Debris

Debris (UK: /ˈdɛbriː, ˈdeɪbriː/, US: /dəˈbriː/) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, discarded, or as in geology, large rock fragments left by a melting glacier etc. Depending on context, debris can refer to a number of different things. The first apparent use of the French word in English is in a 1701 description of the army of Prince Rupert upon its retreat from a battle with the army of Oliver Cromwell, in England.[1]

Disaster

In disaster scenarios, tornadoes leave behind large pieces of houses and mass destruction overall. This debris also flies around the tornado itself when it is in progress. The tornado's winds capture debris it kicks up in its wind orbit, and spins it inside its vortex. The tornado's wind radius is larger than the funnel itself. tsunamis and hurricanes also bring large amounts of debris, such as Hurricane Katrina in 2005 and Hurricane Sandy in 2012. Earthquakes rock cities to rubble debris.

Geological

ObsidianDomeCA
Obsidian debris (talus), Obsidian Dome, California.

In geology, debris usually applies to the remains of geological activity including landslides, volcanic explosions, avalanches, mudflows or Glacial lake outburst floods (Jökulhlaups) and moraine, lahars, and lava eruptions. Geological debris sometimes moves in a stream called a debris flow. When it accumulates at the base of hillsides, it can be called "talus" or "scree".

In mining, debris called attle usually consists of rock fragments which contain little or no ore.

Marine

Marine debris on Hawaiian coast
Marine debris washed ashore on Hawaii

Marine debris applies to floating garbage such as bottles, cans, styrofoam, cruise ship waste, offshore oil and gas exploration and production facilities pollution, and fishing paraphernalia from professional and recreational boaters. Marine debris is also called litter or flotsam and jetsam. Objects that can constitute marine debris include used automobile tires, detergent bottles, medical wastes, discarded fishing line and nets, soda cans, and bilge waste solids.

In addition to being unsightly, it can pose a serious threat to marine life, boats, swimmers, divers, and others. For example, each year millions of seabirds, sea turtles, fish, and marine mammals become entangled in marine debris, or ingest plastics which they have mistaken for food. As many as 30,000 northern fur seals per year get caught in abandoned fishing nets and either drown or suffocate. Whales mistake plastic bags for squid, and birds may mistake plastic pellets for fish eggs. At other times, animals accidentally eat the plastic while feeding on natural food.

The largest concentration of marine debris is the Great Pacific Garbage Patch.

Marine debris most commonly originates from land-based sources. Various international agencies are currently working to reduce marine debris levels around the world.

Meteorological

In meteorology, debris usually applies to the remains of human habitation and natural flora after storm related destruction. This debris is also commonly referred to as storm debris. Storm debris commonly consists of roofing material, downed tree limbs, downed signs, downed power lines and poles, and wind-blown garbage. Storm debris can become a serious problem immediately after a storm, in that it often blocks access to individuals and communities that may require emergency services. This material frequently exists in such large quantities that disposing of it becomes a serious issue for a community. In addition, storm debris is often hazardous by its very nature, since, for example, downed power lines annually account for storm-related deaths.

Space

Space debris usually refers to the remains of spacecraft that have either fallen to Earth or are still orbiting Earth. Space debris may also consist of natural components such as chunks of rock and ice. The problem of space debris has grown as various space programs have left legacies of launches, explosions, repairs, and discards in both low Earth orbit and more remote orbits. These orbiting fragments have reached a great enough proportion to constitute a hazard to future space launches of both satellite and manned vehicles. Various government agencies and international organizations are beginning to track space debris and also research possible solutions to the problem. While many of these items, ranging in size from nuts and bolts to entire satellites and spacecraft, may fall to Earth, other items located in more remote orbits may stay aloft for centuries. The velocity of some of these pieces of space junk have been clocked in excess of 17,000 miles per hour (27,000 km/h). A piece of space debris falling to Earth leaves a fiery trail, just like a meteor.

A debris disk is a circumstellar disk of dust and debris in orbit around a star.

Surgical

In medicine, debris usually refers to biological matter that has accumulated or lodged in surgical instruments and is referred to as surgical debris. The presence of surgical debris can result in cross-infections or nosocomial infections if not removed and the affected surgical instruments or equipment properly disinfected.

War

Boys Toys edit
A child plays on an abandoned tank outside Phnom Penh, Cambodia in 1991

In the aftermath of a war, large areas of the region of conflict are often strewn with war debris in the form of abandoned or destroyed hardware and vehicles, mines, unexploded ordnance, bullet casings and other fragments of metal.

