All about outer space garbageHave you ever tried to think of outer space garbage or space debris? These are man-made junks or collection of objects in orbit around the Earth that no longer serve any useful purpose at all. Other terms for these are space junks, orbital debris and space waste. These junks consist of everything from spent rocket stages and defunct satellites to fragments from collision, explosion and erosion. Debris is a potential collision risk to operational spacecraft as the orbits of these objects often overlap the trajectories of newer objects.
A report in 2011 by the National Research Council in the USA warned NASA that the amount of space debris orbiting the Earth was at critical level. Some computer models revealed that the amount of space debris "has reached a tipping point, with enough currently in orbit to continually collide and create even more debris, raising the risk of spacecraft failures". The report has called for international regulations to limit debris and research into disposing of the debris.
|Mir solar panels|
Every manned mission, space probe and satellite has the potential to create space junks. Any impact between two objects with considerable size of mass can create flakes of materials and shrapnel debris from the force of collision that can cause further damage, creating even more space debris. With a large enough collision such as one between a space station and a defunct satellite, the amount of cascading debris could be enough to render Low Earth Orbit essentially unusable.
Orbital decay takes much longer at higher altitudes where atmospheric drag is less significant. The slight atmospheric drag and solar radiation pressure can gradually bring debris down to lower altitudes where it decays.
What are the sources of debris?
- dead spacecraft
- lost equipment while in a outer space mission
- boosters - upper stages of a space shuttle, start and end their productive lives in orbit
- debris from and as a weapon - caused by testing of anti-satellite weapons
Larger objects or space debris can reach the ground intact and present a risk although most of it will just burn up in the atmosphere.
The original re-entry plan for Skylab called for the station to remain in space for 8 to 10 years after its final mission in February 1974. Unexpectedly high solar activity expanded the upper atmosphere resulting in higher than expected drag on space station bringing its orbit closer to Earth than planned. On 11 July 1979, Skylab re-entered the Earth's atmosphere and disintegrated, raining debris harmlessly along a path extending over the southern Indian Ocean and sparsely populated areas of Western Australia.
Saudi officials inspect a crashed
PAM-D module, January 2001.
On 27 March 2007, wreckage from a Russian spy satellite was spotted by Lan Chile (LAN Airlines) in an Airbus A340, which was travelling between Santiago, Chile, and Auckland, New Zealand carrying 270 passengers. The pilot estimated the debris was within 8 km of the aircraft, and he reported hearing the sonic boom as it passed. The aircraft was flying over the Pacific Ocean, which is considered one of the safest places in the world for a satellite to come down because of its large areas of uninhabited water.
Dealing with debris
Man-made space debris have been dropping out of orbit at an average rate of about one object per day for the past 50 years. Substantial variation in the average rate occurs as a result of the 11-year solar activity cycle, averaging closer to three objects per day at solar max due to the heating, and resultant expansion, of the Earth's atmosphere. At solar min, five and one-half years later, the rate averages about one every three days.
Taking out the trash in space
Astronaut Clay Anderson, who took care of the hoisting, told Mission Control, "I will be sending my bill in the mail — space trash disposal." Anderson is on the first spacewalk of his career and he clearly had a blast tossing first an unwanted 212-pound camera mount, then a 1,300-pound ammonia tank.
Perched on the end of the space station's fully extended robot arm, Anderson tossed the unwanted equipment into space as the station orbited 220 miles above the south Atlantic Ocean.
The numbers are staggering: 13,000 pieces of junk, each of them more than 30 feet long, are orbiting in space.
There are at least an additional 100,000 hunks of junk that measure between one and 10 centimeters — roughly one half to 4 inches. The number of pieces smaller than one centimeter orbiting Earth is in the millions.
Space station crew members have a colorful history of shoving items into orbit. Perhaps their biggest hit was SuitSat 1 in 2006, an old Russian spacesuit stuffed with trash from the station and equipped with a battery-powered transmitter.
A cosmonaut tossed it overboard during a spacewalk and watched it tumble slowly away, looking ominously like a lost colleague. It sent weak radio signals that enthusiasts tracked from the ground and it orbited for several months. SuitSat was so popular the Russian Space Agency is considering doing it again.
Sources: Wikipedia and ABC News
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