Russians ask whether Earth will share the fate of Saturn
ROSAVIAKOSMOS NEWS RELEASE
Posted: May 12, 2001
Is it possible that space exploration will result in the formation of a ring around the Earth similar to the Saturn ring? Most likely human beings will not be able to create such a dense object. However, all this debris can severely impede space flights in future, as plenty of objects brought out into space would stay in the near-earth orbit for hundreds and even thousands of years. Therefore, Russian scientists believe that the spaceships design needs urgent modifications to ensure their return to the Earth.
The fate of an object in space depends on the altitude it is located at. Space stations rotate [sic] at the height of 400-500 kilometers. The atmosphere still exists there and it slows down an object. The object looses its speed and within a couple of years enters dense atmospheric layers where it fully burns out. A lot of objects happen to rotate beyond the atmosphere. The scientists have found out two peak altitudes the objects are concentrated at about 800 and 1500 kilometers. Another group of objects is located in the geostationary orbits -- about 36 thousand kilometers above the Earth surface.
As there is no atmosphere to affect flights there, the object will continue to rotate around our planet for a long time. The objects concentration there is accountable -- it is at these heights that various communication satellites and other useful devices are located. The more objects are in orbit, the higher the risk of collisions is.
During the 40-year period of active space research an operating satellite once has happened to collide with a large object, resulting in the loss of the French space satellite. "Mir" station and American "Shuttle" spaceships have undertaken several maneuvers to avoid the clashes. Even the International Space station that is not fully operational yet has already conducted an escape maneuver. However, in terms of flight safety the risk of a dangerous collision with a space object is very high: for a single operational module of this station it makes 5-10% within the 15-year estimated operation period.
Generally, space debris can be divided into two categories: the objects, which can be seen through a telescope and the objects too small for regular observations. It is easier to work with the first category (the objects being more than 20 centimeters in size) because they are registered in the catalogues, their number slightly exceeding 8,500. Half of these objects were created as a result of satellite and carrier rocket destruction. Astronomers have altogether recorded more than 150 explosions in space.
The debris that can not be seen through a telescope is more difficult to deal with. Its particles sizing millimeters and flying at the speed of 10 kilometers per hour are capable to damage a satellite or a space station: spoil a solar battery or, even worse, to make a hole in a fuel tank. But these particles are incalculable. Therefore the scientists are developing simulators which allow to forecast the behavior of such small objects. The countries involved provide for different simulators, the computation results varying by dozens of times. Our scientists consider these variations to be acceptable, such deviations are quite insignificant when computing millions of objects, particularly millimetric debris particles flying in the near-earth orbit.
Applying their model, the specialists from the Center for Space Observations (Rosaviakosmos) have investigated future development of the near-earth space pollution process. They have reviewed five scenarios:
It has appeared that in case of scenarios 1-3 the debris volume in orbit will grow up by 2-3 times by the 22nd century. Provided all the above steps are implemented (the number of explosions goes down and all flying objects return to the Earth), this will allow to reduce the debris volume by 1.5 times within the next hundred years. Foreign scientists have made similar conclusions.
Therefore, the March meeting of the International Committee on Space Contamination adopted a resolution on the necessity to bring order to the near-earth-space. The space flight standards for all countries should include a requirement for the space devices developers to ensure the objects return from the orbit.
Unfortunately, there is no quick way to achieve it, because this entails immediate expenses growth. First of all, it is necessary to change the carrier rockets design so that the waste stages descended to the lower orbits. Secondly, additional fuel will be needed for each satellite to allow its descend to the atmosphere. However, the space pollution is close to critical, so these expenses appear to be unavoidable.
The Hubble Space Telescope's majestic view of the Eskimo Nebula. This spectacular poster is available now from the Astronomy Now Store.