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At least 811 records · Page 45
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

The Deep Space Network: A Radio Communications Instrument for Deep Space Exploration

The primary purpose of the Deep Space Network (DSN) is to serve as a communications instrument for deep space exploration, providing communications between the spacecraft and the ground facilities. The uplink communications channel provides instructions or commands to the spacecraft. The downlink communications channel provides command verification and spacecraft engineering and science instrument payload data.

Renzetti, N. A.↗
NASA NTRS1982

Studies of beam plasma interactions in a space simulation chamber using prototype Space Shuttle instruments

In March, 1981, electron beam experiments were conducted in a large space simulation chamber using equipment destined to be flown aboard NASA's Office of Space Science-1 pallet (OSS-1). Two major flight experiments were involved. They include the Vehicle Charging and Potential (VCAP) experiment and the Plasma Diagnostics Package (PDP). Apparatus connected with VCAP included a Fast Pulse Electron Gun (FPEG), and a Charge and Current Probe (CCP). A preliminary view is provided of the results obtained when the electron emissions were held steady over relatively long periods of time such that steady state conditions could be obtained with respect to the electron beam interaction with the neutral gases and plasma of the vacuum chamber. Of particular interest was the plasma instability feature known as the Beam Plasma Discharge. For the present experiments the FPEG was used in a dc mode with a range of currents of 2 to 80 mA at a beam energy of 970 eV. Attention is given to the emissions of VLF and HF noise associated with the dc beam.

Banks, P. M.↗
NASA NTRS1984

Space exposure of composite materials for large space structures (A0134)

The objective of this experiment is to evaluate the effects of the near-Earth orbital environment on the physical and chemical properties of laminated continuous-filament composites and composites resin films for use in large space structures and advanced spacecraft. The experiment is passive and occupies about one-half of a 6-in.-deep peripheral tray. Specimens of composite materials and polymeric and resin films are arranged above and below the experiment mounting plate to enable both exposure and nonexposure to sunlight. This provides a comparison of the effects of ultraviolet plus vacuum plus thermal cycling and those of vacuum plus thermal cycling on these materials. The experiment tray is thermally isolated from the Long Duration Exposure Facility structure to allow the material specimens to experience a wide range of thermal cycles. Tensile and compression specimens will be used to evaluate the laminated composite materials. A number of the specimens are precut and ready for testing after space exposure, whereas other specimens will be prepared from larger samples.

Wayne S Slemp↗
NASA NTRS1984

Observations of the Earth's magnetic field from the Space Station: Measurement at high and extremely low altitude using Space Station-controlled free-flyers

Simulation studies established that the main (core), crustal and electrojet components of the Earth's magnetic field can be observed with greater resolution or over a longer time-base than is presently possible by using the capabilities provided by the space station. Two systems are studied. The first, a large lifetime, magnetic monitor would observe the main field and its time variation. The second, a remotely-piloted, magnetic probe would observe the crustal field at low altitude and the electrojet field in situ. The system design and the scientific performance of these systems is assessed. The advantages of the space station are reviewed.

Webster, W., Jr.↗
NASA NTRS1983

Space station needs, attributes, and architectural options: Space station program cost analysis

This report documents the principal cost results (Task 3) derived from the Space Station Needs, Attributes, and Architectural Options study conducted for NASA by the McDonnell Douglas Astronautics Company. The determined costs were those of Architectural Options (Task 2) defined to satisfy Mission Requirements (Task 1) developed within the study. A major feature of this part of the study was the consideration of realistic NASA budget constraints on the recommended architecture. Thus, the space station funding requirements were adjusted by altering schedules until they were consistent with current NASA budget trends.

Cowls, R. S.↗
NASA NTRS1984

Concepts used in the preparation of the document - Space and planetary environment criteria guidelines for use in space vehicle development 1982 revision

The NASA/Marshall Space Flight Center has developed a series of documents concerning space and planetary environments for use in the formulation of aerospace vehicle and spacecraft design criteria. For the earth above 90km altitude, and for the moon, planets, and other bodies in the Solar System; information is provided in disciplinary area of importance to the spacecraft designer such as planetary geology and morphology, atmospheric and ionospheric structures, radiation, particles, geomagnetic fields, astrodynamic constants, and meteoroids. This paper presents the philosophy used in the preparation of the current (1982) version of the document. Specific topics will be discussed in relation to their significance for aerospace vehicle and spacecraft development and mission analysis.

Davis, M. H.↗
NASA NTRS1983

Space Shuttle, private enterprise and intellectual properties in the context of space manufacturing

It is a national policy to make the capabilities of the Space Transportat ion System available to a wide range of potential users. This includes its availability as a space manufacturing facility for commercial activities, which may be carried out on a reimbursable basis or as a joint endeavor with NASA, but with substantial private investment. In any high risk, long lead-time research and development activity directed towards commercialization, the protection afforded the results of the research and development under the laws relating to intellectual property rights may provide an important incentive for private investment. The paper reviews NASA's policies and practices for the protection of privately-established intellectual property rights involved in STS use, with particular emphasis on reimbursable launch agreements and joint endeavor agreements.

Hosenball, S. N.↗
NASA NTRS1984

Space adaptation syndrome: Incidence and operational implications for the space transportation system program

Better methods for the prediction, prevention, and treatment of the space adaptation syndome (SAS) were developed. A systematic, long range program of operationally oriented data collection on all individuals flying space shuttle missions was initiated. Preflight activities include the use of a motion experience questionnaire, laboratory tests of susceptibility to motion sickness induced by Coriolis stimuli and determinations of antimotion sickness drug efficacy and side effects. During flight, each crewmember is required to provide a daily report of symptom status, use of medications, and other vestibular related sensations. Additional data are obtained postflight. During the first nine shuttle missions, the reported incidence of SAS has been48%. Self-induced head motions and unusual visual orientation attitudes appear to be the principal triggering stimuli. Antimotion sickness medication, was of limited therapeutic value. Complete recovery from symptoms occurred by mission day three or four. Also of relevance is the lack of a statistically significant correlation between the ground based Coriolis test and SAS. The episodes of SAS have resulted in no impact to shuttle mission objectives and, no significant impact to mission timelines.

