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work overtime where possible.  Due to the nature of the special skills required on a per cargo and per vehicle basis, the KSC estimates are that the turnaround will always disrupt KSC flow even if a permanent turnaround operation is set up at EAFB/Dryden Flight Research Center (DFRC).

Though the risk is probably small, the ferry turnaround operation does impose an extra handling risk to the Orbiter, not only in the tow/mate/demate operation but also in the ferry operation.  Very minimal precipitation can cause significant damage to the Orbiter thermal protection system (TPS). This already has occurred.  Further, there is an increased heavy weight takeoff and landing risk associated with the operation.  In addition, the ferry/ turnaround operation is a single string operation.  There is only one SCA and one tail cone, and in many cases unique GSE equipment exist.  An outage of the SCA could halt the entire Space Shuttle Program for up to 18 months.

In summary, the original goals are still valid.  Safe, routine KSC landings will result in lower costs, shorter turnaround time, less workforce disruption, lower Orbiter exposure to handling damage, and more effective cargo operations.  The program is not anxious to operate unsafely but, rather, is anxious to operate safely and efficiently.

V. CREW CONCERNS

The crew concerns with KSC landings are stated below.  These concerns focus on the weather at KSC, the Orbiter landing and deceleration systems (brakes, tires, and nosewheel steering), the KSC runway and its environment, and pressures due to schedule and training.  The procedures required to merely make the system operate normally are numerous and complex and are extremely demanding when compared to normal aircraft landing procedures.  Some procedures are not at all intuitive and actually run counter to normal piloting instinctive reaction.  Crew adaptation to zero gravity for normal end of mission landings cannot be simulated in the training environment.  The Shuttle Training Aircraft does not continue to touchdown and the Shuttle Mission Simulator does not adequately simulate required rollout motion cues.  It is believed that one or a combination of these items could cause a Space Shuttle landing accident, therefore making a KSC landing imprudent.

The NSTS Program considers many failures or combinations of failures to be non-credible and, therefore, these cases are not used to drive systems design requirements.  However, in a technically sophisticated and still developing program the uncertainties in our knowledge dictate that we should make every effort to ensure a safe flight.

Specifically, the concerns are as follows for KSC landings.

1. Weather - Difficulty of accurately forecasting occurrence of thunderstorms, fog, and crosswinds.  Stability over 1.5-hour period.

-B5-

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