ISTAT Jetrader - Spring 2020 - 37

The Character of Draper
AGC creators were a more diverse
group than perhaps springs to mind
the 1960s American workforce, where
another Draper - Don of Madison
Avenue - overwhelms the popular
image. Dr. Charles Draper was an
MIT professor who had pioneered
the use of inertial guidance systems
on Navy gunships during WWII. By
all accounts, he thought out of the
box and diametrically opposed to
the stereotypical bureaucracy of
government-led space programs.
From MIT/IL's winning of the Apollo
contract in 1961 until 1965, Draper kept
the project's organization extremely
informal to foster creative thinking.
Draper was approachable, caring and
loving of his colleagues - tough love at
times, forcing the engineers to think on
their feet and use intellect to improvise
effective solutions to the multifold
challenges of the AGC task.
The MIT/IL software engineering
division was led by Presidential Medal
of Freedom award recipient Margaret
Hamilton. She was lead programmer on
AGC and led the team that developed
onboard flight software for CSM and LM.
Draper's website states Hamilton's work
"is the base of what today is an industry
of software engineers who owe their
careers to Dr. Hamilton and their team."
One story shows Hamilton carrying
forward the Apollo mission with "cando" and "ad-hoc" qualities. Needing to
flag a serious shortfall to the software
that she had discovered but wasn't
authorized to recode (as per MSC
directive), Hamilton wrote clearly: "Do
Not Select P01 (for Pre-Launch) During
Flight." Selecting P01 would wipe
clean all the stored navigation data
needed to complete whatever maneuver

A guidance and navigation control system via
digital computer needed to work flawlessly, with
astronauts' complete confidence in such system, because
to misfire one engine or misread one sensor might flip the
mission to a failure, or even disaster.
the astronaut was attempting. (This
happened on the Apollo 8 mission,
leading NASA and MSC to authorize a
recode, which Hamilton had suggested
much earlier on.)
MSC Director of Flight Operations
Bill Tindall's memos as the person
responsible for all guidance and
navigation computer software developed
by MIT/IL are publicly available and
amazingly document this systems'
entire evolution via neatly typed letters
(available at Draper, "TindallGrams").
Tindall posed remarkably basic
questions to Apollo workgroups with
much humor, giving the impression of
a joyous endeavor, notwithstanding his
great responsibility and the awareness
of reaching for the unknown.

Having been asked whether the
astronaut, upon first powering up the
AGC, had the needed erasable memory
contents needed to get to the moon,
Tindall dryly noted "Is anyone within
the sound of my voice working on that?
In fact, who is supposed to?" Tindall
may have meant himself, or could
have alluded to the MIT/IL engineers
in Cambridge, Massachusetts (himself
being in Houston), who presumably had
thought of that well before.

Maneuvering Through
Space via a Computer
(and a Human)1
Working within extreme computing
limitations, MIT/IL engineers needed

Photo courtesy of Millard Family.

the astronaut's confidence so much
that Neil Armstrong himself helped
sell the U.S. Air Force on the idea of
transitioning its in-production fighters
to digital fly-by-wire in the early 1970s
based on his Apollo experience.

The author's grandfather's Apollo Achievement Award.
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