Scientific Uses of the Space Shuttle (1974) / Chapter Skim
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OPTICAL AND ULTRAVIOLET ASTRONOMY
OPTICAL AND ULTRAVIOLET ASTRONOMY
Pages 102-199
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From page 102... ...
They can particularly provide for high-resolution imaging, for spectroscopy without the intervening atmosphere of the earth, and for photometry and polarimetry with high spatial resolution. Broadly, the objectives are to investigate the dynamics, composition, and structure of planetary atmospheres and surfaces, of satellites and asteroids, and of comets.
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From page 103... ...
In some cases, these require the LST and a 1-m diffractionlimited Shuttle telescope; but a 0.5-m photometric telescope will sometimes suffice, and ultraviolet survey cameras will play important roles. Emphasis will be on the study of larger samples (thus on fainter objects)
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From page 104... ...
The mechanisms involved cannot be established until the grain composition is better known, and this in turn will probably require an understanding of how the grains are formed. The LST and the 1-m diffractionlimited Shuttle telescope will be the most valuable for pursuing these studies in the 1980's.
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From page 105... ...
Because of the large farultraviolet extinction, photographs with a Shuttle survey camera in this spectral region might delineate dust clouds better than is now possible. Ultraviolet observations of Lyman-a absorption have an important advantage over 21-cm-wavelength radio observations in mapping the local distribution of hydrogen, in that the geometry of the former is much better known than that of the latter.
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From page 106... ...
Space observations are essential to solving the riddles posed by galactic nuclei and quasars. The LST, a 1-m diffraction-limited Shuttle telescope, an ultraviolet survey camera on the Shuttle, and a very large light collector can each contribute in important ways to extending wavelength coverage, measuring the red shifts of fainter objects, resolving diameters and structures, and discovering fainter quasars.
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From page 107... ...
The distant ones require the LST, while the nearby ones require the field coverage of the deep-sky survey camera on the Shuttle. In addition, it will be very interesting to compare the stellar content of nearby galaxies with our galaxy.
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From page 108... ...
By providing the possibility of putting major telescopes in orbit, the Shuttle opens the exciting opportunity of reaching deeper into the realm of galaxies, galaxy clusters, and quasars to seek better answers to the scientifically and philosophically challenging questions of cosmology. In particular, one must search for distant clusters of galaxies with a 1-m deep-sky survey telescope reaching the 25th magnitude in selected sky samples, measure red shifts and magnitudes of cluster members by spectrophotometry with a large light collector, and measure luminosity profiles of cluster members with a diffraction-limited LST.
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From page 109... ...
The earth's atmosphere is partially obscuring at all wavelengths, but at some wavelengths it is so opaque as to block any penetration to the earth's surface. In the region of optical and ultraviolet astronomy, only a small fraction of the full wavelength range penetrates the atmosphere.
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From page 110... ...
In addition, it will allow the spatial resolution of known sources and the discovery of new sources. It will be a powerful complement to all other disciplines of space astronomy, from infrared through gamma rays.
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From page 111... ...
These functions would be served by a diffraction-limited //30 Cassegrain telescope of about 1-m aperture. The opportunity for utilizing photography and electronography arises because such materials will tolerate a space environment for the duration of a Shuttle flight (say, one month)
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From page 112... ...
C Small General-Purpose Telescope A useful astronomical instrument for the Shuttle sortie mode appears to be a modest, general-purpose uv telescope.
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From page 113... ...
Such a simple but versatile telescope, occupying so little space and payload might well become the most widely used astronomical instrument of the Shuttle sortie mode, flying as often as a dozen times a year as a noninterfering accompaniment of a wide variety of primary missions.
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From page 114... ...
Also, any large-scale evaluation of the distribution of galactic light is disturbed by interplanetary scattering from zodiacal light and gegenschein, which have angular sizes of the same order; it is thus essential to record galactic light and interplanetary scattering on the same field under the same conditions. The instrument required by these constraints must have a very wide field ( -- 60°)
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From page 115... ...
Guidance, control, and instrumentation might be copied with as few modifications as possible from those developed for the LST, at considerable savings in development cost. Two Shuttle flights should suffice to carry all parts of the system into orbit and to assemble it.
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From page 116... ...
