You should probably read the heat transfer
primer page first.
It gets up to 280 F (138
C) on the moon.
At high noon the average temperature of the lunar surface
can reach that temperature. But that's not the same thing as saying
it was 72 F (22 C) in Los Angeles today. The latter is air
temperature. The temperature of various surfaces in Los
Angeles might have been as high as 180 F (82 C). Air temperature has
no meaning on the moon because there's no air.
280 F (138 C) may be the temperature of the lunar surface material
at equilibrium in full sunlight, but it's not the temperature of any
random object in a similar situation. Objects will be heated to that
temperature only if they absorb the same amount of sunlight as lunar
surface material, and also radiate it at the same rate. More
reflective objects absorb less light and are heated less. Less
reflective items may be heated even hotter.
Just as on earth, the temperatures at morning and evening on the
moon are lower than at noon. This is because the sun strikes the
surface at a more acute angle and therefore isn't as intense. The
lunar landing sites and times were chosen so that the astronauts would
be working there in the early morning before the temperature had risen
to its hottest. This reduced the surface temperature at those sites.
Air temperature is not the same thing as surface temperature.
The physics term for this phenomenon is "form factor for radiative
heat transfer". Quite a mouthful. The meteorological term is "angle
of insolation" and it's why we have seasons on earth.
Photographic film melts
at 150 F (65 C). Therefore you can't use it to take photos on the
This would be a problem only if there was a way for the film to be
heated. Since the film wasn't in direct sunlight it wouldn't have
The only source of heat would have been conductive heat transfer
through the camera body, and only at the points where the film
physically touched the body or a connected part. Rolled up on its
spool inside the magazine it was relatively safe from conducted heat.
Hasselblad gave the lunar surface cameras a shiny polished metal
finish to reduce the amount of light they would absorb.
David Groves, PhD, has
shown that the extreme heat of the lunar environment would alter the
colors in the film used to take the Apollo pictures. [Bennett and
Percy, Dark Moon, p. 540]
Dr. Groves' study is seriously flawed.
First, Dr. Groves assumes that when NASA says the lunar surface
temperature at the Apollo landing sites varies from 180 F in the sun
to -180 F in the shade, this means the Hasselblad cameras and film
also reached this temperature. In fact, the temperature of the lunar
surface (i.e., rocks and dust) as quoted by NASA has nothing to do
with the equilibrium temperature reached by other objects exposed to
sunlight in the lunar environment. Since the film magazine was
covered with polished aluminum it would have absorbed very little
radiant energy from the sun. Further, Hasselblad confirms that
additional shield plates were added to the Apollo magazines to enhance
their thermal insulative properties.
Second, Dr. Groves assumes that the film was subject to constant
extreme heat for an average of four hours, corresponding to the
average duration of a lunar EVA. Since the only possible method of
heating would be absorption from sunlight, this would require the
astronauts to stand facing the sun continuously for four hours. But
of course that's not what they did. They were quite active,
alternating between sunlight and shadow, turning toward and away from
the sun constantly.
Now a cold object placed in the sunlight will begin to warm. It
will not immediately leap to its hottest temperature. Similarly, a
hot object removed from sunlight will radiate away its heat and become
cool again. It can take quite a while for objects to reach these
various equilibrium temperatures. The magazine alternated between
sunlight and shade while it was attached to the camera, and was stored
away from sunlight when not attached. It is highly unlikely the
magazine ever reached either extreme of its temperature band, which is
not the 180 F to -180 F range quoted for the lunar rocks and dust.
And the film itself was never in direct sunlight and so would have
absorbed absolutely no radiant energy.
Third, Dr. Groves uses an oven to heat the film. This is
completely absurd. An oven uses primarily convective heat transfer:
the element heats the air in the oven, and the air then transfers the
heat to the material being cooked. But because there is no air on the
moon, there is no such convective heat transfer. Dr. Groves has
chosen the only mode of heat transfer which doesn't occur on
Attempting to simulate the thermal conditions of the lunar
environment, Dr. Groves uses the only mode of heat transfer
not pertinent to space.
Without a fluid medium to convectively transfer any heat from the
magazine to the film itself, only two modes of heat transfer are
possible: radiant transfer from the inner surface of the magazine to
the film itself (the amount of which would be small in this
scenario), and conductive transfer from the magazine case through the
winding mechanism to the film itself. This is a very limited path of
In any case, Dr. Groves' baking the film in an oven at 180 F for
four hours is largely unrepresentative of the conditions in which the
Apollo photographic film was used and stored. It is baffling to see
such unsophisticated and flawed analysis issued under the guise of
professional science. We struggle to understand how even the most
basic principles of thermodynamics seem to find no place in
Dr. Groves' study.
If film gets too cold it
will crack and the emulsion will flake off. The bitter cold of space
would ruin the film.
We can point out that conspiracy theorists can't agree on whether
the film is subjected to intense heat or intense cold in space. But
to answer the question directly we point out that the Apollo film was
manufactured with Kodak's Estar base. This base is an extra-thin
polyester (not celluloid) material formulated for high-altitude (i.e.,
cold temperature) aerial photography, especially photoreconaissance.
The magazine casings were coated with aluminum. While this would
reflect away most of the light, it would absorb enough to keep the
film within its operating temperature.