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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Radiation effects during space flights are discussed in the context of the sources and dangers of such radiation and the radiobiological prerequisites for establishing safe levels of radiation dosage. Standard safe levels of radiation during space flight are established.
Improvements in the landing system of the Soyuz spacecraft are discussed. The system of parachutes is designed to guarantee a safe landing. The design attempts to cover all possible emergency situations. Selection of the landing area and time of ejection is an important aspect of safe descent.
The engineering and safety techniques used to assure the reliable and safe operation of large wind turbine generators utilizing the Mod 2 Wind Turbine System Program as an example is described. The techniques involve a careful definition of the wind turbine's natural and operating environments, use of proven structural design criteria and analysis techniques, an evaluation of potential failure modes and hazards, and use of a fail safe and redundant component engineering philosophy. The role of an effective quality assurance program, tailored to specific hardware criticality, and the checkout and validation program developed to assure system integrity are described.
The performance characteristics of the transmitter experiment package (TEP) aboard the Communications Technology Satellite (CTS) measured during its first 2 years in orbit are presented. The TEP consists of a nominal 200 watt output stage tube (OST), a supporting power processing system (PPS), and a variable conductance heat pipe system (VCHPS). The OST, a traveling wave tube augmented with a 10 stage depressed collector has an overall saturated average efficiency of 51.5 percent and an average saturated radio frequency (rf) output power at center band frequency of 240 watts. The PPS operated with a measured efficiency of 86.5 to 88.5 percent. The VCHPS, using three pipes to conduct heat from the PPS and the OST to a 52 by 124 centimeter radiator fin, maintained the PPS baseplate temperature below 50 C for all operating conditions. The TEP performance characteristics presented include frequency response, rf output power, thermal performance, and efficiency. Communications characteristics were evaluated by using both video and audio modulated signals. On four occasions, the TEP experienced temporary thermal control system malfunctions. The anomalies were terminated safely, and the problem was investigated because of the potential for TEP damage due to the signficant temperature increases. Safe TEP operating procedures were established.
This paper describes the design of the Modular Attitude Control Subsystem (MACS) that is incorporated in the NASA Multimission Modular Spacecraft (MMS). The MACS is required to provide precision attitude control for a wide class of spacecraft missions including earth pointing, stellar pointing and solar pointing. The MACS is composed of sensors, actuators and associated electronics. Normally the MACS computational, logic and sequencing functions are performed by an Onboard Computer (OBC) located in the MMS; however, the MACS implements an independent backup safe hold attitude controller to protect against the consequences of an OBC failure. The contents of the paper include a description of the MACS configuration and functional operation. The MACS operational modes and performance requirements are described followed by a discussion of the MACS component characteristics. The paper concludes with a description of the safe hold controller design and typical MACS OBC algorithms.
Training manual used for preflight conditioning of NASA astronauts is written for audience with diverse backgrounds and interests. It suggests programs for various levels of fitness, including sample starter programs, safe progression schedules, and stretching exercises. Related information on equipment needs, environmental coonsiderations, and precautions can help readers design safe and effective running programs.
A method and apparatus is described for safely reducing abnormally high intraocular pressure in an eye during a predetermined time interval. This allows maintenance of normal intraocular pressure during glaucoma surgery. A pressure regulator of the spring-biassed diaphragm type is provided with additional bias by a column of liquid. The hypodermic needle can be safely inserted into the anterior chamber of the eye. Liquid is then bled out of the column to reduce the bias on the diaphragm of the pressure regulator and, consequently, the output pressure of the regulator. This lowering pressure of the regulator also occurs in the eye by means of a small second bleed path provided between the pressure regulator and the hypodermic needle.
An example of how modern engineering and safety techniques can be used to assure the reliable and safe operation of photovoltaic power systems is presented. This particular application is for a solar cell power system demonstration project designed to provide electric power requirements for remote villages. The techniques utilized involve a definition of the power system natural and operating environment, use of design criteria and analysis techniques, an awareness of potential problems via the inherent reliability and FMEA methods, and use of fail-safe and planned spare parts engineering philosophy.
A method and apparatus for safely reducing abnormally high intraocular pressure in an eye during a predetermined time interval is presented. This allows maintenance of normal intraocular pressure during glaucoma surgery. According to the invention, a pressure regulator of the spring biased diaphragm type is provided with additional bias by a column of liquid. The height of the column of liquid is selected such that the pressure at a hypodermic needle connected to the output of the pressure regulator is equal to the measured pressure of the eye. The hypodermic needle can then be safely inserted into the anterior chamber of the eye. Liquid is then bled out of the column to reduce the bias on the diaphragm of the pressure regulator and, consequently, the output pressure of the regulator. This lowering pressure of the regulator also occurs in the eye by means of a small second bleed path provided between the pressure regulator and the hypodermic needle. Alternately, a second hypodermic needle may be inserted into the eye to provide a controlled leak off path for excessive pressure and clouded fluid from the anterior chamber.