Their cost per data bit is very low, yet the value of the discoveries and studies made with their aid may be equal to that of the most highly specific projects. Ultraviolet surveys using a meter-class all-reflecting Schmidt, reaching m = 19 or 20 photographically (fainter, if electronic cameras are available)
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From page 117... ...
If suitable electronographic cameras become available, each survey would need less than half of the number of days, while reaching more than a magnitude fainter; the programs could thus be accomplished on only four Shuttle flights with substantial cost savings even after including the expense of developing the electronographic camera (which would also have important uses in other parts of the space program)
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From page 118... ...
Although the sortie mode makes it more difficult to achieve the guidance requirements, it does allow manned participation in erecting the interferometer in space and in learning how to operate it. Further discussion of this topic will require a feasibility study.
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From page 119... ...
Scientific Uses of the Space Shuttle 119 .
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From page 120... ...
TECHNICAL IMPACT ON SHUTTLE A The Role of Man in Space-Shuttle Astronomy There can be four levels of manned interaction with optical-uv astronomical instruments carried to space by the Shuttle: active observation by the astronomer, operation of observing programs including film change, repair or maintenance of equipment including detector change, and assembly of instruments too large or too heavy for single-Shuttle flights.
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From page 121... ...
3. MAINTENANCE AND REPAIR Although the LSI will be a free-flying observatory, operated from the ground, its success will depend on revisits for service, maintenance, and refurbishment by the Space Shuttle.
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From page 122... ...
For a 1-m telescope operating at 5000 A, the resulting guidance error is less than 0.02 sec of arc rms. Imagery at shorter wavelengths would decrease the value to 0.01 sec of arc rms.
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From page 123... ...
Most other portions of the optical telescope assembly have passive thermal control. It would seem that the same basic thermal design would be satisfactory for the sortie mode.
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From page 124... ...
In some cases, a backup Shuttle control option may be useful. The data rates needed for the ground-based command and control functions are conventional and generally low; availability of an on-board computer is desirable and would be essential if the tracking and data-relay satellite should not be continuously available.
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From page 125... ...
It is for these reasons that we place primary emphasis on free-flyers, not only the LST but also smaller payloads. Even where the sortie mode is advantageous, to maximize the scientific return of the relatively small number of astronomy sortiemode flights, presented in the mission model, these flights should be extended beyond 7 days as soon as possible.
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From page 126... ...
SUMMARY AND RECOMMENDATIONS A Utilizing the Shuttle for Optical and Ultraviolet Space Astronomy Very-high-resolution images in visible and ultraviolet wavelengths will be required to answer many of the most vital questions concerning the nature of our solar system, the evolution of stars and galaxies, and the structure of the universe.
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From page 127... ...
seems preferable in the sortie mode, where frequent manned access is possible. Although it would be possible to conduct a photographic survey with a freeflying telescope that is visited about once per year, the difficulties of protecting against film fogging due to charged particles, against systematically overexposing or underexposing, against misfocusing, and against film jamming are sufficiently large to warrant use of alternate approaches if possible.
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From page 128... ...
We, therefore, recommend that a Tracking and Data Relay Satellite be available for astronomical space telescopes, particularly those utilizing the sortie mode. Optical and uv payloads are sensitive to contamination by the Shuttle.
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From page 129... ...
B Supporting Research and Technology The potential of the Shuttle for performing a large amount of space astronomy will not be borne out unless the proper telescopes and instruments are available when the Shuttle is ready to fly.
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From page 130... ...
In considering the scientific motivation, we have drawn heavily on the reports of the NASA Payload Planning Working Group (Blue Book) on Solar Physics and of the ESRO-PASOL Group and particularly on the discussions of those problems that they believe should consume a major fraction of the best efforts in solar physics through the first decade of the Shuttle era.
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From page 131... ...
Accelerated particles of comparatively low energy are observed to escape from the buildup area into interplanetary space. This, with many other aspects of the buildup, is not understood, and further observations of particle densities, fluxes, temperatures, and magnetic fields -- and the associated time variations -- are needed.
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From page 132... ...
Surprises, such as the recent realization that most of the solar wind originates in quite undistinguished regions of the corona, where the magnetic field is weak and open and the density is low, can be expected to be frequent and to lead to exciting revisions of our ideas on the structure of the outermost atmospheres of the sun and stars. Understanding these processes requires a complete specification of the density, temperature, and magnetic field in the corona and solar wind, with good temporal and spatial resolution, so that a full threedimensional model can be established.
