NASA’s first software engineer: Margaret Hamilton - Matt Porter and Margaret Hamilton

View full lesson: https://ed.ted.com/lessons/the-software-that-sent-humans-to-the-moon-matt-porter-and-margaret-hamilton

The Apollo 11 moon landing was about the astronauts, mission control, software and hardware all working together as a seamless integrated system. None of which would have been possible without the contributions of one engineer: Margaret Hamilton. Who was this pioneer? Matt Porter and Margaret Hamilton detail how a woman and her team launched the software that took mankind to the Moon.

Lesson by Matt Porter and Margaret Hamilton, directed by TOTEM Studio.

At roughly 4pm on July 20, 1969,

mankind was just minutes away
from landing on the surface of the moon.

But before the astronauts
began their final descent,

an emergency alarm lit up.

Something was overloading
the computer,

and threatened to abort the landing.

Back on Earth, Margaret Hamilton
held her breath.

She'd led the team developing
the pioneering in-flight software,

so she knew this mission
had no room for error.

But the nature
of this last-second emergency

would soon prove her software
was working exactly as planned.

Born 33 years earlier in Paoli, Indiana,
Hamilton had always been inquisitive.

In college, she studied mathematics
and philosophy,

before taking a research position at the
Massachusetts Institute of Technology

to pay for grad school.

Here, she encountered her first computer
while developing software

to support research
into the new field of chaos theory.

Next at MIT's Lincoln Laboratory,

Hamilton developed software
for America’s first air defense system

to search for enemy aircraft.

But when she heard
that renowned engineer Charles Draper

was looking for help
sending mankind to the moon,

she immediately joined his team.

NASA looked to Draper and his group
of over 400 engineers

to invent the first compact
digital flight computer,

the Apollo Guidance Computer.

Using input from astronauts,

this device would be responsible
for guiding, navigating

and controlling the spacecraft.

At a time when unreliable computers
filled entire rooms,

the AGC needed to operate
without any errors,

and fit in one cubic foot of space.

Draper divided the lab into two teams,

one for designing hardware
and one for developing software.

Hamilton led the team that built
the on-board flight software

for both the Command and Lunar Modules.

This work, for which she coined the term
“software engineering,"

was incredibly high stakes.

Human lives were on the line,
so every program had to be perfect.

Margaret’s software needed to quickly
detect unexpected errors

and recover from them in real time.

But this kind of adaptable program
was difficult to build,

since early software could only process
jobs in a predetermined order.

To solve this problem,

Margaret designed her program
to be “asynchronous,”

meaning the software's more important
jobs would interrupt less important ones.

Her team assigned every task
a unique priority

to ensure that each job
occurred in the correct order

and at the right time—
regardless of any surprises.

After this breakthrough,

Margaret realized her software
could help the astronauts work

in an asynchronous environment as well.

She designed Priority Displays

that would interrupt
astronaut’s regularly scheduled tasks

to warn them of emergencies.

The astronaut could then communicate
with Mission Control

to determine the best path forward.

This marked the first time flight software
communicated directly—

and asynchronously—
with a pilot.

It was these fail safes that triggered
the alarms just before the lunar landing.

Buzz Aldrin quickly realized his mistake—

he’d inadvertently flipped
the rendezvous radar switch.

This radar would be essential
on their journey home,

but here it was using up
vital computational resources.

Fortunately, the Apollo Guidance Computer
was well equipped to manage this.

During the overload,
the software restart programs

allowed only the highest priority jobs
to be processed—

including the programs
necessary for landing.

The Priority Displays
gave the astronauts a choice—

to land or not to land.

With minutes to spare,
Mission Control gave the order.

The Apollo 11 landing was about
the astronauts, Mission Control,

software and hardware all working together
as an integrated system of systems.

Hamilton’s contributions were essential
to the work of engineers and scientists

inspired by President John F. Kennedy’s
goal to reach the Moon.

And her life-saving work
went far beyond Apollo 11—

no bugs were ever found in the in-flight
software for any crewed Apollo missions.

After her work on Apollo,

Hamilton founded a company that uses
its unique universal systems language

to create breakthroughs
for systems and software.

In 2003, NASA honored her achievements
with the largest financial award

they’d ever given to an individual.

And 47 years after her software
first guided astronauts to the moon,

Hamilton was awarded
the Presidential Medal of Freedom

for changing the way we think
about technology.