WORLDWIDE DIFFERENTIAL GPS FOR SPACE SHUTTLE LANDING OPERATIONS

THERE IS A PROPOSAL TO PUT GPS ABOARD THE SPACE SHUTTLE FOR PURPOSES OF PROVIDING AUTONOMOUS NAVIGATION. ONE OF THE BENEFITS OF AUTONOMOUS NAVIGATION WILL BE THE ABILITY TO LAND THE SHUTTLE IN AN EMERGENCY AT ANY SUITABLE AIRSTRIP. IF AN EMERGENCY LANDING IS REQUIRED, THERE WILL BE NO ASSURANCE THAT THE CHOSEN AIRSTRIP WILL HAVE GOOD VISIBILITY. IF THE GPS ON THE SHUTTLE IS OPERATED IN A STANDALONE MODE, THERE IS NO PROTECTION AGAINST A MALFUNCTIONING GPS SATELLITE CAUSING AN INCORRECT NAVIGATION SOLUTION. THE PROPOSED INNOVATION ADDRESSES THE TWO CONCERNS NOTED ABOVE. IT WILL PROVIDE DIFFERENTIAL GPS TO THE SHUTTLE ON A REAL-TIME, GLOBAL BASIS. THIS WILL IMPROVE THE SHUTTLES NAVIGATION ACCURACY AND CONSEQUENTLY MINIMIZE THE LANDING RISK DURING PERIODS OF LOW VISIBILITY. THE PROPOSED INNOVATION WILL ADDITIONALLY PROVIDE INTEGRITY MONITORING AND MANAGEMENT OF THE GPS SYSTEMS CONCURRENT WITH PROVIDING DIFFERENTIAL GPS CORRECTION TERMS. THIS WILL PREVENT THE SHUTTLE RECEIVER FROM USING GPS SATELLITES WHICH ARE MALFUNCTIONING BUT HAVE NOT BEEN IDENTIFIED AS BEING SO BY THE CONTROL SEGMENT.