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From page 133... ...
Scien tific Uses of the Space Shuttle 133 C Physical Problems of Broader Significance Solar activity originates below the visible levels of the solar atmosphere; our knowledge of the structure and dynamics of the interior is, at best, provisional.
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From page 134... ...
Similarly, the study of solar-active regions and the long-term interaction of the solar plasma and magnetic fields should increase our understanding of the coupling between solar convection, differential rotation, and the loss of angular momentum, as well as cycles of stellar activity. We can look to a continuing stimulation of many other areas in astrophysics coming from attempts to understand the complex questions posed by solar physics.
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From page 135... ...
Furthermore, the basic spacecraft, through Shuttle recovery, relaunch, and revisit, would provide a free-flying payload for long-duration solar experiments in the 1980's. Basic instrumentation for a Shuttle Sortie Solar Observatory (SSO)
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From page 136... ...
Particularly relevant are very-low-frequency radio measurements, in situ observations of solar-wind plasma and magnetic field, and high-energy particle measurements. Specific attention should be given to the scheduling of launches of such payloads to optimize the scientific returns coordinated with the solar Shuttle missions.
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From page 137... ...
Over a 10-year period, the total number of dedicated missions will be 34 including the following: Solar Telescope Cluster (STC) , 17 flights; Large Fine-Pointed Platform (LFPP)
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From page 138... ...
The total number of missions flying the SFPP only over 10 years is 24; the total number of flights of opportunity for the SFPP for the same period is 21. The sounding-rocket program goal of 25 flights per year would continue through 1982 at least; its continuation beyond that must be a subject for study over the coming few years as the Shuttle sortie capability becomes more defined.
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From page 139... ...
The SMM satellite concept developed by the Goddard Space Flight Center seems to provide an excellent basic capability that can support the pre-Shuttle SMM and that has the growth capability to accommodate instruments of the class of the Shuttle Sortie Observatory in a free-flying mode. The SMM concept envisages a Delta-launched satellite with the capability of fine pointing of some 500 kg of instruments at the sun.
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From page 140... ...
Two payloads have been identified as basic multiuse facilities: the Solar Telescope Cluster, which provides a basic set of optical feeds for a variety of imaging, spectroscopic, and polarization studies between 8 A and 10000 A; and a High-Energy Solar-Physics Package, which can carry out similar studies between 1 keV and 100 MeV and with the high time resolution necessary to study nonthermal events. We have also defined two different size fine-pointed platforms that can accommodate a variety of specialized instruments.
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From page 141... ...
(a) SOLAR TELESCOPE CLUSTER Since radiation emitted over the entire wavelength range from below 1 A into the millimetric range arises in different height and temperature regimes in the solar atmosphere, a battery of telescopes is required to carry out the needed research.
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From page 142... ...
The short-wavelength limit of this system is strictly set by the brightness of the source; for solar flare studies, this telescope should be usable down to approximately 2 A For imaging studies, the entire collecting area is available, and a spatial resolution of 1 sec of arc (or better)
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From page 143... ...
(c) GENERAL-PURPOSE, FINE-POINTED PLATFORMS Several scientific disciplines will require oriented platforms for the Shuttle sortie mode.
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From page 144... ...
As part of the Sortie Solar Observatory it would, for example, carry large special-purpose instruments not included in the Solar Telescope Cluster or a problem-oriented package of several experiments of a size intermediate between current rocket or OSOtype experiments. The design of these platforms must be such as to allow payload development with minimal interaction with the Shuttle itself.
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From page 145... ...
For example, a powerful method of determining density or temperature of the solar plasma makes use of the accurate measurement of ratios of spectral line intensities -- often at widely separated wavelengths -- and for this the absolute values of these intensities are essential. The Shuttle sortie mode is well suited for achieving accurate calibration since, in principle, instrument calibration can be monitored during operation and a thorough recalibration made immediately after flight.
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From page 146... ...
Reasonably high data rates would be required to operate the experiments from the ground. However, this capability would also permit returning all or a sampling of the data to earth in real-time or near real-time.
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From page 147... ...
We believe that a data-relay system permitting nearly continuous contact with the Shuttle sortie is essential for maximum scientific productivity. Further, we believe that the Orbiter/TDRS wideband data link, which in the present mission model is regarded as optional, is indispensable to the effective use of the sortie mode and should be a part of the Shuttle program from the beginning.
