Space clean-up
A
AWhen the Soviet Union successfully launched Sputnik 1 in 1957, it was the first artificial satellite ever to enter orbit around the Earth, and the project's success marked a significant milestone in the history of the exploration of space. There was suddenly a profound change in human perspective, a change which would, in subsequent years, become ever more marked as scientists progressively acquired the ability to study aspects of the planet from a new (and not Earth-bound) point of view. However, the technology employed on that first satellite mission was astoundingly simple when compared to what would follow. To cite just one example of this, Sputnik 1 only employed four very basic radio transmitters. Commercial satellites in 2017 routinely employ dozens of extremely complex ‘transponders’.
B
BIncreasing use of ever-more sophisticated satellites has now permeated almost all aspects of modern life. Telecommunications could not function without them, and neither could the precision geo-location and navigational aids which we all take for granted. Worldwide monitoring of weather patterns has produced not only better forecasting, but an awareness of the human impact on the planet. Satellite imaging of the Earth is essential in conflict resolution and disaster management. Other satellites, such as the Hubble space telescope, are being used to collect data which help us understand the universe beyond our planet. Indeed, the international space station, on which a constantly changing crew of astronauts live, is another type of satellite.
C
CWhilst the use of satellite technology has had a far-reaching impact on our lives, the question remains of what happens to these machines when they are no longer functional. In total over 6,600 satellites have been launched since Sputnik 1. Of the estimated 3,600 which are still in Earth’s orbit, only 1,000 remain in operation with the rest having become lifeless space debris. The problem of space debris is also self-perpetuating; when two satellites collide, many more pieces of rubbish are produced. A recent collision between two relatively small satellites created over 2,000 trackable pieces. There are now tens of thousands of objects larger than 5cm in diameter in orbit and an estimated one hundred million man-made pieces larger than 1mm. This ever-growing volume of junk is referred to as the Kessler syndrome, whereby each collision creates ever more debris, increasing chances of further collisions.
D
DThis growing volume of space waste can have serious consequences. Debris hurtling through space can strike working satellites, rendering them inoperable. Not only is this incredibly costly, but it can also take entire communications or tracking networks offline. The danger increases with the involvement of manned spacecraft. In 2007, a piece of space debris pierced the radiator of US space shuttle Endeavour. The International Space Station has also faced problems. Despite being in an orbit with relatively little space debris, it is frequently forced to make time-consuming manoeuvres out of the path of fragments of rubbish. As a result, it is essential that pieces of space debris are constantly tracked. When they do not have the necessary three days’ warning to change the craft’s path, the crew members are increasingly told to take shelter in Soyuz, the evacuation craft.
E
EWith more satellites and spacecraft being launched every year, the problem of space debris needs a solution, one of which has recently been trialled by the Japanese. At the end of 2016, Kyoritsu was taken into orbit and released. Kyoritsu is a type of satellite from which a kilometre-long cable manufactured by a fishing net company is tethered to a 20-kilogram mass. As this moves through the Earth’s magnetic field, it generates an electric current which slows down space debris it comes into contact with. When travelling at a slower speed the debris is forced down into the Earth’s atmosphere where it burns up and is destroyed upon falling to Earth. Although the initial trial of Kyoritsu was unsuccessful as the tether failed to deploy, the team are hopeful for its future use.
F
FA further solution may come in redesigning both the types of satellites we use and the technology to retrieve them. As technology has improved, we have the opportunity to create much more compact satellites with considerably lower deployment costs. Many scientists worry that this will lead to a proliferation of debris as these smaller devices fall out of service. However, when Switzerland recently launched their first satellites, which were no larger than a briefcase, they understood the need to have a system in place to avoid them ending their life cycle as space debris. It is for this reason that they designed CleanSpace 1, a satellite with a cone-shaped net at the front which can unfold and then entrap smaller satellites. Once its targets have been captured, it can then slow down and de-orbit, burning everything up as it re-enters the atmosphere. CleanSpace 1 is scheduled to launch in 2018 to recapture the Swiss satellites.
G
GBrian Weeden, a technical advisor for the Secure World Foundation, has suggested that space debris was a ‘super wicked problem’. Super wicked problems are complex issues without any clear solution, and little time to find one. This is not helped by the fact that no central organisation takes responsibility. However, there are signs that more people are taking this issue seriously with both commercial and national space organisations understanding the need for sustainability in satellite deployment. Technologies like Kyoritsu and CleanSpace 1 are being developed but more programmes are needed. At present, Kessler syndrome still poses a real threat and the volume of space debris is growing.
Kéo chỉnh
Question 1 - 7
Which paragraph contains the following information? NB You may use any letter more than once.
A
B
C
D
E
F
G
1.
Satellites being smaller and cheaper to launch than they used to be.
2.
The fact that the more rubbish there is in space, the more is created.
3.
Space junk orbiting more slowly if it comes into contact with electricity.
4.
Some paths round the Earth containing less debris than others.
5.
Satellites performing a wide range of functions.
6.
Space junk being an issue that must be addressed with extreme urgency.
7.
Astronauts facing delays and dangers as a result of space debris.