long-term usability of orbital space. Under these, a satellite that has reached the end of its working life should be shut down, with any pressurised gas or leftover propellant that might trigger a blast vented off first. The same bodies also recommend easing retired craft far enough into the atmosphere for them to burn up within twenty years. Yet barely a third of all missions have honoured that twenty-year target, according to Tomasz Reinholt, who heads the orbital-debris office at the Pan-European Space Directorate in Vienna. Those planning the giant constellations insist they will behave as conscientious custodians of space, but Reinholt fears trouble may grow regardless of good intentions. 'And the ones that fold or go insolvent — what then?' he asks. 'They are hardly going to lay out money to pull their satellites back down.'
D. On paper, space is so vast that operators ought to have ample room to fly every one of these missions safely, never coming close to another object. With that in mind, some researchers are attacking the debris problem from the angle of location, seeking to establish exactly where every fragment lies. Pin that down, and most of the needless dodging now performed to head off possible collisions would no longer be necessary. 'Know precisely where everything is, and you would scarcely ever run into trouble,' says Diego Marchetti, a debris specialist with the Calderon Aerospace Institute in Arizona.
E. This area of work is known as space traffic management, precisely because it echoes the business of directing vehicles on roads or aircraft in the sky. Picture an airport on a hectic day, suggests Priya Anand, an astrodynamicist at Meridian University of Technology: aircraft queue up overhead, touching down and lifting off in close succession according to a tightly orchestrated plan. Controllers on the ground can fix each plane's position to within a single metre. No such precision exists for orbital debris, however. Many objects circling the Earth have never been catalogued at all, and even those that appear in databases are not followed with any consistency.
F. A further difficulty is the absence of any definitive catalogue setting out, with real accuracy, the orbits of every known piece of debris. Anand makes the point through a web-based tool of her own devising, which pulls together several feeds — among them the registries kept by the American and Russian governments — to map where objects sit. Type in the identifier for a given object and the tool traces a purple line marking its orbit. For some objects, though, the method falters: enter the code for one Russian rocket stage, listed as object 4471, and two purple lines appear at once, because the American and Russian feeds record wholly different orbits for that single body. Which of the two is right, Anand notes, is next to impossible to say, short of a third independent source against which the others could be checked. Anand calls herself a space environmentalist. 'My aim is to keep space safe to work in — open and useful for the generations still to come.' Until that goal is met, she contends, the community of spacefarers will keep sliding toward a tragedy in which every operator fouls a resource held in common.
