300
270
250
(^220200)
120
100
75
Little West Crater Double Crater
At mission control,
fuel quantity light
comes on, indicating
about 114 seconds
of propellant
is remaining.
Landing radar loses lock,
causing warning lights to flash.
Mission control
starts a 94second
countdown, which
ends in a “bingo” call:
land or abort now.
Dust is blown up
from Little West
Crater; 85 seconds
to bingo call.
75 seconds to bingo
call; Armstrong notes
5 percent of propel
lant is remaining.
Substantial
dust is blown
around by
exhaust
engine;
65 seconds
to bingo call.
20 seconds to bingo call;
contact lights come on;
engines have stopped.
Armstrong reports,
“Tranquility Base here.
The Eagle has landed.”
Mission control responds,
“You got a bunch of guys
about to turn blue! We’re
breathing again. Thanks
a lot .”
Armstrong
continually flicks
on and off the
rateofdescent
switch to control
the Eagle’ s des
cent. He pitches
the vehicle back
to reduce his
forward speed.
1:50 seconds to landing.
TRACKING THE ASTRONAUTS
Armstrong’s “one small step for man” was followed
by many more as he and Aldrin set up equipment and
explored the lunar surface. High-resolution imagery from
the LRO Camera (LROC), displayed here with tracing
for emphasis, shows the disturbed moon dust that the
two astronauts stirred up during the two and a half hours
they moved about Tranquility Base. Much of their travel
involved setting up scientific experiments, including the
Passive Seismic Experiment to detect lunar “moonquakes,”
the Solar Wind Composition Experiment, which collected
samples of the solar wind for later analysis, and the Laser
Ranging Retroreflector, which measured the moon’s orbit
and variations in its distance from Earth. The farthest trip
from the Eagle was an unplanned jaunt that Armstrong
took to the edge of Little West Crater, a distance of
roughly 200 feet.
July 2019, ScientificAmerican.com 59
SOURCES: NASA (
West Crater
and
boulder field
); NASA’S GODDARD SPACE FLIGHT
CENTER (
base map
); THOMAS SCHWAGMEIER AND ERIC M. JONES (
footpath reference
)
Passive Seismic Experiment Package
Discarded cover
Laser Ranging Retroreflector
Double Crater
Lunar module
Solar Wind
Composition
Experiment
Television camera
Little West Crater
NORTH
0 30 feet
Walking direction
Aldrin
Armstrong
Graphics by Edward Bell (landing path) and Eléonore Dixon-Roche ( footpath)