SEARCH · Search NASA
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
A solar photovoltaic satellite based upon the utilization of a GaAlAs solar cell is defined. Topics covered include silicon-based photovoltaics, solar thermal power conversion, microwave energy transmission, power distribution, structures, attitude control and stationkeeping, thermal, and information management and control.
The results of a survey of the ocean/coastal zone community to determine potential applications of a High Altitude Powered Platform (HAPP) are reported. Such a platform, capable of stationkeeping for periods up to a year over a given location, could make frequent and repeated high resolution observations over a given region or serve as a high-altitude regional communications link. Users were surveyed in person and via a questionnaire to determine the desirability of the HAPP within the ocean/coastal zone community. The results of the survey indicated that there is strong interest in all areas of the user community (research and development, operational agencies, and private industry) in having NASA develop the HAPP.
Operational and physical requirements were investigated for a low-light-level viewing device to be used as a window-mounted optical sight for crew use in the pointing, navigating, stationkeeping, and docking of space vehicles to support space station operations and the assembly of large structures in space. A suitable prototype, obtained from a commercial vendor, was subjected to limited tests to determine the potential effectiveness of a proximity optical device in spacecraft operations. The constructional features of the device are discussed as well as concepts for its use. Tests results show that a proximity optical device is capable of performing low-light-level viewing services and will enhance manned spacecraft operations.
The results of a survey of the ocean/coastal zone community conducted for the NASA Wallops Flight Center to identify potential applications of a high altitude powered platform (HAPP) are presented. Such a platform would stationkeep at 70,000 feet for up to a year over a given location and make frequent high resolution observations, or serve as a regional communications link. The survey results indicate user interest among scientific researchers, operational agencies and private industry. It is felt that such a platform would combine the desirable characteristics of both geostationary satellites (wide area, frequent observation) and aircraft (high resolution). As a result a concept for an operational HAPP system in the form of a 'mesoscale geostationary satellite' system evolved. Such a system could employ many of the same technologies used in current NASA and NOAA geostationary satellite programs. A set of generalized instrument requirements for HAPP borne sensors is also presented.
On August 12, 1978, a scientific spacecraft called International Sun-Earth Explorer-3 (ISEE-3) was launched towards the interior sun-earth libration point, L1. The spacecraft was placed into a 'halo orbit' around the L1 point on November 20, 1978, thus becoming the first libration-point satellite. During its 100-day transfer trajectory, ISEE-3 lingered in a region where the gravitational effects of the sun and the earth are comparable, leading to some interesting tradeoffs concerning the maneuver strategy for halo-orbit insertion. Following orbit insertion, stationkeeping maneuvers were required to maintain the delicate equilibrium in the halo orbit. Details are presented for all of the velocity change maneuvers that were executed prior to the completion of the first halo orbit on May 14, 1979. Orbit selection, trajectory design, and the scientific objectives of the ISEE-3 mission are also discussed.
The satellite power systems point design concept is described. The concept definition includes satellite, ground and space systems, and their relationships. Emphasis is placed on the definition of the GaAlAs photovoltaic satellite system. The major subsystems of the satellite system including power conversion, power distribution and control, microwave, attitude control and stationkeeping, thermal control, structures, and information management and control are discussed.
Procedures and techniques are discussed for retrieving payloads that are inertially or local vertical/local horizontal (LVLH) stabilized. Selection of the retrieval profile to be used depends on several factors: (1) control authority of the payload, (2) payload sensitivity to primary reaction control system (PRCS) plumes, (3) whether the payload is inertially or LVLH stabilized, (4) location of the grapple fixture, and (5) orbiter propellant consumption. The general retrieval profiles recommended are a V-bar approach for payloads that are LVLH or gravity-gradient stabilized, and the V-bar approach with one or two phase flyaround for inertially stabilized payloads. Once the general type of profile has been selected, the detailed retrieval profile and timeline should consider the various guidelines, groundrules, and constraints associated with a particular payload or flight. Reaction control system (RCS) propellant requirements for the recommended profiles range from 200 to 1500 pounds, depending on such factors as braking techniques, flyaround maneuvers (if necessary), and stationkeeping operations. The time required to perform a retrieval (starting from 1000 feet) varies from 20 to 130 minutes, depending on the complexity of the profile. The goals of this project are to develop a profile which ensures mission success; to make the retrieval profiles simple; and to keep the pilot workload to a minimum by making use of the automatic features of the orbiter flight software whenever possible.
