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Solid Rocket Booster Retrieval

IMAGE: A dive team arrives at the site of a floating SRB.

As dawn breaks over the western Atlantic Ocean, a dive team arrives at the site of a floating SRB. See more SRB retrieval photos in the Gallery.

The space shuttle's Solid Rocket Booster, or SRB, casings and associated flight hardware are recovered at sea after each launch and recycled in order to reduce the cost of launches.

The expended boosters are disassembled, refurbished and reloaded with solid propellant for reuse.

The two NASA retrieval ships that perform the SRB recovery, named Liberty Star and Freedom Star, were specifically designed and constructed for this task. Built at Atlantic Marine Shipyard, Fort George Island, near Jacksonville, Fla., in 1980 and 1981, the ships are 53.6 meters (176 feet) in length, 14.3 meters (37 feet) in width and draw 3-4 meters (10-12 feet) of water.

Each ship is designed to retrieve one booster. Each ship's complement includes a crew of 10, a nine-person SRB retrieval team, a retrieval supervisor and observers. The maximum complement is 24 persons.

IMAGE: SRB illustration

Read more about Solid Rocket Boosters.

"The biggest challenge we face during retrieval is weather," said Joseph Chaput, manager of United Space Alliance Marine Operations and captain of the Liberty Star. "We might have to wait out there for days if the weather is too rough. We can't retrieve the SRBs in 20-foot seas."

When the weather cooperates, the team conducts a visual assessment of the flight hardware upon arrival. The pilot parachutes and main parachutes are the first items to be brought onboard. With the chutes and frustum recovered, attention turns to the SRB. The dive team prepares for booster de-watering.

Two small boats, with nine retrieval divers aboard, are deployed. The job of the first dive team is to install an Enhanced Diver-Operated Plug, or EDOP, in the nozzle of the booster. The EDOP is launched from the ship and towed to the booster by one of the small boats. Once dive preparations are complete, the dive team enters the water for EDOP insertion. The EDOP is 7 meters (22 feet) in length and weights 500 kilograms (1,100 pounds). It is slightly buoyant in water, meaning it just floats and is easily guided to the aft skirt at a depth of about 33 meters (110 feet) by the divers. A quick inspection of the nozzle is conducted. The EDOP is then inserted into the booster nozzle. Once the EDOP legs are locked in place and the nozzle sealed, an air hose is attached, which is deployed from the ship.

IMAGE: An SRB retrieval team attaches towlines to a spent booster.

An SRB retrieval team attaches towlines to a spent booster.

The second team double-checks the aft skirt and EDOP installation to ensure there are no problems. After the second dive is completed, de-watering operations begin. Air is pumped from the ship through the EDOP and into the booster, displacing water within the casing.

As the process continues, the booster rises in the water until it becomes top-heavy. It falls horizontally, like a log in the water. Air pumping continues until all water is expelled from the empty casing. The final step in the ocean retrieval procedure is to connect the ship's tow line. Once the tow connection is made, the divers return to the ship, and the trip to NASA's Hangar AF on Cape Canaveral Air Station begins.

The ships enter Port Canaveral, where the booster is changed from the stern tow position to a position alongside the ship, the hip tow position, to allow greater control. The ships then pass through a drawbridge, Canaveral Locks, and transit the Banana River to Hangar AF. The SRBs are lifted from the water with a straddle-lift style crane and placed on rail cars to begin the disassembly and refurbishment process.

In 1998, the Solid Rocket Booster recovery ships took on a new service for NASA. Space Flight Operations contractor United Space Alliance, or USA, streamlined efforts for the Space Shuttle program by taking over the towing of the shuttle's External Tanks from Louisiana to Florida using the Liberty Star and the Freedom Star.

Well-suited for their role supporting space shuttle operations, the Liberty Star and Freedom Star also have proven themselves in other operations. Over the years, both vessels have seen service in side-scan sonar operations, cable-laying, underwater search and salvage, drone aircraft recovery, as platforms for robotic submarine operations and numerous support roles for other government agencies.

"The retrieval vessels are one of the significant tools used to provide reuseable hardware and controlled costs for manned space flight," said USA SRB Operations Director Jim Carleton.

Text and photos for this story were provided by Kennedy Space Center's Spaceport News.

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 06/23/2003
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