FIRST STEPS TOWARD SPACE - Smithsonian Institution Libraries

NUMBER 10 211
FIGURE 2.—Principal features of the Coelostat.
with the extra advantage that stability at launch
from Earth and during flight would be improved.
Only at lunar touchdown, when spin must be
annulled, need a condition of zero gravity exist
momentarily. It was obvious that spin could either
be annulled during observations, or television used.
But cessation of spin, even for short periods, would
be a retrograde step to be avoided if possible, while
viewing by television entailed heavy gear and would
in any case, unless much refined, be incapable of
showing stars. However a neat solution was provided
by Edwards in the form of a light and simple
optical device which in essence is a slow-motion
stroboscope. Briefly, the "Coelostat," as it was
named (see Figure 2), consisted of two mirrors (A
and B) placed at 90° to each other and revolving
together. Two more mirrors (C and D) formed a
stationary periscope into which the observer looked.
Light falling on mirror B from the scene was reflected
on to A, C, and D in turn and then passed
via a suitable eyepiece to the eye of the observer.
When the mirror-pair A/B was revolved at half the
speed at which the ship was rotating the exterior
scene would appear stationary to an observer. A
FIGURE 3.—Mock-up of the Coelostat as demonstrated at the
Science Museum, London.
working model of this instrument is shown in
Figure 3. Probably the first ever produced solely
for use in a spaceship, it was made by Smith, 12 and
was demonstrated, immobilizing a rotating disc, at
a meeting of the Society held in the Science Museum,
South Kensington, London, on 7 March 1939.
Another type of coelostat for radial viewing was
discussed but not developed.
We may now pass on to examine the "Moonship"
evolved by the Technical Committee and
integrated by R. A. Smith, whose drawings are
reproduced in Figure 4. In the drawings each of six
main "Steps" consisted of a hexagonal honeycomb
formation of individually complete solid propellant
rockets. This novel constructional approach originated
with Edwards, who maintained that solid
systems competing with liquid complexes could be
developed, and who in any case was disposed to
inventive heterodoxy. Certainly, solid units, lacking
complicated pumps, valves and plumbing, were far
simpler and more compact affairs than liquid propellant
systems. Moreover, with the proposed cellular
construction it would be possible to keep dead
weight at a minimum by jettisoning used units
piecemeal instead of as whole steps, with a consequently
much improved overall performance. It
will also be apparent that the thrust would be
controllable simply by regulating the frequency at
which units are ignited. Indeed, this battery system
seems to have been the first practical scheme for
controlling the thrust of large solid propellant
rockets. The design also differed from all its contemporaries,
and presaged modern practice, in be-