|Support. Modular towers equipped with canister jacks shore up the RSS on 39A while it gets structural steel reinforcement. (Photos courtesy of Barnhart Crane & Rigging Co.)|
The U.S. National Aeronautics and Space Administration is about to kick-start its space shuttle program after more than 28 months stuck on Earth. Heavy-duty upgrades to Kennedy Space Center, including jacking up two giant launch structures weighing several thousands of tons, are preparing astronauts for a space shuttle launch scheduled for this summer.
At the launch complex located on Merritt Island, Fla., contractors are engaged in an intricate program of corrosion control and steel reinforcement required by NASAs new "Return to Flight" safeguards. The Discovery liftoff, scheduled mid-to-late July, would be the first space shuttle to fly since the Columbia disaster grounded the fleet two years ago (ENR 2/10/03 p. 11).
The actual weight of the two launch towers, termed "39A" and "39B," had never been measured in their 30-plus years of operation, so "the first thing was to get Pad B ready for return to flight," says Michael H. Olka, a project manager for United Space Alliance LLC, Houston. The company, a joint-venture of Boeing Co. and Lockheed Martin Corp., is NASAs prime contractor for the space shuttle program. Discovery is to take off from Pad 39B.
In January 2004, Buffalo Hydraulic, a Buffalo, N.Y.-based subcontractor, positioned 21 lifting jacks under 39Bs Rotating Service Structure, a 102-ft-long, 50-ft-wide and 130-ft-high mass of tubular steel that swings 120° on rail trucks to enclose the space shuttle while it is fitted with payload. The RSS hinges to a Fixed Service Structure, a roughly 40-ft-square steel tower in plan that is nearly twice as tall as the RSS. Both stand on an octagonal concrete pad. The subcontractor lifted the RSS by about 1 in., measured the hydraulic pressure at each point and accounted for the jacks footprints. The operation "was the first time we jacked the RSS" in history, says Kevin W. Ivey, president of local general contractor Iveys Construction Inc.
Computing the mass of the RSS on launch pad 39A was done in February 2004. The results for both structures came in at a combined 5,311 tons. Engineers found that over the years, the towers were loaded well above their design.
USAs team remedied the safety problem by jacking up the steel structures again and installing a new upper-bearing race assembly. Workers finished the up-fit on 39A this past January and 39B in March. The 3-ft-dia. brass race fits into an upper hinge column where the RSS pivots against the FSS.
Last August through January, workers sandblasted the RSS on 39B using a crushed coal slag called "Black Beauty" at 90 psi. Then, the RSS received an inorganic zinc topped with portland cement-based paint. "We blasted and painted 600,000 sq ft of steel," says Harry Moore, USAs manager of corrosion control.
Similar work on 39A is slated to wrap in January 2006 after NASA completes a project to beef up structural members. At this time, the RSS on 39A is jacked up on three modular towers designed by Barnhart Crane & Rigging Co., Memphis, Tenn., while Iveys reinforces the structure with 1 / 2-in. steel plate. The towers are scheduled to release the 2,500-ton load on July 20.
Correction: A recent story about repairs to Kennedy Space Center contained an error (ENR 6/13 p. 16). The general contractor for replacing bearing assemblies and weighing the launch towers was Industrial Steel Inc., Titusville, Fla., with Buffalo Hydraulic as its subcontractor.