Much war debris has the potential to be lethal and continues to kill and maim civilian populations for years after the end of a conflict. The risks from war debris may be sufficiently high to prevent or delay the return of refugees. In addition war debris may contain hazardous chemicals or radioactive components that can contaminate the land or poison civilians who come into contact with it. Many Mine clearance agencies are also involved in the clearance of war debris.

Land mines in particular are very dangerous as they can remain active for decades after a conflict, which is why they have been banned by international war regulations.

In November 2006 the Protocol on Explosive Remnants of War[2] came into effect with 92 countries subscribing to the treaty that requires the parties involved in a conflict to assist with the removal of unexploded ordnance following the end of hostilities.[3]

Some of the countries most affected by war debris are Afghanistan, Angola, Cambodia, Iraq and Laos.

Similarly military debris may be found in and around firing range and military training areas.

Debris can also be used as cover for military purposes, depending on the situation.

Culinary

In South Louisiana's Creole and Cajun cultures, debris (pronounced "DAY-bree") refers to chopped organs such as liver, heart, kidneys, tripe, spleen, brain, lungs and pancreas.

See also

  • Woody debris

References

  1. ^ Warwick, Sir Philip. (1701). Memoires of the Reigne of King Charles I: With a continuation to the happy restoration of King Charles II. London: Ri.Chiswell. p. 208.
  2. ^ "Protocol on Explosive Remnants of War (Protocol V to the 1980 Convention)". International Committee of the Red Cross. 2003. Retrieved 2006-06-20.
  3. ^ "War Debris Treaty To Come Into Force in November". Defense News. 2006. Retrieved 2006-06-20.

External links

Ablation

Ablation is removal or destruction of material from an object by vaporization, chipping, or other erosive processes. Examples of ablative materials are described below, and include spacecraft material for ascent and atmospheric reentry, ice and snow in glaciology, biological tissues in medicine and passive fire protection materials.

Brain terrain

Brain terrain, also called knobs-brain coral and brain coral terrain, is a feature of the Martian surface, consisting of complex ridges found on lobate debris aprons, lineated valley fill and concentric crater fill. It is so named because it suggests the ridges on the surface of the human brain. Wide ridges are called closed-cell brain terrain, and the less common narrow ridges are called open-cell brain terrain. It is thought that the wide closed-cell terrain contains a core of ice, and when the ice disappears the center of the wide ridge collapses to produce the narrow ridges of the open-cell brain terrain. Shadow measurements from HiRISE indicate the ridges are 4-5 meters high. Brain terrain has been observed to form from what has been called an "Upper Plains Unit." The process begins with the formation of stress cracks. The upper plains unit fell from the sky as snow and as ice coated dust.Today it is widely accepted that glacier-like forms, lobate debris aprons, lineated valley fill, and concentric fill are all related in that they have the same surface texture. Glacier-like forms in valleys and cirque-like alcoves may coalesce with others to produce lobate debris aprons. When opposing lobate debris aprons converge, linear valley fill results. They probably all contain ice-rich material.

Many of these features are found in the Northern hemisphere in parts of a boundary called the Martian dichotomy, mostly between 0 and 70 E longitudes. Near this area are regions that are named from ancient places: Deuteronilus Mensae, Protonilus Mensae, and Nilosyrtis Mensae.

Lobate debris aprons, lineated valley fill, and concentric fill probably have dirt and rock debris covering huge deposits of ice.

Debris disk

A debris disk (American English), or debris disc (Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris disks have been found around both mature and young stars, as well as at least one debris disk in orbit around an evolved neutron star. Younger debris disks can constitute a phase in the formation of a planetary system following the protoplanetary disk phase, when terrestrial planets may finish growing. They can also be produced and maintained as the remnants of collisions between planetesimals, otherwise known as asteroids and comets.By 2001, over 900 candidate stars had been found to possess a debris disk. They are usually discovered by examining the star system in infrared light and looking for an excess of radiation beyond that emitted by the star. This excess is inferred to be radiation from the star that has been absorbed by the dust in the disk, then re-radiated away as infrared energy.Debris disks are often described as massive analogs to the debris in the Solar System. Most known debris disks have radii of 10–100 astronomical units (AU); they resemble the Kuiper belt in the Solar System, but with much more dust. Some debris disks contain a component of warmer dust located within 10 AU from the central star. This dust is sometimes called exozodiacal dust by analogy to zodiacal dust in the Solar System.

