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February 10 has gone down in space history. For the first
February 10 has gone down in space history. For the first time, two man-made space vehicles, quite intact, "overtook" each other in orbit.

What is more, one of them, a U.S. communications satellite of the Iridium series, had no inkling of its imminent death until it crashed into a Russian communications spacecraft of the Kosmos series. True, the Russian party to this traffic incident had been out of operation for 10 years, and was just filling space.

Of course, something always happens for the first time. But in this case, it is better late than early. The incident, which has produced an additional amount of space debris, shows that unless we take prompt measures to keep heavily-trafficked space routes clean, there will soon be no room left either to travel or even just to pass.

But the public need not worry. Although there are 600 large fragments of former satellites in space, they pose no threat to the International Space Station or space shuttles. The smash-up occurred at an altitude of just under 800 kilometers. In such orbits, space junk can stay for decades without entering the denser atmosphere and falling on the Earth.

But some NASA experts believe that some of the fragments may have shifted to other orbits, higher or lower. So some of the small debris may be at the same altitude as the ISS, which is 350 kilometers.

A few words about "our heroes of the day." In practice, communications satellites are injected into a low, an intermediate or a stationary orbit. Their altitudes are 1,000 kilometers, 10,000 kilometers and 36,000 kilometers, respectively.

In geostationary orbit, a satellite makes one revolution around the Earth in 24 hours. Since the Earth completes one rotation around its axis at the same time, the satellite seems to be fixed above the equator. The main advantage of the geostationary orbit is that ground stations need not track satellites moving across the sky; it is only necessary to point the antenna at one spot throughout the entire service life of the satellite. A major disadvantage is a quarter-of-a-second delay between the time a radio signal is sent by one ground-based station and is received by another, created by the long distances the signal has to travel.

The main advantage of a lower Earth satellite is that a satellite does not require a powerful booster to reach it. Since the distance from the ground station to the satellite is shorter, satellite equipment can be less powerful. But craft in such orbits move relative to ground radio stations; and to ensure unbroken coverage, tracking antennas are needed and more than one satellite is required.

In the early 1990s, the West saw a rapid growth of the mobile communications market. Toward the end of the millennium, the United States came practically to dominate it. At the time, Iridium company set up a constellation of 20 satellites in low orbits, which ensured cellular mobile communications all over the globe. It was for the benefit of mobile telecommunications that the smashed U.S. satellite was working, after spending nearly 12 years in space.

Its Russian cousin belonged to the largest Soviet-Russian satellite series, Kosmos, which saw the light of day on March 16, 1962. Most of these spacecraft have served and are serving the interests of the Defense Ministry. The second party to the collision was no exception. Named Kosmos-2251 and launched on June 16, 1993, the satellite provided a special communication link for the Defense Ministry and had an orbit of 783 kilometers at its lowest point, 821 kilometers at its highest point, and an inclination of 74 degrees.

Now our two "heroes" have added to an ever-growing cloud of space litter, which no one knows how to deal with.

NASA's quarterly report issued last fall quotes truly shocking data. Today there are 12,851 large man-made objects circling the globe, including 3,190 operating and defunct satellites, and 9,661 spent rocket stages and other pieces of space junk.

The number of junk particles measuring between 1 and 10 centimeters is over 200,000, and that of particles smaller than 1 centimeter may surpass tens of millions.

Most of the space debris is concentrated at altitudes of between 850 and 1,500 kilometers, but large quantities are also found at altitudes used by spaceships and the ISS.

So far there are only two credible methods of preventing new space litter accumulating in near-Earth space. One is to deorbit fragments of boost vehicles by burning their remaining fuel. The second is to lift spacecraft that have served their purpose to burial orbits higher up. Specialists estimate that they can survive there for 200 years and more.

An international agreement banning the destruction of satellites in orbit, which is now in the works, can also contribute to cleaner space. Early in February, Alexander Boyarchuk, research director at the Russian Academy of Sciences' Astronomy Institute, reported that "work is under way to introduce a ban on satellite destruction so that no space debris accumulates."

In other words, it is high time we drafted, learned by heart and passed a test in space traffic rules.

The opinions expressed in this article are the author's and do not necessarily represent those of RIA Novosti.

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