Utility ot Manned Space Operations
tor Photogrammetry and tor
a Physics Laboratory in Space
PAUL ROSENBERG,
Director oj Research, Paul Rosenberg Associates,
Consulting Physicists, Mount Vernon, New York
preceding speakers on this panel have
T expressed
the opinion that unmanned inHE
strumented space vehicles can make observa~
tions and perform experiments almost as well
as manned space vehicles. I share this viewpoint, which will be borne out later in this
paper when the usefulness of a manned
physics laboratory in space is considered and
when photogrammetry from space vehicles
is discussed.
This does not mean to say, however, that
manned space vehicles are unnecessary. On
the contrary, I believe firmly that the capability of l'nanned space operations should be,
and will be, exploited to its fullest for at least
two reasons:
(1) Instruments cannot entirely replace
man's resourcefulness, his discrimination as an observer, and his ability to
take advantage of new, unpredictable
sti tuations as they arise.
(2) Man's spirit of adventure will inevitably drive him to manned space operations and to personal space exploration, regardless of the effectiveness of
unmanned instrumen ted space vehicles.
A manned space vehicle would be an interesting place in which to set up an otherwise conventional physics research laboratory. Compared to a physics laboratory on
the Earth's surface, the advantages of a
space physics laboratory would be: apparent
weightlessness; absence of the earth's magnetic field; availability of an unlimited
amount of high vacuum; availability of high
energy cosmic radiations and particles. Let
us consider each of these potential advantages
in turn.
Weightlessness might seem to be a boon to
laboratory experimenters who often wish
they could use the proverbial "sky hook" in
designing apparatus. On the other hand, the
experimenter in a weightless space laboratory
would have to forego the many inestimable
conveniences of gravity that he enjoys in
his conventional Earth-bound laboratory.
For example, he could no longer rest a tripod
support on a work bench in the space laboratory with confidence that the tripod and
the equipment it supports will remain securely in place. The mere task of rinsing a
beaker or washing a test tube becomes awkward in the weightless condition of a freely
orbiting space laboratory. All told, weightlessness would probably be more of a handicap than an advantage in general laboratory
work.
The weightlessness of a manned space
vehicle might be useful for the preparation of
alloys and the purification of metals at high
temperatures without contamination from
contact with the walls of the containing vessel. On the other hand, this same effect has
been accomplished in terrestrial laboratories
by electromagnetic fields which suspend
molten masses of alloy away from the sides
and bottom of a crucible (at less cost than
the cost of building and launching a manned
space laboratory).
The absence of the Earth's magnetic field
in a space vehicle is a relatively trivial advantage, even for experiments that might require zero magnetic field. For one thing, it is
EDITOR'S N OTE.-By permission graciously given by the author and publisher this paper is reprinted from Vistas in Astronautics, Vol. II, pages 154-157 (New York, Pergamon Press, Inc., 1959).
The paper was presented at the Second Annual AFOSR Astronautics Symposium, 28-30 April 1958,
Denver, Colorado, co-sponsored by the Air Force Office of Scientific Research and the Institute of the
Aeronautical Sciences. The author, Dr. Paul Rosenberg, was the concluding speaker on a panel composed
of: Col. Paul A. Campbell, USAF (Chairman); Dean Athelstan F. Spilhalls, Institllte of Technology,
University of Minnesota; Professor Fred L. Whipple, Director, Smithsonian Astrophysical Observatory,
Harvard University; Professor H. J. Stewart, Jet Propulsion Laboratory, California Institute of Technology; Dr. William H. Pickering, Director, Jet Propulsion Laboratory, California Institute of Technology; and Professor George Gamou, University of Colorado.
455
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PHOTOGRAMMETRIC ENGINEERING
possible to shield or neutralize the Earth's
magnetic field adequately in a terrestrial
laboratory. For another, a manned space
laboratory is likely to have magnetic fields
produced by its own materials and equipment, unless the entire space vehicle is
specially constructed for magnetic-field-free
experimen ts.
A quarter-century ago when physicists
struggled to obtain and maintain high vacuum for laboratory experiments, they wished
wistfully that the vacuum of outer space were
at their disposal. This wish can come true in
a space laboratory. An experimental chamber
could be completely evacuated simply by
opening a stopcock, so to speak, between the
chamber and the exterior of the space laboratory. However, conventional vacuum
techniques are now developed to the point
where they are adequate for most laboratory
experiments requiring high vacuum. Only a
few experiments are likely to require the
higher vacuum of space. (Incidental1y, the
manned space laboratory would have to carry
a supply of expendable air to permit repeated evacuation of an experimental chamber by connection to the space outside.)
A far more important use of the weightless
condition of a manned space laboratory
would be to conduct experiments to measure
the gravitational red shift, e.g. by nuclear
magnetic resonance. However, it is almost
equal1y feasible to perform these experiments
by means of instrumented, unmanned space
vehicles.
The availability of high energy cosmic
radiations and particles in space is perhaps
the most important advantage that a manned
physics laboratory in space would have as
compared with a terrestrial laboratory.
Nevertheless, experiments with these radiations and particles, like the gravitational red
shift experiments, can be performed also by
un manned instrumen ted space vehicles.
When manned space operation becomes
readily available, it wil1 be wel1 worth while
to set up and try a manned physics laboratory in space. Nevertheless it must be concluded, albeit reluctantly, that the advantages of a manned physics laboratory in
space do not, by themselves, justify manned
space operation.
Let us now consider the applications of
manned and unmanned space operations to
photogrammetry (which is the process of
mapping the Earth's surface and measuring
relief accurately by aerial photography).