Debris flow

Debris flows are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors. They generally have bulk densities comparable to those of rock avalanches and other types of landslides (roughly 2000 kilograms per cubic meter), but owing to widespread sediment liquefaction caused by high pore-fluid pressures, they can flow almost as fluidly as water. Debris flows descending steep channels commonly attain speeds that surpass 10 m/s (36 km/h), although some large flows can reach speeds that are much greater. Debris flows with volumes ranging up to about 100,000 cubic meters occur frequently in mountainous regions worldwide. The largest prehistoric flows have had volumes exceeding 1 billion cubic meters (i.e., 1 cubic kilometer). As a result of their high sediment concentrations and mobility, debris flows can be very destructive.

Notable debris-flow disasters of the twentieth century involved more than 20,000 fatalities in Armero, Colombia in 1985 and tens of thousands in Vargas State, Venezuela in 1999.

Feces

Feces (or faeces) are the solid or semisolid remains of food that could not be digested in the small intestine. Bacteria in the large intestine further break down the material. Feces contain a relatively small amount of metabolic waste products such as bacterially altered bilirubin, and the dead epithelial cells from the lining of the gut.Feces are discharged through the anus or cloaca during defecation.

Feces can be used as fertilizer or soil conditioner in agriculture. It can also be burned as fuel or dried and used for construction. Some medicinal uses have been found. In the case of human feces, fecal transplants or fecal bacteriotherapy are in use. Urine and feces together are called excreta.

Great Pacific garbage patch

The Great Pacific garbage patch, also described as the Pacific trash vortex, is a gyre of marine debris particles in the north central Pacific Ocean. It is located roughly from 135°W to 155°W and 35°N to 42°N. The collection of plastic and floating trash originates from the Pacific Rim, including countries in Asia, North America, and South America. The patch is actually "two enormous masses of ever-growing garbage". What has been referred to as the "Eastern Garbage Patch" lies between Hawaii and California, while the "Western Garbage Patch" extends eastward from Japan to the Hawaiian Islands. An ocean current about 6,000 miles long, referred to as the Subtropical Convergence Zone, connects the two patches, which extend over an indeterminate area of widely varying range, depending on the degree of plastic concentration used to define the affected area. The vortex is characterized by exceptionally high relative pelagic concentrations of plastic, chemical sludge, wood pulp, and other debris trapped by the currents of the North Pacific Gyre.Despite the common public perception of the patch existing as giant islands of floating rubbish, its low density (4 particles per cubic meter) prevents detection by satellite imagery, or even by casual boaters or divers in the area. This is because the patch is a widely dispersed area consisting primarily of suspended "fingernail-sized or smaller bits of plastic", often microscopic, particles in the upper water column. Researchers from The Ocean Cleanup project claimed that the patch covers 1.6 million square kilometers. The plastic concentration is estimated to be up to 100 kilograms per square kilometer in the center, going down to 10 kilograms per square kilometer in the outer parts of the patch. An estimated 80,000 metric tons of plastic inhabit the patch, totaling 1.8 trillion pieces. 92% of the mass in the patch comes from objects larger than 0.5 centimeters, while 94% of the total objects are represented by microplastics.Some of the plastic in the patch has been found to be over 50 years old, and includes fragments of and items such as "plastic lighters, toothbrushes, water bottles, pens, baby bottles, cell phones, plastic bags, and nurdles". It is estimated that approximately "100 million tons of plastic are generated [globally] each year", and about 10% of that plastic ends up in the oceans. The United Nations Environmental Program recently estimated that "for every square mile of ocean", there are about "46,000 pieces of plastic". The small fibers of wood pulp found throughout the patch are "believed to originate from the thousands of tons of toilet paper flushed into the oceans daily". The patch is believed to have increased "10-fold each decade" since 1945.Research indicates that the patch is rapidly accumulating. A similar patch of floating plastic debris is found in the Atlantic Ocean, called the North Atlantic garbage patch.

Lahar

A lahar ( , from Javanese: ꦮ꧀ꦭꦲꦂ, romanized: wlahar) is a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water. The material flows down from a volcano, typically along a river valley.Lahars are extremely destructive: they can flow tens of metres per second (22 mph or more), they have been known to be up to 140 metres (460 ft) deep, and large flows tend to destroy any structures in their path. Notable lahars include those at Mount Pinatubo and Nevado del Ruiz, the latter of which covered entire towns and killed thousands of people.

