If a dedicated-Shuttle Spacelab flight, a dedicated-pallet flight, or dedicated-FMDM/MPESS flight is prematurely terminated, NASA shall refund the optional services charges for planned, but unused, extra days on orbit. If a complete-pallet or shared-element flight is prematurely terminated, NASA shall refund a pro rata share of the charges for planned, but unused, extra days on orbit to customers whose payload operations are, in NASA's judgment, adversely affected by such premature termination. The basis for proration shall be the customers' Shuttle load factor.