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1 SPACE OPERATIONS AND THE SPACE ENVIRONMENT
Pages 17-30

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From page 17...
... support a wide variety of important missions, including communications, navigation, meteorology, geodesy and geophysics, remote sensing, search and rescue, materials and life sciences, astrophysics, and national security. A broad spectrum of simple and sophisticated functional spacecraft, with masses ranging from tens of kilograms to tens of metric tons and operational lives ranging from one week to more than ten years are employed to carry out these space activities.
From page 18...
... (Additional i~ormabon ~out ~ese and o~er o~it~ reg~ns is conta~ed ir ~e Clossary~ A fe~ spacecraft each year are launched out of Ear~ orbit and into interplanetary space; ~e hazard to ~~re space operations hom ~ese probes is utterly neglig~le. The d~tr~ution of spacecraR around the Ear~ at ~e start of 1994 ~ displayed in Figure 1-1.
From page 19...
... (In this report, we will refer to pre-1992 space activities of the former USSR as "Soviet" and those of 1992 and later as either "Russian" or of the CIS, as appropriate.) In LEO, notable peaks exist around 1,400 to 1,500 km (due in part to a constellation of Russian communication spacecraft and debris from three breakups of Delta rocket bodies)
From page 20...
... Unlike meteoroids, which pass through and leave the near-Earth area, artificial space debris orbit the Earth and may remain in orbit for long periods of time. Of the 23,000 space objects officially cataloged by the U.S.
From page 21...
... Each other type of object in Earth orbit may be classified as belonging to one of four types of debris: nonfunctional spacecraft, rocket bodies, mission-related debris, and fragmentation debris. Figure 1-3 indicates the relative numbers of cataloged functional spacecraft and debris as of March 1994.
From page 22...
... ROCKET BODIES (17%) FIGURE 1-3 Cataloged space objects by category, 1994.
From page 23...
... The presence of rocket bodies in orbit is of particular importance to the future evolution of the Earth's debris population due to their characteristically large dimensions and to the potentially explosive residual propellants and other energy sources they may contain. Although the largest stages, which are generally used to deliver spacecraft and any additional stages into LEO, usually reenter the atmosphere rapidly, smaller stages used to transfer spacecraft into higher orbits and insert TWO FAIRINGS SUBORBITAL _, (LIFETIME '20 MIN.)
From page 24...
... While the orbital lifetimes of individual particles are relatively short, a considerable average population is suggested by examinations of impacts on exposed spacecraft surfaces. More than 25 solid rocket motor firings were conducted in orbit during 1993.
From page 25...
... Fragmentation Debris Fragmentation debris the single largest element of the cataloged Earth-orbiting space object population consists of space objects created during breakups and the products of deterioration. Breakups are typically destructive events that generate numerous smaller objects with a wide range of initial velocities.
From page 26...
... SOURCE: Kaman Sciences Corporation. ORBITAL DEBRIS An, Phase 1 Phase 2 .~ Phase 3 Another serious degradation problem involves the flaking of small paint chips as a space object ages under the influence of solar radiation, atomic oxygen, and other forces.
From page 27...
... Small debris can also be affected by solar radiation pressure, plasma drag, and electrodynamic forces, although the effects of plasma drag and electrodynamic forces are typically dwarfed by the effects of solar radiation pressure. The rate at which a space object loses altitude is a function of its mass, its average cross-sectional area impinging on the atmosphere, and the atmospheric density.
From page 28...
... Insulation materials and inflatable space objects are often strongly affected by solar radiation pressure. Debris from the ruptured Pageos balloon, for example, exhibited strong orbital perturbations due to solar radiation pressure, as has some debris from more conventional fragmentations.
From page 29...
... SOURCE: National Aeronautics and Space Administration. composed primarily of large objects that were launched into low orbits (most of the mass is in the form of large multiton rocket bodies)
From page 30...
... 1993. Risk analysis of 1-2 cm debris population for solid rocket motors and mitigation possibilities for geotransfer orbits.


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