Photogrammetry is a highly developed
branch of engineering, so much so that only
a fraction of the Earth's surface is adequately
mapped by professional photogrammetric
standards. Earth satel1ites or other space
vehicles, fitted with photogrammetric equipment, might assist and accelerate conventional world-wide photogrammetric mappll1g.
The chief advantage of an orbiting Earth
satel1ite for photogrammetry is the vehicle's
high altitude. This will enable large areas of
the Earth's surface to be photographed on
one negative. For example, a conventional
aerial camera in an Earth satel1ite at an altitude of 1,600 miles, the approximate
apogee altitude of 1958 Alpha (Explorer I),
can photograph more than one-third the area
of the entire earth in a single exposure, using
a lens with a 90° field of view. Wide coverage
photographs such as these should be useful
for geodetic purposes, to tie-in large scale
maps made by other means.
However, a conventional aerial camera
operated at satel1ite altitudes has the inher~rit
disadvantage that the scale of the photograph is small. Cameras of very ~long focal
length (e.g. 100 or 200 ft.) must be used in
satel1ites to give useful1y large scales. These
"VLFLI" ("very long focal length indeed")
cameras are feasible in space vehicles because the camera is effectively weightless
when the satellite is in free orbit. This al10ws
the two ends of the camera (lens and film
holder) to be supported with respect to each
other by relatively light connecting members
of great length. The camera can extend far
outside the satel1ite proper while orbiting
because the aerodynamic drag wil1 be negligible at these altitudes. The camera can
fold into the satel1ite for launching, and unfold automatically to ful1 length outside the
satellite after it is in orbit.
The long focal length satellite camera will
need a lens of large diameter (e.g. 100 in.) in
order to obtain a useful1y low f-number. This
lens could also be used in the telescope of a
manned astronomical observatory in the
same satel1ite.
An important disadvantage of aerial photographs made with long focal length satel1ite
cameras is that the so-cal1ed base-height ratio
is small. This is the photogrammetrist's way
of saying that the stereo-angle in the stereomodel is too smal1 for accurate measurement
of relief or contours. Aerial negatives of
unwieldy size, such as 20 X 20 ft. would have
to be exposed in these cameras to give useful
base-height ratios. It would be awkward, to
say the least, to have to change rapidly from
one such negative frame to the next, to say
457
SPACE OPERATIONS
nothing of the problem of shielding this
large film from the intense cosmic- and solar
radiations that will doubtlessly be encountered at satellite altitudes. Furthermore, the
film emulsion must be unaffected by the
vacuum and temperature extremes of space;
(conven tional em ulsions would be affected
adversely).
Photogrammetric cameras in satellite vehicles present additional problems* which will
only be mentioned here: stabilization; determination of the Earth's vertical; image
motion compensation.
Return of the exposed photographic film
to the ground is the most complete and accurate method for recovering the photogrammetric information. This is obviously possible
if a capability for manned space operation is
assumed, because the vehicle and its occupants must be returned safely to Earth. However, it is also true that the film could be
developed automatically in an unmanned
space vehicle, and the photographic information transmitted to the ground by radio
facsimile. Consequently a capability for
manned space operations is not necessary for
photogrammetry from space vehicles.
The operation and orientation of the
camera in the unmanned vehicle will have to
be completely automatic. Operation in a
manned vehicle will be simpler because the
vehicle's occupant (or occupants) can control
and monitor the camera. However, the normal motions of the operator's arms, legs and
body will give the vehicle erratic angular rotations which will disturb the stabilization
and orien tation of the camera, especially if
the space vehicle is small in size and mass.
Indeed, changes in the rate of circulation of
blood in an occupant of an orbiting space
vehicle (caused by exertion or emotional
stress, for example) can produce undesired
angular accelerations of the vehicle because
of the conservation of angular momentum.
Television cameras can obviously be carried
by Earth satellites and space vehicles,
manned and unmanned. These TV cameras
are potentially valuable instruments for
meteorologic studies and weather forecasting.
However, special TV cameras will have to be
developed for accurate topographic mapping
(relief mapping) which demands high ground
resolution and wide angle coverage simultaneously. Currently available commercial
television cameras are able to give either high
ground resolution with small angle coverage,
or large angle coverage with poor ground
resolution.
The first explorations of the Moon, the
planets and their moons will doubtlessly be
made by photogrammetry and aerial reconnaissance. Terrestrial photogrammetry from
manned and unmanned Earth satellites,
whether by photography, television or other
electronic methods, will therefore be but a
prelude to the more fascinating applications
of these techniques to lunar and planetary
exploration. t
* Earth Satellite Photogrammetry, Pau! Rosen-
t This paper was followed by a discussion between panel members. Dr. Rosenberg, because of
convincing reasons, recommended the omission of
the discussion.
berg, PHOTOGRAMMETRIC
XXIV, No.3, June, 1958.
ENGINEERING,
Vol.
The IsopachometerA New Type Parallax Bar*
ROBER T
J. HACKMAN,
U. S. Geological Survey,
Washington, D. C.
(Abstract is on next page)
INTRODUCTION
isopachometer was developed by the
U. S. Geological Survey as an aid to
photogeologic interpretation from paper
prints. It was designed primarily to permit
T
HE
two floating dots, that can be set to represent
any predetermined vertical interval, to be
moved about within the stereoscopic model of
two vertical aerial photographs. The instrument is especially applicable in geologic map-
* Publication authorized by the Director, U. S. Geological Survey.