All about the MDD
Sept. 23, 2005
The most extensive overhaul in the 29-year history of Dryden's Mate/Demate Device was completed in 2004, and involved replacing the mammoth structure's original coating of lead-based paint with a fresh coat of non-toxic paint.
Image Right: The Mate/Demate Device is used to lower Discovery onto the host NASA 747 Shuttle Carrier Aircraft, which carried it across the U.S. to Kennedy Space Center, Fla. NASA Photo by Carla Thomas
A team of contractors and NASA personnel collaborated to develop a way of disposing of the lead-based paint removed from the structure by recycling it into commercial cement. The alternative was sending it to a landfill as hazardous waste – all 240 tons of it.
The MDD had not been repainted since it was first built, although it had been retouched. The cost of the new paint job – $2 million – beat the other option: replacing the structure entirely. Replacement costs were estimated at $9 million, according to Joe D'Agostino, Dryden's manager of space shuttle operations.
In developing the contract for the MDD work, D'Agostino said he sought a team approach. Lance Dykhoff, Lockheed Martin's Dryden site manager, called on Lockheed program manager Lou Pustka to help assemble the team.
Specifications were developed and Lockheed, which holds the contract for Dryden shuttle operations, chose Anaheim, Calif.-based Techno Coatings Inc. as its partner for the project. TCI won with a team proposal that blended onsite Lockheed personnel expertise with their company's corporate knowledge and resources for the effort. The result was wholesale recycling of the MDD's old lead-based coating into cement, with the help of an additive called Blastox that mitigates lead content in paint.
Image Left: Discovery is shown inside the Mate/Demate Device. The shuttle was hoisted aloft in the MDD then positioned over the NASA 747 Shuttle Carrier Aircraft. It was then lowered slowly onto the SCA prior to its cross-country journey to Kennedy Space Center. NASA Photo by Tom Tschida
The structure has served NASA well, as Dryden was the primary landing site during the early days of the space shuttle program. About a year before it would hoist Space Shuttle prototype Enterprise onto the NASA 747 Shuttle Carrier Aircraft for the first time, the gargantuan steel frame had been erected and stood ready to do the heavy lifting.
Dryden remains the primary backup landing site when clouds roll in at Kennedy Space Center, Fla., and the weather isn't good enough for a landing there. In all, 50 shuttle landings took place at Dryden, including those of the first nine orbiter flights minus STS-3, in which Columbia landed at White Sands, N.M. That 50-flight total also includes all of the first landings of new orbiters as each joined the fleet.
The MDD consists of two 100-foot towers with stationary platforms every twenty feet from 20 to 80 feet on each tower, and a horizontal structure mounted at the 80-foot level between the two towers. The horizontal unit cantilevers 70 feet out from the main tower units, guiding and controlling a large lift beam that attaches to the orbiters to raise and lower them.
Three large hoists are used to raise and lower the lift beam. Two of the hoists are connected to the aft portion of the lift beam and one hoist is attached to the beam's forward section. The three hoists operate simultaneously. As a unit the hoists can lift 120 tons, or 240,000 pounds, and the average space shuttle weighs in at about 231,000 pounds, D'Agostino said. D'Agostino was originally hired as a shuttle security officer and he recalled the first time the MDD was used.
"The first time we lifted (Space Shuttle prototype Enterprise) during the ALT (Approach and Landing Tests) program took a considerable amount of time, which is to be expected with a new operation," he recalled.
"We had a technical problem (mating Enterprise). The operation lasted almost 14 hours. We got it to the point where we were ready to lower Enterprise onto the 747 and we learned the orbiter didn't fit.
"To make it fit, we moved the forward strut on the 747. It was nerve-wracking."
Image Right: Here is a spectacular view of the Mate/Demate Device at sunrise. NASA Photo by Tony Landis
The second time Enterprise was lifted was much more streamlined and the effort took just six to eight hours, he said. Shuttle landings later required changing work schedules in order to keep staff on site around the clock, until the orbiter was safely mated to the NASA 747 and winging its way back to Kennedy Space Center.
Dryden and Kennedy are home to NASA's two MDDs. Dryden's MDD is more complex than the one at Cape Canaveral, D'Agostino said, because the one here is used as a work site for tasks that, when they are necessary in Florida are accomplished at Kennedy's Orbiter Processing Facility. Dryden's structure is similar to its Florida twin, but the Dryden MDD has elevators and had extra equipment built into it that was required in the early days of the shuttle program. The modifications were made largely to enable the device to meet heavy-lift requirements as the shuttle program progressed.
What started out as one of the world's largest Erector sets became a permanent structure at Dryden as the needs of the space shuttle program changed and required welds, concrete and additional work platforms and heavier lift capability, D'Agostino said. Modifications since the MDD's completion in 1976 have cemented the device into Dryden history – mot just physically but metaphorically as well.