Landslide

The term landslide or less frequently, landslip, refers to several forms of mass wasting that include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable.

Lineated valley fill

Lineated valley fill (LVF), also called lineated floor deposit, is a feature of the floors of some channels on Mars, exhibiting ridges and grooves that seem to flow around obstacles. Shadow measurements show that at least some of the ridges are several metres high. LVF is believed to be ice-rich. Hundreds of metres of ice probably lie protected in LVF under a thin layer of debris. The debris consists of wind-borne dust, material from alcove walls, and lag material remaining after ice sublimated (changed from a solid directly to a gas) from a rock-ice mixture. Some glaciers on Earth show similar ridges. High-resolution pictures taken with HiRISE reveal that some of the surfaces of lineated valley fill are covered with strange patterns called closed-cell and open-cell brain terrain. The terrain resembles a human brain. It is believed to be caused by cracks in the surface accumulating dust and other debris, together with ice sublimating from some of the surfaces. The cracks are the result stress from gravity and seasonal heating and cooling. This same type of surface is present on Lobate debris aprons and Concentric crater fill so all three are believed to be related.

Lineated floor deposits began as lobate debris aprons (LDAs), which form as material leaves narrow mountain valleys and spreads out as an apron. By tracing the paths of the ridges on LDAs, researchers have come to believe that the curved ridges characteristic of lobate debris aprons straighten out to form the more or less straight ridges of LVF.In the regions where LVF and LDAs occur, many craters have concentric crater fill: large ridges and other surfaces nicknamed brain terrain, after the surface corrugations of the human brain.The study of lineated valley fill and other features related to debris-covered ice has been greatly aided by the abundance of data received from Mars orbiting instruments. Excellent images have been obtained from THEMIS, MOC, CTX, and HiRISE. Detailed altimetry was collected by MOLA.

The Mars Reconnaissance Orbiter's Shallow Radar gave a strong reflection from the top and base of LDAs, meaning that pure water ice made up the bulk of the formation (between the two reflections), strong evidence that the LDAs in Hellas Planitia are glaciers covered with a thin layer of rocks. Since lineated valley terrain is derived from lobate debris aprons, it probably contains buried ice—at least in places.

Lobate debris apron

Lobate debris aprons (LDAs) are geological features on Mars, first seen by the Viking Orbiters, consisting of piles of rock debris below cliffs. These features have a convex topography and a gentle slope from cliffs or escarpments, which suggest flow away from the steep source cliff. In addition, lobate debris aprons can show surface lineations as do rock glaciers on the Earth.

The Mars Reconnaissance Orbiter's Shallow Radar gave a strong reflection from the top and base of LDAs, meaning that pure water ice made up the bulk of the formation (between the two reflections). This is evidence that the LDAs in Hellas Planitia are glaciers covered with a thin layer of rocks. In addition, radar studies in Deuteronilus Mensae show that all lobate debris aprons examined in that region contain ice.The experiments of the Phoenix lander and the studies of the Mars Odyssey from orbit show that frozen water exists just under the surface of Mars in the far north and south (high latitudes). Most of the ice was deposited as snow when the climate was different. The discovery of water ice in LDAs demonstrates that water is found at even lower latitudes. Future colonists on Mars will be able to tap into these ice deposits, instead of having to travel to much higher latitudes. Another major advantage of LDAs over other sources of Martian water is that they can easily be detected and mapped from orbit. Lobate debris aprons are shown below from the Phlegra Montes which are at a latitude of 38.2 degrees north. The Phoenix lander set down at about 68 degrees north latitude, so the discovery of water ice in LDAs greatly expands the range of water easily available on Mars. It is far easier to land a spaceship near the equator of Mars, so the closer water is available to the equator the better it will be for colonists.

