Space Debris: Debris from the Recent Past

For the first time, scientists started talking about large-scale pollution of space in the 1980s, when the concentration of garbage in the Earth’s orbit reached such a density that the ballistics needed to work hard to safely place one or another satellite among it. In the last decade, the situation has only worsened. “The amount of garbage in the near-Earth space is so great that this creates a real danger for the automatic stations working there. In the near future, difficulties will increase like a snowball, ”believes Alexander Bagrov, senior researcher at the Institute of Astronomy of the Russian Academy of Sciences. The reasons for this are very serious.

Landfill in the sky - trouble on Earth

First of all, objects in orbit suffer from space debris. “Ground-based surveillance services sometimes record collisions of space debris particles with each other, because of which their number multiplies exponentially, ” says the chairman of the commission on space debris problems of the Russian Academy of Sciences, deputy director of the Institute of Applied Mathematics named after Keldysh Efraim Akim. - Fine fractions are no less dangerous than large fractions. Just imagine a large-caliber bullet moving at a speed of 8-10 km / s. When such a particle enters an operating spacecraft, the collision force is simply monstrous. No ship can withstand such a collision. If a collision occurs, a cloud of debris in orbit will spread in all directions in just a couple of weeks, threatening to destroy other neighbors. ”

The crater on the glass of the shuttle porthole Endeavor arose as a result of the impact of a microparticle of space debris, crashing at high speed into the ship.

And although the probability of the orbiting satellites crashing by space debris is still extremely small, there have already been unpleasant incidents, including with manned spacecraft and orbital stations.

In 1983, the crew of the infamous Challenger shuttle discovered on the windshield of their ship a small trace of a collision with a foreign object. The crater was only 2.5 mm deep and the same width wide, but made NASA engineers very worried. After the landing of the ship, the specialists carefully examined the damage and came to the conclusion that the cause of the collision was a microparticle of paint, exfoliated from some other spacecraft. The Soviet orbital station Salyut-7, whose surface was literally dotted with microscopic craters from collision with debris particles, also suffered from space debris. To prevent the possibility of such incidents in the future, the Mir station and the ISS that replaced it were equipped with screens that protected the inhabited modules from collisions with small debris. However, this did not help either. In June 1999, the then uninhabited ISS had every chance of colliding with a fragment of the upper stage of one of the rockets, which had been orbiting the Earth for many years. Fortunately, the specialists of the Russian Mission Control Center (MCC) managed to correct its orbit in a timely manner, and the chip flew past at a distance of 6.5 km. In 2001, the ISS had to take a special maneuver in order not to collide with a seven-kilogram instrument lost by American astronauts during their spacewalk. Since then, the station has been dodging space debris with enviable regularity, several times a year.

Trash Cake Space debris has been well studied to date. As scientists note, it is distributed in orbits in layers, like the filling of a pie. This is directly related to the functional load on one or another orbit. The more convenient it is, the more satellites work on it. After some time, some of them turn into lifeless scrap metal, which pollutes the space in which their life has recently passed. The first belt of garbage is located at an altitude of 850−1200 km from the surface of the Earth. It is here that a huge number of meteorological, military, scientific satellites and probes are moving. The second pollution belt lies in the region of geostationary orbits (over 30 thousand km). Now there are about 800 objects of different countries. Each year, 20–30 new stations join them.

Space debris is also dangerous for earthlings far from space, falling on their heads in the literal sense of the word. In 1978, taiga regions in northern Canada were affected by the fall of the Soviet satellite Cosmos-594. A year later, the wreckage of the American space station Skylab scattered over the desert regions of Australia.

In 1964, during the unsuccessful launch of a US navigation satellite with nuclear energy sources on board, radioactive materials scattered over the Indian Ocean. Everyone remembers the situation with the Mir station, flooded in the Pacific Ocean. Then tens of thousands of inhabitants of island states experienced a form of mass psychosis. People were panicky afraid that the "Russian whopper" would fall on their heads. But for residents of the Altai Territory, this nightmare has become a reality. It is over this region of Russia that the flight paths of missiles launched from Baikonur lie, and it is here that the debris of the first stages with the remnants of highly toxic fuel lie.

But what is space debris? Where does he come from?

Who is littering here?

“The situation is paradoxical, ” said Alexander Bagrov. “The more we launch vehicles into space, the less usable it becomes.” Indeed, according to Russian experts, there are currently more than 10 thousand aircraft and Earth satellites in space, with only 6% of them functioning. Spacecraft fail with enviable regularity, and as a result, the density of space debris in orbit increases by 4% annually. Currently, about 70-150 thousand objects from 1 to 10 cm in size revolve around our planet, while millions of particles are less than 1 cm in diameter. “And if in low orbits up to about 400 km, debris slows down to the upper atmosphere and eventually falls to the Earth, then in geostationary orbits it can rotate infinitely long, ” continues Alexander Bagrov.