Homick, J. L.↗
NASA NTRS1985

Space Station crew safety alternatives study. Volume 5: Space Station safety plan

The Space Station Safety Plan has been prepared as an adjunct to the subject contract final report, suggesting the tasks and implementation procedures to ensure that threats are addressed and resolution strategy options identified and incorporated into the space station program. The safety program's approach is to realize minimum risk exposure without levying undue design and operational constraints. Safety objectives and risk acceptances are discussed.

Mead, G. H.↗
NASA NTRS1985

Space research in the era of the space station

The major elements of the NASA manned space station are described, and science activities it could be used for are suggested. The core facilities include at least two major laboratory modules with supporting utilities, including habitation accommodations, docking facilities, power and heat rejection units, and external space and support for attached payloads. A vertically oriented structure, called the Power Tower, is being studied. Scientific accommodations inside the modules include major facility instrumentation for a variety of microgravity research projects, with initial emphasis upon materials research and life sciences. The second element is composed of free-flying satellites operating in orbits near the core station. The third element consists of satellites in polar orbits. One or more large, multi-instrument platforms are planned for Earth observation and solar-terrestrial processes research.

Banks, P. M.↗
NASA NTRS1984

Static shape determination and control for large space structures. I - The flexible beam. II - A large space antenna

A method for determining and controlling the shape of large, continuous space structures by means of discrete or pointwise observations and control devices is presented. The general linear boundary value problem satisfied by a one-dimensional shape function is defined, and the existence of solutions is studied. The static shape control problems for one-dimensional systems with and without rigid body modes and the static shape estimation problem are presented and solved. Eigenfunction expansions are presented which provide approximations to the algorithm terms when the associated Green's function is not known. An integral operator approach is applied to the multidimensional static problem, and the results are illustrated with a finite element model of the disk of a large space antenna which assumes no rigid body modes. It is shown that the shape control algorithm must be modified for systems with rigid body modes.

Weeks, C. J.↗
NASA NTRS1985

Space plasma simulations; Proceedings of the Second International School for Space Simulations, Kapaa, HI, February 4-15, 1985. Parts 1 & 2

Space plasma simulations, observations, and theories are discussed. Papers are presented on the capabilities of various types of simulation codes and simulation models. Consideration is given to plasma waves in the earth's magnetotail, outer planet magnetosphere, geospace, and the auroral and polar cap regions. Topics discussed include space plasma turbulent dissipation, the kinetics of plasma waves, wave-particle interactions, whistler mode propagation, global energy regulation, and auroral arc formation.

Ashour-Abdalla, M.↗
NASA NTRS1987

Impact verification of space suit design for space station

The ballistic limits of single sheet and double sheet structures made of 6061 T6 Aluminum of 1.8 mm and larger nominal thickness were investigated for projectiles of 1.5 mm diameter fired in the Vertical Gun Range Test Facility and NASA Ames Research Center. The hole diameters and sheet deformation behavior were studied for various ratios of sheet spacing to projectile diameter. The results indicate that for projectiles of less than 1.5 mm diameter the ballistic limit exceeds the nominal 10 km/sec orbital debris encounter velocity, if a single-sheet suit of 1.8 mm thickness is behind a single bumper sheet of 1 mm thickness spaced 12.5 mm apart.

Fish, Richard H.↗
NASA NTRS1986

Space Station - A model for future cooperation in space

Advances in the ability to operate in, and thus to exploit, space have come more rapidly than almost anything else that has been done. From the beginning, nations have engaged in both cooperation and competition, from the stage of adventurous exploration to the current routine commercial activity. The Space Station program serves as a focus for the free world to move forward together, sharing both risks and benefits during the initial, formative period of an entirely new level of capability.

Raney, W. P.↗
NASA NTRS1986

System level verification applying the Space Shuttle experience to the Space Station

The applicability of the verification process for the Shuttle guidance, navigation and control (GNC) and data management system (DMS) for the development of the Space Station are described. Shuttle avionics hardware/software integration was delayed to finalize the hardware design before detailed definition and testing of the software. A block diagram is provided of the flight simulation laboratory used to test the GNC programs before flight data were available. The Station will have distributed computers, unlike the Orbiter, and will only be assembled fully in space. Standardized integration simulation test equipment are being defined to guide the development of hardware and software. The simulation capability may become part of nominal in-flight operations to initiate new capabilities as they are added to the Station. The Station GNC and DMS systems development will be somewhat simplified relative to those of the Shuttle because ascent and reentry will not be considered for the Station.

Gilbert, David W.↗
NASA NTRS1987

Space charge effects during the injection of dense electron beams into space plasmas

One-dimensional electrostatic particle simulations are used to investigate the injection and propagation of intense electron beams and the plasma response to the beam injection. Beam densities greater than about the plasma density are considered. It is shown that if the injection is continuous, most of the beam electrons are drawn back into the spacecraft because of the buildup of positive charge on the spacecraft. Those electrons which are able to propagate away from the spacecraft are emitted periodically because of space charge oscillations induced by electric fields associated with the beam. A substantial increase in the fraction and average energy of electrons which can propagate away can be obtained if the injection is changed to periodic pulses having width and period matched to the induced space charge oscillations.

Winglee, R. M.↗