"6_2_15_4.TXT" (3096 bytes) was created on 11-02-87 SOLID ROCKET BOOSTERS Prior to launch, the entire weight of the Space Shuttle is supported on the launch pad by two solid rocket boosters. Each booster is attached to the pad by four large bolts. The heart of each booster is the motor, the largest solid rocket ever to be flown and the first designed for reuse. It is made of four factory prepared segments filled with propellant at the manufacturer's facility and assembled at the launch site. The segmented design permits ease of fabrication, transportation and handling. The motor segments are loaded in pairs from one batch of propellant ingredients to minimize any thrust imbalances between boosters used for a single Shuttle flight. Propellant loading is also done in such a manner as to cause a reduction in thrust 55 seconds into the Shuttle flight to prevent overstressing the Shuttle vehicle during its critical phase of flight, the period of maximum dynamic pressure. Each booster develops approximately 11.8 million Newtons (2.65 million pounds) of thrust. The exhaust nozzle in the aft segment of each motor, in conjunction with the orbiter main engines, steers the Shuttle during flight. It can be moved up to eight degrees by the booster thrust vector control system which is controlled by the orbiter guidance and control computer. At burnout the two solid rocket boosters are separated from the external tank by pyrotechnic (explosive) devices and moved away from the Shuttle vehicle by eight separation motors -- four housed in the forward compartment and four mounted on the aft skirt. The separation motors are fired by a command from the orbiter. The recovery system, in the forward section of the booster, consists of parachutes and a homing device. Following separation -- at about 5.8 kilometers (19,000 feet) -- the booster is slowed by a drogue parachute and finally by three main parachutes to impact water at a speed of about 25 meters/second (85 feet/sec), aft end first. By entering the water this way, the air in the empty booster is trapped and compressed, causing the booster to float with the forward end out of the water. After divers insert a nozzle closure and force the water from the booster using air pumps, the booster is towed to shore. After recovery, the booster is disassembled and refurbished. The motor segments are shipped to the manufacturer for reloading for another Shuttle flight. The other systems are refurbished either at the launch site or at the respective manufacturers' locations. Solid Rocket Booster Length 45.5 meters (149.1 feet) Diameter 3.7 meters (12.2 feet) "6_2_15_9.TXT" (7048 bytes) was created on 11-28-88 SPACE SHUTTLE SOLID ROCKET BOOSTER RETRIEVAL SHIPS When the Space Shuttle's two solid rocket boosters (SRBs) burn out just over two minutes after shuttle liftoff, the rockets separate from the external tank and fall toward the Atlantic Ocean. Unlike SRBs previously used in the space program, the rocket casings and associated flight elements are recovered so that they can be reloaded with propellant and reused. The boosters are retrieved about 258 kilometers (160 miles) downrange by two identical retrieval ships leased by NASA. The ships, Liberty Star and Freedom Star, were built at the Atlantic Marine Shipyard at Fort George Island near Jacksonville, Fla., and leased by NASA. SRB separation is at 49.7 kilometers (30.8 miles), but the spent boosters' momentum continues to carry them upward for 70 more seconds to an altitude of 67 kilometers (41.6 miles) before they begin to freefall into the Atlantic. During the fall, at 4.7 kilometers (2.9 miles) altitude, the nose cap is jettisoned, and a drogue parachute deploys from the frustum, the truncated cone-shaped structure near the forward end of the boosters. At an altitude of two kilometers (1.24 miles), the frustums separate from the boosters' forward skirts, releasing the three main parachutes on each booster that carry the main sections of the casings down to the sea. The SRBs splashdown in an area about 11 by 17 kilometers (7 by 10 miles). Impact velocity is about 97 km/h (60.7 miles per hour). Impact time is just over seven minutes after liftoff. The waiting ships are each 53.6 meters (176 feet) long. Beam is 11.3 meters (37 feet), and they are 4.6 meters (15 feet) deep from main deck to keel. They draw 3.7 meters (12 feet) of water and displace 955.9 metric tons (1,052 tons) each. Of molded steel construction, each is powered by two diesel engines that produce a total of 2,900 