Space Exploration Technologies (SpaceX) has quickly rebounded from the discovery of cracks in a nozzle on the upper-stage engine of its Falcon 9 booster and is moving ahead with plans to fire off the rocket on Dec. 8 to put the company’s Dragon capsule into orbit on a demonstration run for NASA.
The company had planned to launch its second Falcon 9 rocket on Dec. 7, but inspections of closeout photos on Dec. 6 revealed cracks in the aft end of the launcher’s 9-ft.-long nozzle extensions, which are made of niobium sheet alloy that thins out to about one-third of a millimeter in thickness (Aerospace DAILY, Dec. 7).
“The extension increases the efficiency of the Merlin engine in vacuum and is installed by default on all upper-stage Merlin engines, but that efficiency increase is not required for this mission,” company spokeswoman Kirstin Brost said in a statement.
To fix the problem, engineers cut off the bottom four feet of the nozzle, then ran analysis to assure the engine would perform as expected.
Final clearance for flight was expected by 9 p.m. Dec. 7, Brost said. The goal of the mission is to place a Dragon capsule into a circular, 300-km. (186-mi.) orbit at an inclination of 34.5 degrees. The nominal mission is for Dragon to make two orbits, during which it will execute a pre-programmed series of maneuvers and systems checkouts, then conduct a re-entry burn and parachute into the Pacific Ocean 500 mi. west of Mexico.
The nozzle was cracked in two areas, about four feet from the bottom, with each area spanning 3-4 in.
“Although made of an exotic refractory alloy metal with a melting temperature high enough to boil steel, this component is geometrically the simplest part of the engine,” Brost says.
The mission is the first of three under SpaceX’s $278 million Commercial Orbital Transportation Services contract with NASA. The launch window opens at 9:03 a.m. EST and extends to 12:22 p.m., the 45th Space Wing’s Office of Public Affairs says in its Launch Hazard Area advisory for mariners.
SpaceX’s Florida launch site is Complex 40 at Cape Canaveral Air Force Station.
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