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From page 148... ...
G Use of the Payload Specialist Station Flights of the Solar Telescope Cluster and other major solar payloads will utilize, on occasion, the payload specialist in an interactive role in the experiment.
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From page 149... ...
We recommend that a panel of experienced Principal Investigators and satellite and experiment program managers from the various NASA Centers and from NASA Headquarters be established to examine the problem of quality assurance in the Shuttle era and to make specific recommendations on procedures for sortie instruments and for instrumentation on free-flyers. We believe that the basic quality assurance approach recommended in the Shuttle sortie model presented by NASA is an excellent one and recommend that Principal Investigators work closely with NASA to implement this approach.
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From page 150... ...
We, therefore, recommend that a flight program be initiated with the aim of development of a Shuttle Sortie Observatory consisting of (a) a solar telescope cluster of large collectors covering a wide range of the electromagnetic spectrum and designed to feed different focalplane instruments on different flights; (b)
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From page 151... ...
8. Because of the severe weight penalty presently imposed by the use of the sortie laboratory module, we recommend that, as a priority matter, adequate payload specialist console space be provided
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From page 152... ...
APPENDIX A 1. Representative Focal Plane Instrumentation for Use with the Solar Telescope Cluster0 Weight (kg)
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From page 153... ...
spectrograph, monitor instrumentation in support of Solar Telescope Cluster instruments (e.g., H-a heliograph x-ray spectrum monitor) , developmental instruments (e.g., xuv magnetograph)
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From page 154... ...
Having these attributes the pressurized laboratory concept constitutes a major advance in capability for definitive life-sciences investigations in space. In addition to biomedical investigations relevant to man's well-being in space, basic principles of biology and medicine can be examined using the 0-g environment as a research tool.
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From page 155... ...
Studies of the kinetics of cell growth and cell division in plant and animal tissue culture and in rapidly proliferating tissues in vivo (e.g., bone marrow, skin, intestinal epithelium) will be required to assess quantitative and qualitative effects of the space environment and 0 g on cell
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From page 156... ...
The Spacelab environment would not seem to offer any special opportunity for genetic studies other than those concerned with cell division and chromosome replication. The suggestion of synergism between radiation mutagenesis and weightlessness is probably neither a genetic nor a radiation problem but a problem in molecular or cellular reactions or both to 0 g.
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From page 157... ...
A variable-g centrifuge in the pressurized laboratory would strongly aid in this evaluation. Geotropic experiments should be performed only as part of experiments designed to examine other aspects of plant and cell
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From page 158... ...
For example, does the absence of gravity influence the morphogenesis of plant cells and affect chromosome replication to alter the mechanism of cell division? Previous flight studies have indicated that chromosomal aberrations do occur, and clinostat data suggest alteration of certain enzyme activity (glutamine synthetase)
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From page 159... ...
Results of complete life-cycle studies on small mammals such as mice and rats should provide important information, transferable to man in many cases, on physiological effects of weightlessness. A unique feature of the 0-g conditions in the pressurized laboratory will be the opportunity to determine in aqueous medium the morphogenic characteristics of some simple metazoans (hydra or perhaps copepods)
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From page 160... ...
IV. BIOMEDICINE The space environment offers new experimental approaches to analysis of mechanisms of a variety of fundamental physiological control systems.
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From page 161... ...
Experiments in both animals and humans will be needed to determine which parameters must be monitored inflight to detect functional changes in the cardiovascular control system and what procedures are effective in combating or preventing these changes. Examples of pertinent experiments that could be carried out in the pressurized laboratory are measurement of peripheral blood flow by venous occlusion plethysmograph during lower-body negative pressure (LBNP)
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From page 162... ...
As the atmosphere of the orbiter cabin and pressurized laboratory will be air at sea-level pressure (20% oxygen, 80% nitrogen at 760 mm Hg) , with the partial pressure of carbon dioxide maintained at less than 7 mm Hg, the basic composition of the gas that the crew and passengers will inspire presents no difficulty.
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From page 163... ...
The absence of gravitational force may reduce the total basal energy requirements of the body, which would produce a lower metabolic rate, or qualitatively altered metabolism, detectable for example as a decreased food intake or lower body temperature.