Safe reentry of the shuttle orbiter requires that the payload bay doors be closed and securely latched. Since a malfunction in the door drive or bulkhead latch systems could make safe reentry impossible, the requirement to provide tools to manually close and secure the doors was implemented. The tools would disconnect a disabled door or latch closure system and close and secure the doors if the normal system failed. The tools required to perform these tasks have evolved into a set that consists of a tubing cutter, a winch, a latching tool, and a bolt extractor. The design, fabrication, and performance tests of each tool are described.
This paper describes an example of how modern engineering and safety techniques can be used to assure the reliable and safe operation of photovoltaic power systems. This particular application was for a solar cell power system demonstration project in Tangaye, Upper Volta, Africa. The techniques involve a definition of the power system natural and operating environment, use of design criteria and analysis techniques, an awareness of potential problems via the inherent reliability and FMEA methods, and use of a fail-safe and planned spare parts engineering philosophy.
The slidewire emergency egress system is designed to provide a fast and safe egress means for the shuttle flight crew, passengers, and ground closeout crew in the event of imminent danger while the space vehicle is still on the launch pad. Egress is from the 195 ft. level of the fixed service structure (FSS) to a ground landing area 1200 ft. away from the launch site. The slidewire design is such that the flight crew and passengers can be evacuated to a safe area within two minutes with winds as high as 34 knots from any direction.
Light reflection produced by the satellite power system and the possible effects of that light on the human eye, plants, and animals were studied. For the human eye, two cases of reflected light, might cause eye damage if viewed for too long. These cases are: (1) if, while in low Earth orbit, the orbital transfer vehicle is misaligned to reflect the Sun to Earth there exists a maximum safe fixation time for the naked eye of 42.4 secs; (2) reflection from the aluminum paint on the back of the orbital transfer vehicle, while in or near low Earth orbit, can be safely viewed by the naked eye for 129 sec. For plants and animals the intensity and timing of light are not a major problem. Ways for reducing and/or eliminating the irradiances are proposed.
Global geometric shapes such as lines, planes, circles, spheres, cylinders, and the associated computational algorithms which provide relatively inexpensive estimates of minimum spatial clearance for safe operations were selected. The Space Shuttle, remote manipulator system, and the Power Extension Package are used as an example. Robotic mechanisms operate in quarters limited by external structures and the problem of clearance is often of considerable interest. Safe clearance management is simple and suited to real time calculation, whereas contact prediction requires more precision, sophistication, and computational overhead.
Thin cells processed and stored safely. Major parts of handling fixture hold components of solar cell array modules safely, yet allow assembly process to proceed without interference. Fixture used with or without internal vacuum. Concept allows handling of thin, relatively-fragile cells, and offers potential for savings in silicon material and cost.
Results of an experiment investigating overdischarge behavior of two types of Li/SO2 cells are presented. Forced overdischarges of the Li/LiBr, CH3CN/SO2 cell can result in unsafe behavior such as venting with fire and release of toxic gases. The hazards may be minimized or eliminated by careful cell design considerations and practice of high standards of quality contol in cell manufacture. Seemingly safe cells at 25 C when forced overdischarged at -25 C, even at low currents, exhibited incipient signs of hazards. Their cathodes indicated signs of shock sensitivity. Cathode limited Li/SOCl2 cells were safe during forced overdischarge for long periods of time. Lithium limited Li/SOCl2 cells in which practically all Li had been used up before cell reversal did not exhibit hazardous behavior. Anode limited Li/SOCl2 cells, but not Li limited, exhibited detonations, all during overdischarges at relatively low current densities of or = 1 mA/sq cm 2. Anode potentials 4v with large oscillations preceeded the events. The events were confined to the anode and the temperature rose high enough to melt Ni grids.
Long, heavy loads handled safely. Forklift support dolly enables operator to manipulate safely large sections of materials around corners and through narrow aisles and doorways. Dolly has pivoting tandem wheels for maneuverability. Plate laid out lengthwise along truck axis, with one end clamped to forklift and other end clamped to dolly. With this arrangement, minimum width of passage determined by short side of plate rather than by long side.
The dynamic characteristics of the Solar Array Flight Experiment (SAFE) structure during deployment and retraction are investigated. The SAFE structure consists of a deployable mast with an attached solar blanket designed with accordion type folds to permit packaging in a small volume. The planar form of the blanket geometry during deployment is maintained by a blanket tension/guidewire system. Structurally, the mast is modeled as an Euler beam column with inplane and out of plane bending and finite torsional stiffness. For out of plane motion, the blanket is modeled as a distributed mass uniformly supported by the three guidewires. For inplane motion the blanket displacements are assumed to vary linearly from the mast base to the mast tip. The mathematical model uses a virtual work formulation, required because the axial loading on the mast is nonconservative, combined with assumed beam modes to derive the differential equations of motion. Consideration of the time dependent boundary conditions results in an infinite set of ODE with time dependent coefficients. Finally, correlation of mast tip accelerations to mast base bending moments for specified modal motions are indicated.