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Descent and Recovery

The recovery sequence begins with the operation of the high-altitude baroswitch, which triggers the functioning of the pyrotechnic nose cap thrusters. This ejects the nose cap, which deploys the pilot parachute. This occurs at 15,704 feet altitude 225 seconds after separation. The 11.5-foot-diameter conical ribbon pilot parachute provides the force to pull the lanyard activating the zero-second cutter, which cuts the loop securing the drogue retention straps. This allows the pilot chute to pull the drogue pack from the SRB, causing the drogue suspension lines to deploy from their stored position. At full extension of the 12 95-foot suspension lines, the drogue deployment bag is stripped away from the canopy, and the 54-foot-diameter conical ribbon drogue parachute inflates to its initial reefed condition. The drogue disreefs twice after specified time delays, and it reorients/stabilizes the SRB for main chute deployment. The drogue parachute can withstand a load of 270,000 pounds and weighs approximately 1,200 pounds.

After the drogue chute has stabilized the vehicle in a tailfirst attitude, the frustum is separated from the forward skirt by a charge triggered by the low-altitude baroswitch at an altitude of 5,975 feet 248 seconds after separation. It is then pulled away from the SRB by the drogue chute. The main chutes' suspension lines are pulled out from deployment bags that remain in the frustum. At full extension of the lines, which are 204 feet long, the three main chutes are pulled from the deployment bags and inflate to their first reefed condition. The frustum and drogue parachute continue on a separate trajectory to splashdown. After specified time delays, the main chutes' reefing lines are cut and the chutes inflate to their second reefed and full open configurations. The main chute cluster decelerates the SRB to terminal conditions. Each of the 136-foot-diameter, 20-degree conical ribbon parachutes can withstand a load of 180,000 pounds and weighs 2,180 pounds. The nozzle extension is severed by pyrotechnic charge either at apogee or 20 seconds after low baroswitch operation.

Water impact occurs 295 seconds after separation at a velocity of 81 feet per second. The water impact range is approximately 140 miles off the eastern coast of Florida. Because the parachutes provide for a nozzlefirst impact, air is trapped in the empty (burned out) motor casing, causing the booster to float with the forward end approximately 30 feet out of the water.

The main chutes are released from the SRB at impact using the parachute release nut ordnance system. Residual loads in the main chutes deploy the parachute attach fittings with the redundant flotation tethered to each fitting. The drogue and frustum; each main chute, with its flotation; and the SRB are buoyant. The SRB recovery aids are the radio beacon and flashing lights, which become operable at frustum separation. The radio transponder in each SRB has a range of 8.9 nautical miles (10.35 statute miles), and the flashing light has a nighttime range of 4.9 nautical miles (5.75 statute miles).

Various parameters of SRB operation are monitored and displayed on the orbiter flight deck control and display panel and are transmitted to ground telemetry.

The prime contractor for the SRB motors is Morton Thiokol Corporation, Wasatch Division, Brigham City, Utah. United Space Booster Inc. Booster Production Company is prime contractor for SRB assembly, checkout and refurbishment for all non-solid-rocket-motor components and for SRB integration. Companies supplying various components for the SRBs are Pioneer Parachute Co., Manchester, Conn. (parachutes); Abex Corp., Oxnard, Calif. (hydraulic pumps); Arde Inc., Mahwah, N.J. (hydrazine fuel modules); Arkwin Industries Inc., Westbury, N.Y. (hydraulic reservoirs); Aydin Vector Division, Newtown, Pa. (integrated electronic assemblies); Bendix Corp., Teterboro, N.J. (integrated electronic assemblies); Consolidated Controls Corp., El Segundo, Calif. (fuel isolation valves, hydrazine); Eldec Corp., Lynnwood, Wash. (integrated electronic assemblies); Explosive Technology, Fairfield, Calif. (CDF manifolds); Martin Marietta, Denver, Colo. (pyro initiator controllers); Moog Inc., East Aurora, N.Y. (servoactuators); Sperry Rand Flight Systems, Phoenix, Ariz. (multiplexers / demultiplexers); Teledyne, Lewisburg, Tenn. (location aid transmitters); United Technology Corp., Sunnyvale, Calif. (separation motors); Sundstrand, Rockford, Ill. (auxiliary power units); Motorola Inc., Scottsdale, Ariz. (range safety receivers).

Curator: Kim Dismukes | Responsible NASA Official: John Ira Petty | Updated: 04/07/2002
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