Low Earth orbit

A low Earth orbit (LEO) is an Earth-centered orbit with an altitude of 2,000 km (1,200 mi) or less (approximately one-third of the radius of Earth), or with at least 11.25 periods per day (an orbital period of 128 minutes or less) and an eccentricity less than 0.25. Most of the manmade objects in outer space are in LEO.There is a large variety of other sources that define LEO in terms of altitude. The altitude of an object in an elliptic orbit can vary significantly along the orbit. Even for circular orbits, the altitude above ground can vary by as much as 30 km (19 mi) (especially for polar orbits) due to the oblateness of Earth's spheroid figure and local topography. While definitions based on altitude are inherently ambiguous, most of them fall within the range specified by an orbit period of 128 minutes because, according to Kepler's third law, this corresponds to a semi-major axis of 8,413 km (5,228 mi). For circular orbits, this in turn corresponds to an altitude of 2,042 km (1,269 mi) above the mean radius of Earth, which is consistent with some of the upper altitude limits in some LEO definitions.

The LEO region is defined by some sources as the region in space that LEO orbits occupy. Some highly elliptical orbits may pass through the LEO region near their lowest altitude (or perigee) but are not in an LEO Orbit because their highest altitude (or apogee) exceeds 2,000 km (1,200 mi). Sub-orbital objects can also reach the LEO region but are not in an LEO orbit because they re-enter the atmosphere. The distinction between LEO orbits and the LEO region is especially important for analysis of possible collisions between objects which may not themselves be in LEO but could collide with satellites or debris in LEO orbits.

The International Space Station conducts operations in LEO. All crewed space stations to date, as well as the majority of satellites, have been in LEO. The altitude record for human spaceflights in LEO was Gemini 11 with an apogee of 1,374.1 km (853.8 mi). Apollo 8 was the first mission to carry humans beyond LEO on December 21–27, 1968. The Apollo program continued during the four-year period spanning 1968 through 1972 with 24 astronauts who flew lunar flights but since then there have been no human spaceflights beyond LEO.

Malaysia Airlines Flight 370

Malaysia Airlines Flight 370 (also referred to as MH370 or MAS370) was a scheduled international passenger flight operated by Malaysia Airlines that disappeared on 8 March 2014 while flying from Kuala Lumpur International Airport to its destination, Beijing Capital International Airport. The crew of the Boeing 777-200ER aircraft last communicated with air traffic control (ATC) around 38 minutes after takeoff when the flight was over the South China Sea. The aircraft was lost from ATC radar screens minutes later but was tracked by military radar for another hour, deviating westwards from its planned flight path, crossing the Malay Peninsula and Andaman Sea. It left radar range 200 nautical miles (370 km) northwest of Penang Island in northwestern Malaysia. With all 227 passengers and 12 crew aboard presumed dead, the disappearance of Flight 370 was the deadliest incident involving a Boeing 777 and the deadliest in Malaysia Airlines' history until it was surpassed in both regards by Malaysia Airlines Flight 17, which was shot down while flying over eastern Ukraine four months later. The combined loss caused significant financial problems for Malaysia Airlines, which was renationalised by the Malaysian government in December 2014.

The search for the missing airplane, which became the most costly in aviation history, focused initially on the South China and Andaman seas, before analysis of the aircraft's automated communications with an Inmarsat satellite identified a possible crash site somewhere in the southern Indian Ocean. The lack of official information in the days immediately after the disappearance prompted fierce criticism from the Chinese public, particularly from relatives of the passengers; most people on board Flight 370 were of Chinese origin. Several pieces of marine debris confirmed to be from the aircraft washed ashore in the western Indian Ocean during 2015 and 2016. After a three-year search across 120,000 square kilometres (46,000 sq mi) of ocean failed to locate the aircraft, the Joint Agency Coordination Centre heading the operation suspended their activities in January 2017. A second search launched in January 2018 by the private contractor Ocean Infinity also ended without success after six months.

The disappearance of Flight 370 has been dubbed one of the greatest aviation mysteries of all time. Relying mostly on analysis of data from the Inmarsat satellite with which the aircraft last communicated, the Australian Transport Safety Bureau proposed initially that a hypoxia event was the most likely cause given the available evidence, although there has not been any consensus concerning this theory among investigators. At various stages of the investigation, possible hijacking scenarios were considered, including crew involvement, and suspicion of the airplane's cargo manifest; many unofficial theories have also been proposed by the media. The Malaysian Ministry of Transport's final report from July 2018 was inconclusive but highlighted Malaysian air traffic controllers' failures to attempt to communicate with the aircraft shortly after its disappearance. In the absence of a definitive cause of disappearance, those air transport industry safety recommendations and regulations citing Flight 370 have been intended mostly to prevent a repetition of the circumstances associated with the loss. These include increased battery life on underwater locator beacons, lengthening of recording times on flight data recorders and cockpit voice recorders, and new standards for aircraft position reporting over the open ocean.

