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200 Tankings and Counting
In 1976, our country marked its bicentennial celebration with fireworks and fanfare. Thirty years later, NASA's Space Shuttle Program marked its own exciting milestone -- the 200th combined liquid oxygen/liquid hydrogen loading of an external tank, prior to the launch of mission STS-115.

External Tank 200th tanking group gathered in Firing Room 4.After the launch, the "tanking" team gathered around a special banner in Kennedy Space Center's Firing Room 4 to commemorate the event.

Image right: The team responsible for loading liquid oxygen and liquid hydrogen into the shuttle's external tank gather to celebrate the 200th propellant loading. Image credit: NASA/KSC
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"It's times like these that remind me we're living the good old days right now," said Diane Stees, the liquid hydrogen lead engineer for NASA's external tank cryogenic systems in the fluid systems division. "I feel very fortunate to support this milestone in the shuttle program, especially in the company of such an outstanding external tank load and launch team."

Pete Klonowski, United Space Alliance external tank cryo-engineering manager, said few people have worked external tank loading since the start of the shuttle program. "Only about a dozen people in each system have worked as the lead console engineer during tanking and launch," Klonowski added.

Delma Amorim-Pichardo was a software engineer for Martin Marietta external tank operations during STS-1. She was one of several who developed and implemented the liquid hydrogen (LH2) and liquid oxygen (LO2) loading and launch software. "The launch of STS-1 was very exciting for all of us," Pichardo said. "I remember our office walls being wallpapered with printer plotter data for us to analyze.

"We were so motivated, we forgot about going home. Some of the engineers slept on their desks," Pichardo reminisced. Today she is a hardware engineer for the LH2 system.

"We worked the technical issues in real time," said Fred Lockhart, a propulsion staff engineer with Lockheed Martin Space Systems Company. "The software loadings have evolved and improved to accommodate launch vehicle changes."

The external tank and solid rocket boosters for STS-115For STS-1, he was the LH2 console lead engineer for loading preps and post-launch securing.

Image left: During STS-115 launch preparations at Launch Pad 39B, the looming external tank (center) flanked by the solid rocket boosters hide Space Shuttle Atlantis, behind them. Near the top of the external tank is the liquid hydrogen vent arm. Image credit: NASA/Jack Pfaller

Mark Dezendorf worked for Martin Marietta during STS-1. He was in the Launch Control Center Firing Room 1 as the LH2 lead console operator. In 1977, during his work as a field engineer, he wrote software coding for the sequencer program that performed LH2 replenishment of the external tank and managed the terminal count activities for LH2.

Dezendorf is now the cryo simulation lead for USA ground operations engineering process integration, and is co-chairman of the Application Software and System Software Technical Review Panels. He also serves as the engineering team lead for LH2 and LO2 in Firing Room 2 during launch countdown.

"It's great that we've reached this milestone, but you can never take anything for granted," Dezendorf said. "That's why we train and rehearse, run loading simulations and desktop run-throughs of the procedures."

According to Stees, approximately 240,000 gallons of liquid oxygen and 475,000 gallons of liquid hydrogen are pumped from storage tanks into the external tank during the tanking process. Some liquid hydrogen is used to pre-chill fuel lines and the hydrogen compartment of the tank; during fueling, some boils off as a gas. More liquid oxygen than the actual capacity of the compartment is also required. The entire tanking process takes from 2.5 to 3 hours to complete.

Ed DiCristina, USA lead system engineer for the mobile launch platforms' LO2 and LH2 systems, said one of the highlights of his career was the first shuttle launch. Since that time, he's been a member of the LO2 loading team. "As I approach retirement age, I look back at my years here and the many truly wonderful people I've worked with and I can honestly say, 'Oh, what a ride!' "

Klonowski said approximately 36.1 million gallons of liquid oxygen and about 60 million gallons of liquid hydrogen have been used for 200 tankings. That amount of liquid oxygen would fill the Washington Monument 219 times, while the liquid hydrogen would fill the monument 365 times, or once every day for a year.
Linda Herridge, Staff Writer
NASA's John F. Kennedy Space Center