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From page 164... ...
The possibilities of mutation leading to new pathogens have been explored, and, although this must always be considered, the risks do not seem much greater than they would be on earth. It seems likely that alterations in host resistance attendant upon prolonged spaceflight and the spread of microorganisms within an enclosed space will be more important considerations.
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From page 165... ...
However, we must remain alert to this possibility. Preflight isolation of astronauts and immunization procedures have reduced almost to zero the incidence of inflight illnesses, and it is mandatory that precautions of this nature be continued in Shuttle flights.
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From page 166... ...
Regardless of what may be learned concerning sleep during Skylab missions, the question of mental state, i.e., alertness, and performance in relation to sleep, will not have been answered. The Shuttle flights provide an excellent opportunity to investigate this relationship.
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From page 167... ...
The molecular basis of 0-g perturbations of cell division * Radiobiological Advisory Panel, SSB Committee on Space Biology and Medicine, HZE-Particle Effects in Manned Space/light (National Academy of Sciences, Washington, D.C., 1973)
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From page 168... ...
All Shuttle flights should contain dosimetric devices and materials positioned to accumulate data on the flux and energy of the several radiations in space and the shielding effect of spacecraft components on their intensity and scattering. While the influence of these components on the actual radiation levels in different parts of the spacecraft can be predicted to some degree, it is necessary to test these expectations against observations.
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From page 169... ...
Forced convection and the use of capillary action in porous structures are presently utilized to minimize adverse 0-g effects on ionic and nonionic solute rejection, concentration gradients at the membrane surface, absorption phenomena, etc., in such devices as batteries and fuel cells designed for operation at 0 g. The orbiter cabin and pressurized laboratory should provide facilities for the testing of components of closed-loop life-support systems developed on the ground on a competing basis, so that efficient and reliable systems can be developed.
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From page 170... ...
Trace contaminants and particulate matter, including microorganisms, must be removed to levels consistent with standards recommended in reports of the NRC Committee on Toxicology* and the Space Science Board.f Recent developments in the computer sciences indicate that, by the 1980's, Shuttle users can expect that their needs for inflight *
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From page 171... ...
VIII. LABORATORY OPERATIONS The wide range of experimental approaches employed by the various biological and medical disciplines will require a pressurized laboratory module of the maximum size possible and with maximum flexibility as a major design principle.
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From page 172... ...
The first is that there can be no such thing as the ideal space laboratory for all biomedical work: there are too many different sets of equipments that will be needed at one time and not another. The design of the pressurized laboratory should therefore be based on modular concepts and interchangeable components.
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From page 173... ...
Adequate atmospheric and thermal control of the animal-holding facilities is essential. Ambient temperature should be held to about 72 ±2 °F and about 40 to 60% relative humidity for most mammals and birds.
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From page 174... ...
Many of the Shuttle flights will not have the pressurized laboratory or life scientists on board, so the types of measurements made would necessarily be relatively unsophisticated. For example, at this time there is an identifiable need for metabolic balance studies, requiring collection and preservation of urine and fecal samples.
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From page 175... ...
The reviews should be made at regular intervals, systematically, by formal panels appointed for fixed terms and consisting of members of the national and international scientific community. This procedure should be initiated promptly, because out of the current SR&T programs will doubtless come many of the Shuttle flight experiments.
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From page 176... ...
4. The composition of the atmosphere of the orbiter cabin and pressurized laboratory must be monitored continuously for oxygen and hydrogen and periodically for trace contaminants (e.g., CO, hydrocarbons, particularly ethylene, Freons, O3, sulfides, mercaptans, and amines)
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From page 177... ...
In addition to the Announcement of Flight Opportunities, there should be announcements in major relevant scientific publications. All proposals for flight experiments and SR&T should be subject to peer review by panels drawn from the international scientific community.
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From page 178... ...
14. If ESRO proceeds with the Space Laboratory, we strongly urge that life sciences be formally represented in the ESRO management structure.
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From page 179... ...
Planetary exploration has, however, only begun, and as long as there is a space program, planetary exploration should continue to be a major objective. Given television, remote operation, and sample return, unmanned operations have a significant capability to extend man's knowledge and experience throughout the solar system.
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From page 180... ...
