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Post Info TOPIC: Satellite collisions
Blobrana


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RE: Satellite collisions
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Computers Show New Strategies To Avoid Satellite Collisions

Orbiting satellites collect and relay vast amounts of data critically needed for civil, commercial, scientific, and national security applications. The USA and many other countries depend on space-based systems to navigate, communicate, monitor environmental changes, and provide surveillance data. Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory, Sandia National Laboratories, and the Air Force Research Laboratory are collaborating to improve capabilities for detecting and monitoring space debris and other threats to space operations. Since 2008, a team of computational physics and engineering experts at LLNL has been designing a comprehensive set of analysis, modelling, simulation, and visualisation tools called the Testbed Environment for Space Situational Awareness (TESSA).
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Blobrana


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The U.S. military said on Tuesday it is now tracking 800 manoeuvrable satellites on a daily basis for possible collisions and expects to add 500 more non-manoeuvring satellites by year's end.
The U.S. Air Force began upgrading its ability to predict possible collisions in space after a dead Russian military communications satellite and a commercial U.S. satellite owned by Iridium collided on Feb. 10.
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Blobrana


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Cosmos 2251 was an ordinary satellite designed to transmit signals across the vast Russian landmass. Launched in 1993, it would appear every 90 minutes or so over the northern skies, relay electronic blips of information among a network of satellites and ground stations like a hockey player passing the puck, and disappear over the southern horizon.
Iridium 33, launched for Motorola in 1997, did something similar, though it took a slightly different orbit that brought it closest to Earth during its pass over North America. For years the two satellites circled the planet, minding their own business, never coming within a thousand kilometres of one another.
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Blobrana


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The first catalogued fragments of shattered satellite Cosmos 2251 are about to reenter Earth's atmosphere. According to US Strategic Command tracking data, reentries will occur on March 12th, 28th and 30th, followed by more in April. Radar cross sections are not available for all of the reentering pieces; they are probably centimetre-class fragments that pose no threat to people on the ground.

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Blobrana


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The following advisory has been issued by the FAA.

FDC 9/5774 FDC .. SPECIAL NOTICE .. EFFECTIVE IMMEDIATELY UNTIL FURTHER NOTICE. AIRCRAFT ARE ADVISED THAT A POTENTIAL HAZARD MAY OCCUR DUE TO REENTRY OF SATELLITE DEBRIS INTO THE EARTHS ATMOSPHERE. FURTHER NOTAMS WILL BE ISSUED IF MORE INFORMATION BECOMES AVAILABLE. IN THE INTEREST OF FLIGHT SAFETY, IT IS CRITICAL THAT ALL PILOTS/FLIGHT CREW MEMBERS REPORT ANY OBSERVED FALLING SPACE DEBRIS TO THE APPROPRIATE ATC FACILITY TO INCLUDE POSITION, ALTITUDE, TIME, AND DIRECTION OF DEBRIS OBSERVED. FAA HEADQUARTERS, AIR TRAFFIC SYSTEMS OPERATIONS SECURITY

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Blobrana


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Space weapons are dangerous - but out-of-control, defunct satellites can do just as much damage, if not more.
So says a leading space scientist who has calculated that Tuesday's collision between an Iridium communications satellite and the defunct Soviet-era Cosmos 2251 spacecraft expended a great deal more destructive energy than China's infamous anti-satellite missile test did in January 2007.

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Blobrana


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The collision between U.S. and Russian communication satellites this week - the first such crash in space - has created speeding clouds of debris that threaten other unmanned spacecraft in nearby orbits, Russian officials and experts said Thursday.
The smash-up 800 kilometres over Siberia on Tuesday involved a derelict Russian spacecraft designed for military communications and a working U.S. Iridium satellite, which serves commercial customers as well as the U.S. Department of Defence.
In a statement Thursday, Iridium, based in Bethesda, Maryland, denied that it was responsible for the crash. The collision scattered space debris in orbits 500 to 1,300 kilometres above Earth, according to Maj.-Gen. Alexander Yakushin, chief of staff for the Russian military's Space Forces.

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Blobrana


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Space Junk
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Plans to spring-clean space junk orbiting Earth could result in the loss of irreplaceable historical artefacts, an archaeologist warns.

Dr Alice Gorman of Flinders University in Adelaide, an Australian researcher who has previously called for space junk to be World Heritage listed, is on a mission to preserve what she says are heritage items in space.
She plans to take that mission to the Australian Space Development Conference in Canberra in July and to the World Archaeological Congress in Jamaica next year.
Gorman says as space agencies prepare to de-clutter potentially dangerous space junk, it's time to assess the value of some of the millions of objects currently orbiting Earth.

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Blobrana


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More than 9,000 pieces of space debris are orbiting the Earth, a hazard that can only be expected to get worse in the next few years. And currently there's no workable and economic way to clean up the mess.

The pieces of space junk measuring 4 inches or more total some 5,500 tons, according to a report by NASA scientists J.-C. Liou and N. L. Johnson in 20th January 2006 issue of the journal Science.

Much of the debris results from explosions of satellites, especially old upper stages left in orbit.
The junk can pose a risk to commercial and research flights and other space activities.


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Blobrana


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Satellite collisions
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The U.S. Space Surveillance Network (SSN) has identified two accidental collisions between orbiting satellites.
One recent collision occurred in January 17 2005, while the other is a much older event which occurred in 1991 but has just now been recognized.
The recent collision involved a 31- year-old U.S. rocket body (1974-015B) and a fragment (1999-057CV) from the third stage of a Chinese CZ-4 launch vehicle, which exploded in March 2000.
The event occurred at an altitude of 885 km above Antarctica.



The other recently recognized collision of late December 1991 involved a Russian non-functional navigation satellite, Cosmos 1934 and a piece of debris from Cosmos 926. Both objects were in similar orbits with a mean altitude of 980 km.
As the number of objects in Earth orbit increases, the likelihood of accidental collisions in the future will also increase. Currently, hundreds of close approaches occur on a daily basis.
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