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Protecting the Space Shuttle from Meteoroids and Orbital Debris (1997) / Chapter Skim
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4 Tools for Risk Assessment
Pages 27-35

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From page 27...
... The population of each source component in each representative orbit vanes with altitude according to a formula based on both data and analysis. The data used to develop and validate ORDEM96 were gathered from a wide variety of sources, including the United States Space Command Satellite Catalog, radar sampling of the LEO environment by the Haystack and Goldstone radars, and samples of materials returned from space.
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From page 28...
... The effects of normal, annual meteor showers are incorporated into the model, but rare meteor storms that occur when the Earth passes through a particularly dense portion of a comet dust trail are not. NASA, however, evaluates threats from meteor showers and storms before every shuttle mission and has delayed two missions to avoid potential hazards from meteor showers.
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From page 29...
... This is based on the geometry of the orbiter and its critical subsystems, empirically-derived equations governing damage levels and ballistic limits for various orbiter components and materials, and quantified, impact-based, failure criteria for the orbiter systems and components. Because BUMPER cannot evaluate the damage to orbiter components and systems caused by a given penetration, conservative assessments of a penetration causing critical damage are used unless a detailed study (such as the ones described in Chapter 3)
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From page 30...
... Although this is currently fiscally infeasible, it does indicate what would be required for an accurate representation of the natural variability in population estimates. ORDEM96 averages all of its predictions over at least one year and, therefore, does not account for natural variability in the debris environment although it makes some adjustments for changes in solar activity.
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From page 31...
... Because of limited data and the natural variability in the population of debris smaller than about 5 mm in diameter, ORDEM96 predictions of debris fluxes for individual shuttle missions may be highly inaccurate. Improving ORDEM96 To predict the hazard from debris accurately throughout a shuttle mission, NASA needs either to develop spatially and temporally dependent analytic models for debris smaller than 5 mm in diameter or to greatly increase its ability to gather data about this population.
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From page 32...
... Predicting the short-term hazard to individual shuttle missions from orbital debris more accurately would require a greatly improved capability to sample the population of sub-S mm debris andlor improved models of the sources and orbital behavior of sub-S mm debns. ORDEM96 currently does not include information about debris shape or composition although the amount of damage caused by a collision is strongly affected by the shape and composition of the impactor.
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From page 33...
... The ISCL can generate impact test results at velocities higher than conventional light gas guns, but the projectile in an ISCL test (a hollow cylinder) differs from the solid sphere typically used in light gas gun testing.
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From page 34...
... A sensitivity analysis of BUMPER results to various input parameters could help NASA determine which parts of the model to refine in order to reduce the uncertainties of BUMPER calculations of mission risk most effectively. A rigorous peer review process, including some form of independent validation and verification, could also increase user confidence in the model's results.
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From page 35...
... 1996. Invitation to Participate in the Testing and Verification Phase of the Computer-Based Orbital Debris Environment Model for Spacecraft Design and Observations in Low Earth Orbit.
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Key Terms

  • debris environment
  • space shuttle
  • shuttle mission
  • meteor showers
  • ballistic limit

  • debris wakes
  • light gas
  • hollow cylinder
  • solar activity
  • impact tests

  • damage caused
  • debris risk
  • natural variability
  • meteor storms
  • spherical aluminum

  • individual shuttle
  • finite element
  • spacecraft design
  • external surfaces
  • damage prediction

  • johnson space
  • solid rocket
  • sampling rate
  • gas guns
  • failure criteria

  • nonspherical projectiles
  • radar measurements
  • haystack radar
  • space center
  • orbiter materials


    • This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
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