Finding. NASA plans to modify the orbiter radiators and wing insulation to reduce the risk of early mission termination and critical failure. These modifications appear to be positive steps that will have a minimal negative effect on the program.

In Chapter 3, the committee suggested that NASA should continue to assess the potential of various hardware modifications to improve the survivability of the orbiter in the face of the meteoroid and orbital debris hazard. This assessment could also be used to determine future hardware modifications. Although deciding which areas should be assessed in detail will require further analysis, NASA may wish to consider the following areas:

  • wing locations that contain multiple hydraulic and electrical lines vital for elevon motion and flight control

  • additional modifications inside the leading edges of wings and wing areas

  • payload bay pressurized modules, such as the Spacehab and Spacelab modules

  • pressure vessels in the payload bay, including those on the extended duration module

  • a replacement for the current payload bay liner and multilayer insulation that would provide better protection of the multiple components and pressure vessels in the orbiter mid-body

  • design options to replace existing insulation blankets with materials that provide better protection from meteoroids and orbital debris

  • reinforcement materials on the aft bulkhead of the cabin to provide more robust protection from meteoroids and orbital debris

  • relocation of redundant systems that may be vulnerable to the impact of meteoroids and debris

RECOMMENDATIONS

Recommendation 8. NASA should assess the effect of plans for the ISS era that will render the shuttle unable to use some current operational techniques to protect the vehicle from meteoroids and orbital debris.

Recommendation 9. NASA should reconsider conducting on-orbit surveys of the orbiter exterior to detect impact damage and repair it if necessary.

Recommendation 10. NASA should investigate additional modifications to the orbiter to improve its survivability.

REFERENCES

Combs, N.E. 1997. Personal communication to J.P.Loftus, Assistant Director (Plans), NASA Johnson Space Center. July 7, 1997.



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