Thursday, April 25, 2013

In space that threatens "total breakdown" by satellite - THE WORLD


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Crash in Space: The first major cosmic

In general, the threat of “total separation” of satellites

space junk is the serious danger if he is not eliminated. On some trajectories of space threatened with closure. Heiner ratchet wheel, an expert on space debris, warns of the consequences.

space junk is the serious danger if he is not eliminated. On some trajectories of space threatened with closure. Heiner ratchet wheel, an expert on space debris, warns of the consequences. From


At a conference in Darmstadt discussed in the past four days, 300 international experts on what are the strategies to deal with space debris. If nothing happens, the debris may cause damage in the universe is of the order of 100 billion euros. Guido Meyer spoke to the head of the Space Debris Office of the European Space Agency (Esa), Heiner ratchet wheel.

the world: It means that the orbit is full of rubbish – where exactly is this space junk


Heiner ratchet wheel: Most scrap there in the near-Earth region, ie at altitudes up to 2000 kilometers. There again it is between 700 km and 1000 km to the largest garbage collections. But also on tracks that are over the equator strongly inclined because they lead, for example, over the poles, residues have accumulated in the last decades.

the world: What is the geostationary orbit, using the primarily weather and communications satellites


ratchet wheel: Further away from Earth in approximately 36,000 kilometers above the concentrations are not so critical that one in the near future have to worry about cascade effect, as is predicted for the near-Earth space – so that retired satellites collide with others and thus creates new space debris, which in turn collide with other residues


the world: How do you know which scrap what size where the Earth orbits


ratchet wheel: Our data based on track measurements of an American space surveillance system, the Space Surveillance Network (SSN). This network creates data for about 16,000 objects orbiting the Earth. Furthermore, there are still 6000 more fragments that are tracked by this system. But about it we have at the moment no more accurate information because these objects have not yet been identified and therefore their original path is unknown.

the world: What damage could cause debris such as


ratchet wheel: Objects of only ten centimeters size would cause a catastrophic breakdown in a collision with other objects, even for large satellites. And when I speak of “total separation”, I mean that a satellite to be done centrally, not only out of action set, but is broken down into its component parts. Typically, one would expect to several thousand fragments in a collision of two intact objects. The last time we experienced in 2009, when the still functional “Iridium 33″ collided with the Russian satellite “Cosmos 2251″ satellites. For this clash 2,000 new pieces of debris have emerged. These are collisions that we should avoid in the future

the world: If even smaller objects are also at risk from


ratchet wheel: If you go down to one centimeter in size, we are talking of about 750,000 pieces of debris. Such an object would a normal satellite, if it is because a key hit, at least make it inoperable. In addition, about 160 million objects of approximately one millimeter in size. And even those might damage sensitive system components on the outer skin of a satellite sustainable and to interfere with the mission.

the world: What is the danger of the “International Space Station” (ISS)


ratchet wheel: The “ISS” moves in a very low orbit of less than 400 km in height. This region is not compromised because the remaining air resistance there is still so high that debris residing there, are relatively quickly washed out from the air resistance, so fall back to earth. The “ISS” has made an evasive maneuver to two per year on average in the past. This is comparable to the frequency, which we have also satellites are smaller. And if we have the same dodge rate, this means that the concentration in other rail heights of objects must be correspondingly higher. In the “ISS” the evasive maneuvers are the only reason why so often because it is so big. Their individual modules are also provided with a protective layer, which objects can catch up to a centimeter size.

the world: Are there opportunities for the future, to avoid space junk


ratchet wheel: Of course. Such mitigation measures include, first, that many objects are not unnecessarily dismisses in the suspension of a satellite into space, so you do not throw away any lens cover or engine covers. Moreover, nowadays trying to avoid explosions, both during the mission of a satellite and the end of its lifetime. This is done by then discharges the rest can burn or fuel from the engines. Finally, the on-board batteries are discharged, as this can sometimes explode.

the world: What are the chances that collisions can be avoided in the future


ratchet wheel: This works only with operational satellites, which are therefore still functional and thus controllable. Could avoid. Most newer satellites now have a fuel reservoir, to perform evasive maneuvers during the mission period can. We have flown in 2009 with our Satellite nine such evasive maneuvers.

the world: Is it possible to also retired satellites controlled crash


ratchet wheel: The requirement is that near-Earth satellite mission to the end, after more than 25 years, plunge into the atmosphere and burn there are. This can be achieved as with the development of sails or other large surfaces which increase the air resistance and thus the braking of the residual atmosphere. This unfolding of surfaces are thought to lower the car faster, so that one is immersed within the last 25 years in the atmosphere. Another option would be to attach to no longer operational satellites, an electrically conductive cable. This would have to be several kilometers long. It sat under the satellite would be pulled along by this and would like orient towards its center. This would cut through the magnetic field lines of the earth and so act as an electric generator. As a result, a current is induced in the rope, which produces an artificial resistance brings the objects even relatively high web heights to crash.

the world: Are there any plans to clean up and collect the trash once


ratchet wheel: Yes, there are different concepts. It could be an unmanned probe to dock to a disused satellite automatically. The drive system of the probe would then bring both the probe and the satellite to crash. Then there is the concept, a rope, a network or a harpoon at a defunct satellite to install. Even so, the captured objects could be made to crash. Alternatively, the probe could pull up to the geostationary orbit, where the satellite will revolve around the so-called graveyard orbit the earth forever without colliding with anyone or anything.

the world: Why are such concepts have not yet been implemented


ratchet wheel: Such a system could probably build within ten years, as the industry has assured us. However, you would need the financial resources and a legal protection. Because each object has an owner quasi temple. And it really is only with the owner to do something with this object. But unfortunately it is not that the countries that have contributed the most to pollution, such as Russia and the United States, will also be those who clean up first. These legal issues can probably be solved only by the United Nations.

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Photo: Esa Heiner ratchet wheel, head of ESA’s Office of Space residues

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