ISTAT Jetrader - Spring 2020 - 36

Control (Free Fall)

Command and service module (CSM) showing control system
thrusters' adjustments along the pitch, roll and yaw.

Inertial Guidance,
Improvisation, Attitude:

What Guided Us
to the Moon
Developing the guidance, navigation and control
system for the Apollo spacecraft.
by Benjamin Millard

36

* T H E O F F I C I A L P U B L I C AT I O N O F I S TAT

I

n many ways, the guidance,
navigation and control
(GNC) system devised by
Massachusetts Institute of
Technology's Instrumentation
Labs (MIT/IL, what is today
Draper) is as groundbreaking
as landing on the moon itself.
MIT/IL was awarded the first
Apollo contract by NASA in 1961 to
design Apollo's command and service
module (CSM) and lunar module's (LM)
computer - called the Apollo Guidance
Computer (AGC) - and its software,
and to subsequently work with the
modules' contractors and astronauts
during the intensive testing phases. The
system would enable Apollo astronauts
to execute complex maneuvers via
inputting a series of commands and data
into an onboard computer - something
never done before.
It was the first-ever "fly-by-wire"
system enabling astronauts to fly the
CSM and LM via an incredibly primitive
computer display and keyboard. An
onboard computer controlled the entirety
of the Apollo spacecraft; astronauts
moved a small joystick, which transmitted
electrical signals to the computer,
conveying instructions to the CSM or LM.
Following his retirement from the
U.S. Navy, and brief stops at Raytheon
and GE, my grandfather, Robert C.
Millard, joined MIT/IL in 1964 as a
director of project management for
Apollo's GNC system. His group was
tasked with the Guidance Systems
Operations Plan (GSOP), melding
system requirements for the various
Apollo constituencies: pilot/astronauts,
subcontractors, NASA and its Manned
Spacecraft Center (MSC) in Houston, and
an extraordinary team of early computer
programmers housed at MIT/IL.
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. It says
everything that "joystick flying" earned

Photo courtesy of Draper.

AVIATION HISTORY
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