Marine debris

Marine debris, also known as marine litter, is human-created waste that has deliberately or accidentally been released in a sea or ocean. Floating oceanic debris tends to accumulate at the center of gyres and on coastlines, frequently washing aground, when it is known as beach litter or tidewrack. Deliberate disposal of wastes at sea is called ocean dumping. Naturally occurring debris, such as driftwood, are also present.

With the increasing use of plastic, human influence has become an issue as many types of (petrochemical) plastics do not biodegrade. Waterborne plastic poses a serious threat to fish, seabirds, marine reptiles, and marine mammals, as well as to boats and coasts. Dumping, container spillages, litter washed into storm drains and waterways and wind-blown landfill waste all contribute to this problem.

In efforts to prevent and mediate marine debris and pollutants, laws and policies have been adopted internationally. Depending on relevance to the issues and various levels of contribution, some countries have introduced more specified protection policies.

Meteoroid

A meteoroid () is a small rocky or metallic body in outer space.

Meteoroids are significantly smaller than asteroids, and range in size from small grains to one-meter-wide objects. Objects smaller than this are classified as micrometeoroids or space dust. Most are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars.When a meteoroid, comet, or asteroid enters Earth's atmosphere at a speed typically in excess of 20 km/s (72,000 km/h; 45,000 mph), aerodynamic heating of that object produces a streak of light, both from the glowing object and the trail of glowing particles that it leaves in its wake. This phenomenon is called a meteor or "shooting star". A series of many meteors appearing seconds or minutes apart and appearing to originate from the same fixed point in the sky is called a meteor shower. If that object withstands ablation from its passage through the atmosphere as a meteor and impacts with the ground, it is then called a meteorite.

An estimated 25 million meteoroids, micrometeoroids and other space debris enter Earth's atmosphere each day, which results in an estimated 15,000 tonnes of that material entering the atmosphere each year.

Moraine

A moraine is any glacially formed accumulation of unconsolidated glacial debris (regolith and rock) that occurs in both currently and formerly glaciated regions on Earth (i.e. a past glacial maximum), through geomorphological processes. Moraines are formed from debris previously carried along by a glacier, and normally consist of somewhat rounded particles ranging in size from large boulders to minute glacial flour. Lateral moraines are formed at the side of the ice flow and terminal moraines at the foot, marking the maximum advance of the glacier. Other types of moraine include ground moraines (till-covered areas with irregular topography) and medial moraines (moraines formed where two glaciers meet).

Plastic pollution

Plastic pollution is the accumulation of plastic objects and particles (e.g.: plastic bottles and much more) in the Earth's environment that adversely affects wildlife, wildlife habitat, and humans. Plastics that act as pollutants are categorized into micro-, meso-, or macro debris, based on size. Plastics are inexpensive and durable, and as a result levels of plastic production by humans are high. However, the chemical structure of most plastics renders them resistant to many natural processes of degradation and as a result they are slow to degrade. Together, these two factors have led to a high prominence of plastic pollution in the environment.

Plastic pollution can afflict land, waterways and oceans. It is estimated that 1.1 to 8.8 million metric tons (MT) of plastic waste enters the ocean from coastal communities each year. Living organisms, particularly marine animals, can be harmed either by mechanical effects, such as entanglement in plastic objects, problems related to ingestion of plastic waste, or through exposure to chemicals within plastics that interfere with their physiology. Effects on humans include disruption of various hormonal mechanisms.

As of 2018, about 380 million tons of plastic is produced worldwide each year. From the 1950s up to 2018, an estimated 6.3 billion tons of plastic has been produced worldwide, of which an estimated 9% has been recycled and another 12% has been incinerated. This large amount of plastic waste enters the environment, with studies suggesting that the bodies of 90% of seabirds contain plastic debris. In some areas there have been significant efforts to reduce the prominence of free range plastic pollution, through reducing plastic consumption, litter cleanup, and promoting plastic recycling.Some researchers suggest that by 2050 there could be more plastic than fish in the oceans by weight.