horsepower. At sea they can cruise at 27 km/h (17 miles per hour), and can carry fuel for a range of 11,104 km (6,900 miles). Each can carry food and water for 30 days. Ten of each ship's complement are operating crew and nine are retrieval specialists. Also part of each crew is a representative of KSC's STS Processing Directorate. Technical observers can also be carried. Electrical power is supplied by two 165-kilowatt generators, backed up by a four-kilowatt emergency generator. Steerage is by rudder and the maneuvering capability inherent in twin, variable-pitch screws. This is augmented by a 425-horsepower bow thruster providing port/starboard thrust and a stern water-jet thruster which can be directed through a full 360-degree circle. Each ship can apply a towing pull of 27,216 kilograms (60,000 pounds or 30 tons). An SRB casing, after the fuel is exhausted, weighs 74,840 kilograms (165,000 pounds). Its three parachutes each weigh 680 kilograms (1,500 pounds) dry and about twice that when wet. The frustum weighs 2,270 kilograms (5,000 pounds) and its drogue weighs 499 kilograms (1,100 pounds) dry. The spent SRB casings carry radio signaling devices that allow the ships to home in on their locations. The main parachutes and frustum drogue combination are located visually. The main parachutes are the first items to be retrieved. Their winch lines are wound onto three of the four reels on deck. Each reel is 1.7 meters (5.5 feet) in diameter. The drogue parachute attached to the frustum is reeled in the same way until the frustum is approximately 30 meters (100 feet) from the ship. Then the chute's shroud lines are wound in until the frustum can be hoisted from the water by the nine metric ton (10-ton) capability deck crane. Recovery of the SRB casings is the final retrieval operation. As the water is displaced, the casings rise so that they can be towed horizontally. After recovery at sea, the SRBs are towed to Port Canaveral for complete dewatering and then to the disassembly location at Hangar AF on the eastern shore of the Banana River on Cape Canaveral Air Force Station. Depending upon weather conditions and sea states, the recovery and towing operations normally take two days. The Banana River is a shallow arm of the sea which is populated by manatees, or sea cows - an endangered species. To avoid injuring the manatees, the retrieval ships use the diesel-driven waterjet stern thrusters for traveling on inland waterways. The bow thrusters can also be used. While waterjets are not new, the Liberty Star and Freedom Star are believed to be the first and only vessels in which this propulsion system has been used to protect the ungainly sea cows from injury by conventional propellers. The ships are also suited for other uses, including mapping the ocean floor for seismographic studies, underwater search and research. They may be used for those purposes when not required for NASA missions. SRB Retrieval Ships Liberty Star and Freedom Star Length 53.6 meters (176 feet) Beam 11.3 meters (37 feet) Depth 4.6 meters (15 feet) (main deck to keel bottom) Draft 2.7 meters (9 feet) to 3.9 meters (12 feet 8 inches depending on load conditions Construction Molded steel hull Propulsion at sea Two General Motors (EMD) 12-645E6A diesel engines, combined 2,900 hp., with Lufkin gears and Lips control lable pitch propellers Propulsion and maneuvering in inland waterways One 425 hp. White Gill waterjet stern thruster, driven by 8V71turbo-intercooled (TI) Detroit diesel engine Maneuvering One 425 hp. Schottel bow thruster, driven by 8V71 turbo-intercooled (TI) Detroit diesel engine Auxiliary power Two 165 kw Kato generators and one 4 kw Kohler emergency generator Towing pull 27,216 kg. (60,000 pounds or 30 tons) Displacement 955.9 metric tons (1,052 tons) 660 to 1140 long tons depending on load condition Normal cruising speed 24 km/hr (17 mph or 15 knots) Range 11,104 km (6,900 miles) Endurance Food and water for 30 days Complement 10 crewmen and 9 retrieval specialists, plus technical observers. Total berthing: 24 persons Retrieval support equipment Diver operated plug, barb, pump and associated dewatering gear. One Quincy QR100 air-cooled, two-stage air compressor (for nozzle plug operation) UHF, VHF, HF and SATCOM communications equipment One Model 410 Hallmark-Prentice deck crane, 9 metric ton (10 ton) capacity (for frustum retrieval) Four parachute reels One towing winch and one H-bit (for securing tow line) for towing one solid rocket booster casing with nozzle One air hose reel