Apollo Expeditions to the Moon
CHAPTER 8, Appendix
Protecting Men for Their Steps on the Moon
The lunar environment is hostile to man. It lacks
oxygen and water; it is too hot in the day's sunshine (250° F)
and too cold in the night's darkness (-250° F).
Hazardous micrometeoroids and
space radiation dart about. With no atmosphere
and therefore no atmospheric pressure, fluids
in an exposed human body will boil on the Moon.
How can man survive, much less operate, in such
an unfriendly environment? Answer: by taking
his own friendly environment with him in the
form of a spacesuit.
The spacesuit, or Extravehicular Mobility Unit
(EMU), shown above, is actually three
suits in one. These three may roughly be described
as: a union suit, a diver's suit, and a
suit of armor. Each is custom-tailored to an astronaut's
dimensions. Precise models of astronaut's
hands, for example, shown below, were
used to prepare fitted gloves.
The union suit is climbed into first. Made up
of a network of flexible tubes embedded in a
mesh fabric, this water-cooled underwear is
linked to the vital backpack portable life support
system (PLSS) where the water and oxygen are
stored and metered for precise circulation. The
cooling is necessary because body heat cannot
dissipate adequately.
Over this liquid cooling garment the Astronaut
wears the pressure garment assembly, a kind of
super-sophisticated diver's suit. Constructed of
rubbers and fabrics, and with cleverly contrived
joints, this assembly retains the oxygen atmosphere
without leakage while facilitating movement.
It too is linked into the PLSS, where carbon
dioxide and other contaminants are removed
from the oxygen stream. A chest-mounted remote
control unit permits the astronaut to adjust oxygen
flow and cooling temperature to match his
preferences. The PLSS will sustain activity for up
to 8 hours before its oxygen, water, and battery
power must be recharged. A separate oxygen
system, atop the PLSS, is available for emergencies;
up to 75 minutes' worth of oxygen is available,
depending on the draw-off rate.
Protecting the integrity of the pressure garment
is the outer suit of armor, a 13-layer composite
more like a coat of mail than the rigid
clanking uniform of castle-haunting ghosts. The
various layers of the outer garment protect the
knight of Apollo from the slings and arrows of
outer space: micrometeoroids, ultraviolet rays,
and other radiation. Visors and shades similarly
protect the eyes.
All suited up the astronaut is not unlike the
small boy who has been so bundled up that he
can hardly move, much less frolic in the snow.
Actually, given all the constraints and requirements,
spacesuit designers were highly successful
in affording the astronaut extensive mobility in
his EMU. Nevertheless, like the knights of old,
squires are needed to assist suited astronauts in
mounting their steeds and once aboard their
spacecraft the astronauts help each other in donning
and doffing their outfits. Going to the bathroom,
as one would imagine, would be nigh
impossible in such garb. So designers built in a
sheath urinal and collector bag. Aside from specially
absorbent underwear, there was no provision
for bowel movements during EVA. (Within
the spacecraft, these were coped with by sealable
disposable bags.)
A compressed food bar for the astronaut to
nibbie on is positioned inside the helmet, as is
a straw-like tube for sipping a beverage from a
neck-ring suspended bag. Close to the mouth also
are voice-actuated microphone pick-ups, which
are an integral part of a skull cap worn under
the helmet. A backpack-housed communications
system enables the astronaut out on the airless
Moon to converse with his colleagues in the
spacecraft and in Mission Control. The latter also
receive, through the PLSS, telemetered biomedical
data picked up from sensors on the astronaut.
Astronauts actually had a wardrobe of suits,
each oppropriately designed for use in training,
flight, surface and free-space EVA, and as backup.
Expensive, sartorial splendor was not one of
the suit's design criteria; survival plus the abilities
to communicate, move about, and deal with
equipment were.