In addition, capabilities for sample return and remote operation should be developed in parallel with the Shuttle in order to ensure that an effective program of planetary exploration will be available for use with this new capability. Some additions to the Shuttle capability will be necessary to ensure adequate escape energies for deep-space missions.
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From page 181... ...
The nature of the Space Shuttle creates a greater difference between deep-space exploration and orbital science than has existed up to now, and an effort is required to ensure that NASA's traditional and highly successful commitment to planetary exploration continues.
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From page 182... ...
planetary exploration program, and Martian exobiology may be a good first target. Finally, we may wish to turn attention to Titan when we are more familiar with the exploration of the outer planets.
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From page 183... ...
The analysis of lunar soil samples leads us to believe that solar activity has been relatively constant over the past million years; this severely constrains the hypothesis that the earth's glacial cycles, or ice ages, are related to changes in the sun's activity. Embedded in the lunar soil samples were found solar-wind atoms over 0.5 billion years old, atoms that appear to correspond to today's solar wind.
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From page 184... ...
IV. THE OUTER PLANETS The exploration of the outer planets -- Jupiter, Saturn, Uranus, and Neptune -- is of great interest for several reasons; the most fundamental is the importance of their overall composition and past history for the reconstruction of the radial, chemical, and thermal structures of the primeval solar nebula.
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From page 185... ...
Recently improved observations have led to improved models of the atmosphere of Uranus; but observations and theoretical understanding of Neptune are still in a rudimentary stage. Interest in the outer planets also focuses on several unique features of Jupiter and Saturn.
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From page 186... ...
The presence of the internal energy source is well established for Jupiter but not for Saturn, which presents an interesting dilemma in view of the usually assumed similarity of the two planets. The great variety of questions that need to be answered before the outer planets are reasonably well understood is reflected in the variety of quantitative and qualitative data that are required.
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From page 187... ...
The Saturn probe is in a sense a test for the new problem of entering the atmospheres of the outer planets.
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From page 188... ...
The next step in the exploration of Mars might be a roving vehicle on the surface of the planet or a sample return mission. It has been estimated that such missions might weigh some 2000 kg; since the energy requirements for Mars missions are fairly low, they also could be accomplished by a launch vehicle having the capability of a Shuttle/Centaur.
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From page 189... ...
Regardless of their composition, mineralogy, and structure, the samples will be exceedingly informative about the history, surface and internal processes, age, and degree of differentiation of the planet. Analogy with the lunar exploration program demonstrates the tremendous improvement in our understanding of the moon with the return of the first samples from the lunar surface (e.g., see "Proceedings of the Lunar Science Conferences," Geochim.
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From page 190... ...
Kick Stage (Burner II) , 1-m diameter, 2m long, 1400kg, $0.2 million.
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From page 191... ...
Some of them are indicated without and with a SEP stage, and mission 24 is shown in two variants that differ in the flight time, 800 versus 1100 days. It is clear that Centaur with a kick stage permits the launch of all but two missions to the outer planets, if the SEP is used.
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From page 193... ...
orbiter/lander 90 •• Tug recovered, one expe ocity at closest approach Mercury orbiter" 2 Venus lander 09 Pioneer Saturn probe 09 Mariner Jupiter orbiter 0 1 Pioneer Jupiter probe 04 Mariner Saturn orbiter 2 il X O 00 Encke rendezvous 02 Halley flyby 2 Asteroid rendezvous 06 -0 2 *
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From page 194... ...
capability is maintained, the necessary development and construction of the Tugs and SEP completed, and the problems of transporting them in the cargo bay of the Shuttle orbiter solved. It should be stressed that the list of planetary missions given in Table 19 is the minimum viable program of planetary exploration in the period 1979- 1990.
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From page 195... ...
auxiliary stage for the minimum planetary program; we further recommend a gradual development of Tugs and of other more advanced propulsion methods for a full program of planetary explorations.
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From page 196... ...
In orbit, which is typically 100-200nm, the payload bay doors open to expose the payload to the space environment. Upon completion of the mission, the orbiter bay doors are closed and the spacecraft is deorbited with the orbiter performing cross-range maneuvers and aerodynamic flight resulting in a horizontal landing at a landing strip.
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From page 197... ...
From the Eastern Test Range (ETR) 65,000 Ib could be delivered to a 210-naut mi circular orbit at 28.5-deg inclination using the basic Shuttle propulsion.
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