Orbital Debris A Technical Assessment (1995) / Chapter Skim
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6 DESIGNING FOR THE DEBRIS ENVIRONMENT
6 DESIGNING FOR THE DEBRIS ENVIRONMENT
Pages 119-134
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From page 119... ...
In the past, most spacecraft designers did not consider the debris hazard as a design consideration, due perhaps to a general lack of awareness of the threat, the low level of the perceived hazard, or an unwillingness to undertake the seemingly large research task of quantifying the risk and determining appropriate means to protect their spacecraft. Although large uncertainties still remain, an improved understanding of the debris environment, combined with the growing availability of analytic and experimental tools to quantify the threat to a spacecraft from debris and the development of techniques to protect against debris impacts, now makes it feasible for designers to assess the debris hazard and protect their spacecraft appropriately.
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From page 120... ...
It is important, though, that spacecraft designers who use these tools recognize the assumptions incorporated in them so that they fully understand the uncertainties associated with their output. The overall flux of orbital debris that a spacecraft will experience is largely a function of the spacecraft's size, orbital altitude, inclination, and attitude; the duration of the mission; and the current level of solar activity.
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From page 121... ...
The ESA Reference Model for Space Debris and Meteoroids is also available in an analytic form useful for spacecraft designers (Sdunnus and Klinkrad, 1993~. Once the debris flux and the distribution of impact angles have been estimated, the number of impacts on specific spacecraft components can be predicted.
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From page 122... ...
DAMAGE PROTECTION TECHNIQUES Passive, active, or operational protection schemes can be used to protect spacecraft from debris impact damage. Passive protection generally consists of shielding a spacecraft or its critical components.
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From page 123... ...
The basic advantages of monolithic shields are their simplicity and low volume. Whipple bumper shields, however, will generally provide far better protection against high-velocity orbital debris than the same mass of monolithic shielding.
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From page 124... ...
Whipple bumper shields must protect against not only the high-speed particles that will break apart or vaporize on impact with the bumper but also the slower-moving objects that will simply perforate the bumper and strike the catcher still intact. A spaced shield with a thick monolithic catcher is thus required to protect against the entire range of debris ve Os~ ~ PROJECTILE i_ ~ 1 (a)
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From page 125... ...
, reduce the mass of shielding needed to protect against a given environment and/or reduce the secondary elects produced ny impacts into shields. Various shielding studies for the International Space Station, including a single aluminum Whipple bumper, a double aluminum bumper, and a stuffed Whipple bumper have also been conducted at ESA, NASA, and the National Space Development Agency of Japan (Christiansen, 1994; Ito, 1994; Lambert, 1994~.
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From page 126... ...
As described in Box 6-3, space surveillance organizations use these data to project objects' future locations and to alert spacecraft if they will pass close by, or possibly collide with, another object. For this reason, ground-based collision warning systems, unlike space-based systems, have no problem providing sufficient warning time; they are, however, limited to warning of debris large enough to track from the Earth (currently the minimum size trackable is about 10 cm in diameter, as discussed in Chapter 2)
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From page 127... ...
warning by moving out of Me oncoming objects -~g bow ~ eve m_~er~ c~ib~ ad a gem warnings or by employing other active protection measures. Current collision warning capabilities do not meet these requirements.
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From page 128... ...
Operational Protection Operational protection, including oversizing, redundancy, and mission/architecture design, is currently the most commonly used impact protection method in the spacecraft design community. Most operational protection schemes in place, however, were not implemented to deal with the debris hazard but rather to minimize the chance of mission failure due to component failure from any cause.
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From page 129... ...
Space Shuttle at various orbital attitudes. SOURCE: NASA Johnson Space Center.
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From page 130... ...
~.tiv~ess.~ of.'va.r'~~'Dus'. Shieldir~g ..techniques.-..~ '~he'.~.~st',articles included ~ ' .....
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From page 131... ...
Selective local shielding of critical components can be a costeffective means to reduce spacecraft vulnerability to debris or micrometeoroid impacts. Finding 3: Active protection measures, such as movable shields and shutters, avoidance maneuvering, and direct attacks on incoming impactors,
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From page 132... ...
1989. Orbital Debris Environment for Spacecraft Designed to Operate in Low Earth Orbit.
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From page 133... ...
1993. Laser debris sweeper for the Space Station Freedom.
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