Idle satellites, rockets and fuel tanks are only a part of the thousands of rubbish inertly circling the Earth. A total of several thousand tons of scrap metal fly over our heads.
Iridium 33 is an American satellite telephony that has been orbiting our orbit since 1997. After 12 years it has gone down in history, though probably not as its creators would have liked. On February 10, 2009, some 800 km above Siberia, it collided with the old Russian military satellite Kosmos 2251, which has been orbiting our planet for several years.
Thus, it was the first ever collision of two artificial Earth satellites. As the Iridium, weighing more than 560 kg, bumped into Russian machinery twice as heavy, thousands of larger and smaller debris were launched into space. We can only imagine what the collision must have looked like at a speed of over 27,000. km / h (the creators of the film “Gravity” let your imagination run wild).
Whether we like it or not, there will be more similar events. Over the past 70 years, that is, since humanity first sent its first satellite into space, the amount of debris circulating around our planet has started to reach a critical point. The European Space Agency warns that with today’s orbital littering, collisions between satellites will occur on average every 5-9 years.
The threat is real and it fascinates scientists from the industry more and more. It would seem that there is so much space in space that even a very large number of non-working satellites should fit easily. It turns out, however, that there are only a few preferred orbits, to which satellites most often travel, and they are starting to get crowded.
At the beginning of the conquest of space, there was no concern at all about its littering. It was believed that space objects would burn in the atmosphere. With time, however, it turned out that not everything burns in the atmosphere right away, and that hundreds of abandoned objects circulate around the Earth for years.
With over 3,000 There are only 700 satellites accompanying our planet. The most of them were launched into space by the Americans and the Russians. Most are communication or navigation satellites, others are used for Earth or weather observation. The remaining ones fly inertia, creating a threat, such as the Vanguard I launched into a medium orbit in 1958. It has not been connected with it since 1960 and remains the longest-lived garbage to this day.
Among the space junk, there are used multi-stage rockets, empty fuel tanks, and objects of much less weight. In 1965, the American astronaut Edward White lost, for example, a glove while leaving the Gemini 4 ship. Michael Collins lost his camera in space (a few years, by the way). In addition, we can come across the usual garbage that the Russians have been throwing from the Mir station for 15 years, an old toothbrush or a tool bag dropped in 2008 by the astronaut Heidemarie Stefanyshyn-Piper
The amount of space debris has not been precisely defined. Currently, about 17 thousand. objects large enough or distinctive enough to be detected. In practice, for low orbits, objects larger than a few centimeters are detected and observed. For medium and high orbits, the tracked objects must be at least 10-30 cm in size. In fact, the amount of space debris is probably around 30,000-40,000.
The American Space Command (AirForce Space Command) says it follows the flight path of about 22,000. debris of various sizes. The equipment currently in use allows the recognition of objects with a diameter greater than 5 cm in a low Earth orbit and with a diameter of about 50 cm in a geostationary orbit. The largest elements are visible even through an ordinary telescope.
Satellites like missiles
Nobody knows how many small pieces of cargo, about 1 cm in size, fly in space. Estimates range from 300,000. up to a million. In just 60 years, there were 200 large explosions that threw a cloud of skin fragments, screws and dozens of similar parts into space. Every now and then the scrap also bounces against each other, which results in the appearance of new elements.
The concentration of scrap metal around the Earth is so high that it is starting to threaten research expeditions and hinder space exploration. Most objects move at a speed of about 27,000. km / h, so a collision with even small litter can be very dangerous. If the velocities add up, energy will be released that is comparable to the force of an explosion of even a kilogram of TNT.
The increase in the amount of space debris mainly concerns the space above the poles of our planet. This is where the orbits of many satellites intersect, orbiting at an altitude of about 800 km. The natural period of deorbitation, the time remaining for combustion in the Earth’s atmosphere, is about 150 years for this altitude. Scientists have calculated that before this happens, the risk of collision with another satellite is up to 30%. If we do nothing, it will get even worse. The optimistic scenario assumes that over the next two centuries, the amount of space debris will increase by 19%. Pessimistic – that by 36%.
Not only unmanned satellites are at risk, but also people. The International Space Station (ISS) is primarily at risk. Of course, most large facilities are monitored on an ongoing basis and are simply moved out of the way, but sometimes unpredictable situations occur. Just a month after the aforementioned collision of two satellites in 2009, ISS astronauts had to evacuate to two capsules of Russian Soyuz ships due to debris approaching the station. The vehicles could disconnect from the ISS and return to Earth at any moment. Trash was located too late to dodge. Fortunately, the collision did not take place, but since then similar evacuations of astronauts have been carried out several times.
Space debris is a real threat also to people on Earth. Sometimes there are accidents where the scrap metal literally falls on people’s heads. This was the case of a woman in Turley, Oklahoma, who was struck by a 10 x 13 cm fragment in 1997. As it turned out, it was a fragment of the Delta II rocket launched a year earlier. Only by a miracle the woman did not suffer major injuries.
In the same year, a 270 kg fuel tank was dropped near Georgetown, Texas. Luckily, he missed anyone Relatively recently, because in March 2012, fragments of space debris also poured on people in the vicinity of the village of Otradnienskoye, located in the depths of the Siberian wastelands. The malicious say that we will only start cleaning up scrap in orbit when it begins to pose a threat to air traffic.
The question is why hasn’t this been done so far? The answer is prosaic – as always, it is about money. “Apart from the complexities that need to be worked out to get the garbage out of orbit, you need to use a comparable amount of energy to the amount spent to put it into space. This involves spending a lot of money. You have to fly to the object, capture it, and then change its speed so that the perigee of the orbit is low enough for the resistance of the atmosphere to do the rest.
Financial resources are mainly used to monitor the situation and theoretical studies. Conceptual work has been underway for years, dozens of scenarios and methods are being developed regarding the methods of intercepting and deorbiting garbage. In order to control the problem, a number of regulations were introduced to reduce the risk to objects in the most frequently used orbits. For example, in order to protect the geostationary orbit, it was established that the operator must ensure that at the end of its “life” the satellite moves into a resting orbit. The Ariane and Vega rockets used by ESA cannot carry a satellite into low orbit, the operator of which does not previously show that it will be deorbitated in no more than 25 years.
Since 2008, the European Space Agency (ESA) has been implementing an important Space Situational Awareness program, which concerns the detection, observation and tracking of space debris and asteroids that may threaten our planet. To a large extent, it allows for constant observation of scrap metal in the orbits. The Russian Space Agency (Roscosmos) is also working on the collision warning system with hazardous waste.
The Americans are also busy. As part of the US Air Force Space Fence program, the defense concern Lockheed Martin will build a radar to track space debris for 1.5 billion dollars. However, these are ad hoc measures and focus on avoiding the threat, not on eliminating it.
So far, the costs resulting from the problem of space debris have not exceeded the costs of their disposal, therefore there is no strong incentive to undertake intensive work in this field. However, time is working against us and sooner or later we will have to clean up the orbit to sustain the cosmic architecture we cannot live without.
As one country will not provide sufficient funds to get rid of space debris, only an international project has a chance of success.