Satellite Catalog Number

The Satellite Catalog Number (also known as NORAD Catalog Number, NORAD ID, NASA catalog number, USSPACECOM object number or simply catalog number and similar variants) is a sequential five-digit number assigned by USSTRATCOM (United States Strategic Command) in order of discovery to all man-made objects in Earth orbit (including rocket bodies and debris) and space probes launched from Earth. The first catalogued object, catalog number 00001, is the Sputnik 1 launch vehicle, with the Sputnik 1 satellite assigned catalog number 00002.Objects that fail to orbit or orbit for a short time are not catalogued. The minimum object size in the catalog is 10 centimeters in diameter. As of June 23, 2019, the catalog listed 44,336 objects including 8,558 satellites launched into orbit since 1957. 17,480 of them were actively tracked while 1,335 were lost. ESA estimates there are about 34,000 orbiting debris of the size USSTRATCOM is capable to track as of January 2019USSTRATCOM shares the catalog via space-track.org website. 18th Space Control Squadron (18 SPCS) is the unit that maintains the catalog.

Space Shuttle Columbia disaster

On February 1, 2003, the Space Shuttle Columbia disintegrated during atmospheric entry, killing all seven crew members. The disaster was the second fatal accident in the Space Shuttle program, after Challenger, which broke apart 73 seconds after liftoff and killed the seven-member crew in 1986.

During the launch of STS-107, Columbia's 28th mission, a piece of foam insulation broke off from the Space Shuttle external tank and struck the left wing of the orbiter. A few previous shuttle launches had seen damage ranging from minor to nearly catastrophic from foam shedding, but some engineers suspected that the damage to Columbia was more serious. NASA managers limited the investigation, reasoning that the crew could not have fixed the problem if it had been confirmed. When Columbia re-entered the atmosphere of Earth, the damage allowed hot atmospheric gases to penetrate the heat shield and destroy the internal wing structure, which caused the spacecraft to become unstable and break apart.After the disaster, Space Shuttle flight operations were suspended for more than two years, as they had been after the Challenger disaster. Construction of the International Space Station (ISS) was put on hold; the station relied entirely on the Russian Roscosmos State Space Corporation for resupply for 29 months until Shuttle flights resumed with STS-114 and 41 months for crew rotation until STS-121.

Several technical and organizational changes were made, including adding a thorough on-orbit inspection to determine how well the shuttle's thermal protection system had endured the ascent, and keeping a designated rescue mission ready in case irreparable damage was found. Except for one final mission to repair the Hubble Space Telescope, subsequent shuttle missions were flown only to the ISS so that the crew could use it as a haven in case damage to the orbiter prevented safe reentry.

Space debris

Initially, the term space debris referred to the natural debris found in the Solar System: asteroids, comets, and meteoroids. However, with the 1979 beginning of the NASA Orbital Debris Program, the term also refers to the debris (alt. space waste or space garbage) from the mass of defunct, artificially created objects in space, especially Earth orbit. These include old satellites and spent rocket stages, as well as the fragments from their disintegration and collisions.

As of December 2016, five satellite collisions have generated space debris. Space debris is also known as orbital debris, space junk, space waste, space trash, space litter, or space garbage.As of 5 July 2016, the United States Strategic Command tracked a total of 17,852 artificial objects in orbit above the Earth, including 1,419 operational satellites. However, these are just objects large enough to be tracked. As of January 2019, more than 128 million bits of debris smaller than 1 cm (0.4 in), about 900,000 pieces of debris 1–10 cm, and around 34,000 of pieces larger than 10 cm were estimated to be in orbit around the Earth. Collisions with debris have become a hazard to spacecraft; they cause damage akin to sandblasting, especially to solar panels and optics like telescopes or star trackers that cannot be covered with a ballistic Whipple shield (unless it is transparent).Below 2,000 km (1,200 mi) Earth-altitude, pieces of debris are denser than meteoroids; most are dust from solid rocket motors, surface erosion debris like paint flakes, and frozen coolant from RORSAT (nuclear-powered satellites).

For comparison, the International Space Station orbits in the 300–400 kilometres (190–250 mi) range, and the 2009 satellite collision and 2007 antisat test occurred at 800 to 900 kilometres (500 to 560 mi) altitude. The ISS has Whipple shielding; however, known debris with a collision chance over 1/10,000 are avoided by maneuvering the station.

The Kessler syndrome, a runaway chain reaction of collisions exponentially increasing the amount of debris, has been hypothesized to ensue beyond a critical density. This could affect useful polar-orbiting bands, increases the cost of protection for spacecraft missions and could destroy live satellites. Whether Kessler syndrome is already underway has been debated. The measurement, mitigation, and potential removal of debris are conducted by some participants in the space industry.

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