ISTAT Jetrader - Spring 2020 - 43

for MIT/IL, outlined control of the
development process for the GSOP -
and hints at the extensive testing
and retesting done on the software.
The successful management of GSOP
contributed to Apollo 11's success.
The exhaustive testing and
retesting processes were peppered
with what-ifs demanded of software
in space, according to MIT/IL's James
Kernan. While the software wasn't
explicitly tested for the scenario that
unfolded on 20 July 1969 with the
priority alarms sequence causing
brief consternation, the robustness
of GSOP ensured a confidence in
that LM software could complete all
tasks required to return the Apollo 11
astronauts from the moon.
I bonded with my grandfather
reading his plan, with three-letter
acronyms (PCR = program change
request; PCN = program change notice;
SCB = software configuration board,
etc.) sprinkled liberally throughout as
bureaucratic processes shorthand.
Back-and-forth drafting of the document
was much like a bank would debate
wording intended for regulatory eyes, the
primary purpose being to paper decision
flow in the event of mission-impairing
software errors during the Apollo
missions - to dissect what happened.
Few may have seen the plan since
its publication in 1968, as no critical
software errors occurred over the
course of the 12 Apollo missions.
Considering for critical stretches the
astronauts had no radio contact with
Earth and were wholly reliant upon
the AGC to guide the module, this
becomes incredible.
All the more amazing when reading
Bill Tindall's September 1966 memo,
where he shared concerns regarding
"the tremendous amount of work
the astronaut must perform to use
the computer program ... by giving
the crew capability to control what
the computer is doing, as opposed
to having performed automatically."
Well, what was the alternative?
Tindall wasn't advocating scrapping

It must have been extraordinarily satisfying to
witness a lifetime of work culminate into one successful
mission on 20 July 1969.
the AGC design but forcing MIT/IL's
programmers to put themselves in the
user's boots miles from Earth and think
through solutions to problems not yet
encountered in space.

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For the Draper Labs engineers and
all their colleagues, it must have been
extraordinarily satisfying to witness
a lifetime of work culminate into one
successful mission on 20 July 1969. 

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