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Cryogenics and Fluids Branch

SHOOT Out At Kennedy Space Center

By Tom Hait


Cryorats group emblem D When we arrived at Cape Canaveral’s Hanger A-E the morning of February 10th, 1993, some of the team members had already staked their claim on office space with cardboard nameplates. This would be the first stop for the Superfluid Helium On-Orbit Transfer (SHOOT) payload on its way to Kennedy Space Center. The whole room was buzzing -- smiles, handshakes, and "high-fives" abound. At 9am the conference room was packed; most of the faces were familiar, but many were new to us. We went around the room, stating our name and purpose for being there. Then the managers proceeded with the formal briefings, protocols and schedules. All of this was fine, but I still couldn’t wait to see the star of the show arrive.

SHOOT dewars mounted to frame which rests on floor. D
The call came just before noon. The truck carrying the experiment consisting of two large liquid helium-filled tanks and a complex array of tubing, valves, and sensors was only 20 miles away. It slowly maneuvered its way to the back of the building near the entrance to the clean room facility. When the truck door was opened, it was apparent that the payload had shifted during transit. Fortunately, a thorough inspection revealed no damage to any flight hardware! The rest of the afternoon was spent gently moving the two ton baby from truck to truck. Soon after the flatbed truck was in the clean room, the overhead crane hooked-up to the lifting straps, and delicately placed the payload on the floor. This would be SHOOT’s home for the next couple of weeks.

SHOOT dewars, covered with metal
foils, sitting on mobile framework.
Our first problem came as we were removing protective wrapping from the payload. One of the technicians noticed a hand valve partially opened, and quickly closed it. However, an ice plug had already formed inside the high flow vent line, and the dewar would have to be warmed up to allow the frozen air to melt. This is a risky procedure, because the temperature must rise from 4.2 Kelvin (K)(-269 C or -452 F) to about 80 K (-193 C, -315.7 F). The increasing pressure inside the tank could cause the emergency burst disks to rupture, setting us back weeks in an already tight schedule. Skillfully, our team crossed this hurdle with no damage to hardware. The ongoing job now was to keep the dewars cold by periodically filling with liquid helium.

Overhead view of SHOOT with worker
I was a member of Cryogenic Servicing Team #1, Steve G. was assigned to Team #2, and Jim T. worked with either team, alternating with the other two project scientists. As we had come to find out, every cryogenic servicing job was different in setup. In the Hanger A-E clean room, the payload sat horizontally, with plenty of open space to manipulate the 2-3 inch diameter, vacuum-jacketed, flexible steel lines. Each line was 20-30 feet long, requiring support to relieve stress on the supply dewar siphon and flight dewar fill and vent ports. When the payload moved to the Vertical Processing Facility (VPF) in late February, the servicing took on a new complexity.

SHOOT dangling in midair.
D Now secured to the Hitchhiker bridge, the SHOOT payload was mounted to support beams 75 feet above the VPF floor. KSC personnel surrounded the payload with sturdy platforms and scaffolds to allow continued access. In addition to our cryogenic safety gloves, face masks, and aprons, the VPF required full clean room bunny suits, as well as tethering of all tools and equipment. The lines were somewhat easier to stage because there were numerous support beams, rails, and overhead platforms to tie to. The dewars were now sitting vertically, so the time between fills increased from several days to several weeks. Despite these obstacles and constraints, the servicing went very well. We even conducted successful transfer tests with our assigned astronauts, Mission Specialists Janice Voss and Jeff Wisoff. At the beginning of April, SHOOT was loaded into the Payload Canister, a clean, environmentally controlled container the size of the shuttle bay.

Shuttle Endeavour on the crawler
The Payload Canister was transported to Launch Complex 39 Pad B, where it was attached to the Payload Changeout Room (PCR). There, while maintaining the cleanliness level, the payload was transferred to the PCR, and the Canister was taken away. The PCR rendered its own challenges, with tighter working space, less tie points to secure the lines, and stricter tool control than the VPF. In addition, headsets were needed to communicate with team members during servicing because of the high background noise and line-of-sight impediments. Again, the team prevailed, completed one successful fill after another as delays in the shuttle launches kept us waiting. In the middle of April the Endeavour rolled up to Pad B, and the SHOOT payload was installed into the bay. With the launch scheduled for June 20th, Steve, Jim, and I headed to Kennedy to participate in the most crucial servicing work of the project.

Workers in cleanroom suits servicing SHOOT.
D To prepare for the last cryogenic procedure before flight, the low temperature top-off, the flight dewars and the 1000 liter dewars were topped off with liquid helium. The low temperature top-off requires pulling a vacuum on the liquid helium tanks, which lowers the temperature to less than 2 K. On Tuesday, June 15th, we began 12 hour shifts to monitor the huge, noisy pumps that were pumping on the dewars. That Thursday morning we were ready to begin the low temperature top-off at about 10:30am. Suddenly, a fire alarm sounded, and a voice over the PA ordered everyone out of the PCR! We ran down seven flights of stairs, still fully dressed in our clean room bunny suits, into the 90 degree sunshine. We hurried over to our boxcar office at the base of the pad, waiting for instructions from the Pad Leader. After a few moments, the false alarm was cleared, and we returned to the PCR. After that little scare, the low temperature top-off went without a hitch.

Overall view of Shuttle payload bay, including SHOOT.
The final task before clearing out of the PCR was the payload closeout, which includes making electronic connections, adding thermal blankets, removing ground support parts, and lock wiring bolts. Everything proceeded smoothly through the afternoon, until a 4 inch piece of lock wire was lost near the payload. With the launch in danger of slipping, everyone available searched around and below the payload for the braided steel wire. After a couple hours, I found the wire resting on the reflective blanket covering the SHOOT Auxiliary Power Unit (APU) box. With that issue closed, the pad was cleared, and we awaited the launch of STS-57.

On Sunday morning, Steve G. and I boarded the VIP bus bound for the Banana Creek Viewing Area -- just 3.2 miles from Pad B. As the countdown stalled and the weather failed to improve, it became apparent that the launch would be delayed. Making our way back to the bus, we talked for the first time about possibly missing this launch. Later that evening I started packing. My flight home was scheduled for tomorrow evening. Endeavour had to launch Monday morning!

Shuttle launch.
We were at the Spaceport bus stop at 7am. The weather looked much better today than Sunday. We staked out our spots at the viewing area. I set up my camcorder just behind the short fence in front of the bleachers. The countdown continued. Every countdown hold time we passed brought clapping and cheers from the spectators. Finally, the last ten seconds were counted off, and the Endeavour lifted off the pad. We waited, then the sound and vibration from the solid rocket boosters hit the viewing area. It was the most spectacular event I've ever witnessed. The feeling was indescribable, made even sweeter by the fact that something we worked on with our hands was going for the ride!

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Curator: Brent Warner
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Last Updated: November 4, 2004