|Storytelling with Jack Garman
On Jan. 25, JSC employees gathered to listen as Jack Garman chronicled “Remembrances” from the years 1972 to 1981 through the development of the Shuttle Avionics Software at a Storytelling event. 1972 marked the end of the Apollo program, while 1981 was the year of the first vertical flight, two memorable landmarks in NASA’s history.
Jack Garman, former NASA senior executive, was first noted for his work in the Apollo program, then for his vital role in the birth of the Software Production Facility (SPF). Ultimately, he was known for the notion of "flight to flight" reconfiguration to support the vigorous shuttle launch schedule. Garman held various positions around JSC such as the chief of Data Processing. He also won many awards including the Presidential Medal of Freedom. Garman played a major role in preventing the abort of the STS-1 mission, which he described as a very “frightening” 48 hours, when Garman and others detected a software bug that threatened launch.
Garman started his presentation with “Avionics Reminders” including the complexity of the avionics software “way back then and today” as well as the contrast between redundancy and reliability and how each is necessary to isolate failures. Another “reminder” was the instability of the shuttle at the time. Digital flight control was used full time because the shuttle could not be flown manually, which highlights the importance of computers and automatic failure detection.
The next topic of discussion was the people and business involved with the computer evolution. Garman spoke of huge meetings full of hundreds of engineers and businessman helping to facilitate the software development. He emphasized that they did not have the convenience of e-mail, personal computers or personal phones at this time. Government memorandums were used, and communicating was much more challenging than it is today. In 1972, an operating system was unknown, and Garman joked about the difficulty of explaining his job to his family.
Dr. Chris Kraft, center director at the time, collaborated with Garman to form the newly announced Spacecraft Software Division (SSD). This team included key folks from around the center; the “core” of the Apollo Guidance Program section; and Garman working with the Flight Computer Operating System (FCOS), User Interface (UI), High Order Assembly Language - Shuttle (HAL/s), and other various software development and test tools.
Garman emphasized that developing advanced software was a strenuous process full of trials and tribulations. During the development stage, there were many debates while trying to pinpoint the best way for the software to work. “Accidental insanity” ensued as four computers were meant to synchronously do all the calculations and vote on each other to accomplish Fail Operational/Fail Safe (FO/FS). They also ran into an issue because the software was larger than it needed to be, which created inefficiency. They realized the need for “test software” and went through many stages of the infamous “T&O (Test and Operations) Board,” to decide which changes the software needed.
Garman continued his presentation with the intriguing story of the first orbital spaceflight of the United States Space Shuttle. STS-1 would be the first U.S. manned spaceflight since 1975. He mentioned that there was a tremendous pressure surrounding this flight as he spoke, “the entire focus was on the first flight, to make it work.” However, 20 minutes before the shuttle was scheduled to launch, astronauts and technicians tried to initialize the back-up software system and could not.
“I remember standing in the control center and watching,” Garman said as he recalled the moment. “One of the GPC’s died on the spot. This was very frightening. I was wondering if another one would fail, and another, and another …”
They locked several people in a conference room and discussed the possibility of the primary system failing. The group discovered the problem was due to a glitch in the PASS (Primary Avionics Software System) that kept the Backup Flight Software (BFS) from synching up. Ultimately, Garman and his team decided to delay STS-1.
Forty-eight hours later, the launch happened. Thankfully, everything went well and everyone was thrilled. Garman explained that the probability of an issue such as this occurring was one out of sixty-seven. Unfortunately, the first flight was proof that even though the chance was small, it was still possible. After the landing was complete, Garman wrote a publication explaining the delay. The malfunction during STS-1 became known as “The ‘Bug’ Heard ‘Round the World.”
Garman ended his Storytelling presentation with a question-and-answer. He shared that many things sparked his interest in space at a young age and he began his career at NASA at age 21. Garman also made predictions for the future of computers, commenting that they are getting smaller and faster and that the ability to understand the hardware is becoming a rarity. The Storytelling event gave JSC employees the opportunity to hear about a revolutionary time in NASA’s history from a first-hand source.
Johnson Space Center, Houston