Accelerating space debris is also being contributed by booster rockets, with the help of which satellites are launched into geostationary orbits. About 5-10% of the fuel remains in their tanks, which is very volatile and easily turns into steam, which often leads to powerful explosions. After several years of being in space, the spent rocket stages scatter into pieces, scattering small shrapnel around them. In recent years, 182 similar fireworks were recorded in near-Earth space. Only one recent explosion of a stage of the Indian launch vehicle led to the formation of 300 large fragments and countless small, but no less dangerous objects. The first victims were already.

The near future: the spent space stations and communication satellites will begin to fall on the heads of earthlings.

In July 1996, at an altitude of approximately 660 km, the French satellite collided with a fragment of the third stage of the French Arian rocket, launched much earlier. The relative speed during the collision was about 15 km / s, or about 50, 000 km / h. French ballistics, missed the orbit of their own large object, then bit their elbows for a long time, and there was nothing. The incident did not end with a major international scandal just because both sites were of French origin. How to clear orbit of space debris?

Space Scavenger Vacancy Still Open

“Unfortunately, at the moment there are no effective ways to destroy space debris, ” said Efraim Akim. In his opinion, collecting debris with the help of American shuttles is insanely expensive, and shuttles have been joking for several years now. It’s even more crazy to burn space debris with a laser, as molten metal cools down into a deadly “shrapnel” that spreads in orbit, further polluting the cosmos. Replacing multi-stage missiles with reusable systems is also not yet possible, they are too expensive. “Of course, it's good to launch and pick up satellites using flying saucers. At any moment it took off, hooked it and sat back to Earth, - laughs Efraim Akim. - Alas, humanity does not have such technical devices. Until they appear, we need to do our utmost to prevent further space pollution, otherwise in the future, because of the danger of meeting space debris, its development will turn into a very risky event. "

The only thing that scientists can offer so far is a thorough mapping of the space dump. But here everything is not so simple. “Today, only two states in the world are able to effectively monitor the behavior of space debris, ” said Nikolai Ivanov, chief ballistic officer of the MCC. It is easy to guess that these are Russia and the USA, which, by the way, are the main “polluters” of space. “We, like in America, have unique ground-based complexes that allow us to detect pieces in low orbits up to several centimeters in diameter, but it is also necessary to jointly develop measures to neutralize them. It would be nice to create an international tracking system, combine catalogs of objects, develop a common warning system about collision risks, only in this case you can really secure flights, ”Nikolai Ivanov continues. “In order to avoid accidents on space roads, it is necessary to develop international rules for space movement, ” Efraim Akim echoes. The first steps in this direction have already been taken.

The language of numbers According to the Russian Academy of Sciences (RAS), about 85%. space debris falls on the share of large parts of rockets and booster blocks, with the help of which artificial Earth satellites are put into orbit, as well as spent satellites themselves. Another 12% of garbage is structural elements that separate during the launch of satellites and their operation. All the rest is small fractions and fragments resulting from their collision.

Space traffic rules

“Several international commissions, including under the auspices of the United Nations, are engaged in the prevention of further pollution of outer space, ” says Alexander Alferov, scientific secretary of the Space Council of the Russian Academy of Sciences. - True, they are faced with the slowness of a number of agencies that prefer to weigh everything very carefully before going for cooperation. The fact is that many satellites belong to the military departments and it is very difficult to obtain complete information about them. You can not discount the commercial side of the issue. ” However, the privatization of space plays into the hands of those who advocate for its purity. “Cosmos is gradually turning into a zone of capital investment, and traders have always been interested in issues of risk insurance and compensation for losses as a result of certain force majeure circumstances, ” said Alexander Bagrov. - Without the development of uniform legal norms, this cannot be achieved. For example, who should answer if an old lifeless satellite or a booster rocket launched by one state rams an automatic station belonging to another country? There is no answer to this question yet, although similar precedents have already taken place. ” And although private space companies are only taking their first steps, the very fact of their birth prompted the development of uniform international rules. “At present, new requirements for space technology are being intensively developed, satellite operating zones are being determined, and the methods for burying the vehicles that have reached their term are being negotiated, ” says Efraim Akim.

One of the first real achievements in the fight against space debris was the development of new international standards for artificial Earth satellites. Now on board their reserves of fuel should be present, so that at the end of their working life the vehicles will be taken to specially designated areas of near-Earth orbits or sent to the Earth. It is also advisable to equip the satellites with additional control systems that can, in the event of an apparatus hit by debris particles, remove it from working orbits. It is assumed that “satellite cemeteries” will be located 200-300 km above the geostationary orbit zone. “Of course, the implementation of new standards is very slow, ” admits Efraim Akim, “because they are associated with significant costs. A change in satellite design entails additional multi-million dollar investments, which not all aerospace corporations like. But at the moment we simply cannot do without these measures, and everyone understands this. ”

Another important step is the introduction into the international space use regulations of the requirement to equip booster blocks of rockets with fuel drain systems. Once in space, after the completion of the maneuver, the control electronics must open the valves and throw away excess fuel. Unfortunately, this is sometimes not enough. Due to the nature of the fuel and the inability to completely throw it out of the tanks, even “empty” tanks explode. So, measures must be taken to improve the design of space rockets.

The article was published in the journal Popular Mechanics (No. 7, July 2006).


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