Top level trade studies are presented, including comparison of solid state and klystron concepts, higher concentration on the solar cells, composite and aluminum structure, and several variations to the reference concept. Detailed trade studies are presented in each of the subsystem areas (solar array, power distribution, structures, thermal control, attitude control and stationkeeping, microwave transmission, and ground receiving station). A description of the selected point design is also presented.
Recent studies of the self-field magnetoplasmadynamic (MPD) thruster indicate that the attainable value of thrust efficiency can be over 50% with argon propellant at 5000 sec. Projections for hydrogen propellant show that the specific impulse may exceed 10,000 sec. Improving performance projections such as these create a need for systems and applications studies to be updated. This paper reviews the configurations for an MPD propulsion system and those missions on which such a system might find application. An MPD propulsion system could be used for: (1) attitude control and stationkeeping of large space structures, (2) interorbit transportation, and (3) interplanetary propulsion. A trajectory analysis of a Saturn Orbiter using a nuclear power supply and an MPD propulsion system is presented. A LEO to GEO MPD-OTV concept is presented that uses a remote source transmitting power to the OTV in the form of microwaves. Trajectory analysis of this latter concept indicates that a payload of 20,000 kg can be delivered to GEO in about 20 days if the MPD propulsion system receives 20 MW of input power.
Basic technology in the design, mechanization, and analysis of control systems for large flexible space structures was examined. The focus of the platform control effort was on pointing control. The reason for this emphasis was because of the unique problems in this area posed by multiple independent experiment packages operating simultaneously on a single platform. Attitude control and stationkeeping were also addressed for future consideration.
Modifications to the reference concept were studied and the best approaches defined. The impact of the high efficiency multibandgap solar array on the reference concept design is considered. System trade studies for several solid state concepts, including the sandwich concept and a separate antenna/solar concept, are described. Two solid state concepts were selected and a design definition is presented for each. Magnetrons as an alternative to the reference klystrons for dc/RF conversion are evaluated. System definitions are presented for the preferred klystron and solid state concepts. Supporting systems are analyzed, with major analysis in the microwave, structures, and power distribution areas. Results of studies for thermal control, attitude control, stationkeeping, and details of a multibandgap solar cell study are included. Advanced laser concepts and the meteorological effects of a laser beam power transmission concept are considered.
The Space Operations Center will have 3 primary missions: (1) construction of large satellites and platforms, (2) flight support of orbital transfer vehicles, including manned and unmanned vehicles, and (3) satellite servicing, including tending of attached payload modules, spacecraft stationkeeping with the SOC, and remotely located satellites. This paper describes some of the facilities, equipment, and operations involved in conducting these missions. The data described in this paper are from an on-going system analysis study and therefore should not be considered as final.
A nonlinear, multibody, six-degrees-of-freedom digital simulation has been developed to study generic Heavy Lift Airship (HLA) dynamics and control. The basic aerodynamic functions developed to model the hull, tail, and rotor loads continuously over all incidence ranges are reviewed and applied to a Quadrotor HLA with a low fineness ratio hull and a small vee-tail. Trim calculations for a test vehicle suggest control power deficiencies in crosswind stationkeeping for the unloaded vehicle. Gust responses show the importance of correctly calculating loads due to accelerated relative motion of air and hull. Numerically linearized dynamics for the test vehicle show the existence of a divergent yaw mode, and an oscillatory pitch mode whose stability characteristics are sensitive to flight speed. A considerable improvement in the vehicle's stability and response results from a simple multi-axis closed-loop control system operating on the rotors and propeller blades.
The five major tasks of the program are reported. Task 1 is a literature search followed by selection and definition of seven generic spacecraft classes. Task 2 covers the determination and description of important disturbance effects. Task 3 applies the disturbances to the generic spacecraft and adds maneuver and stationkeeping functions to define total auxiliary propulsion systems requirements for control. The important auxiliary propulsion system characteristics are identified and sensitivities to control functions and large space system characteristics determined. In Task 4, these sensitivities are quantified and the optimum auxiliary propulsion system characteristics determined. Task 5 compares the desired characteristics with those available for both electrical and chemical auxiliary propulsion systems to identify the directions technology advances should take.
Possible missions requiring multimegawatt photovoltaic space power systems in the 1990's time frame and associated power system technology needs are examined. The following concepts for photovoltaic power approaches are considered: planar arrays, concentrating arrays, hybrid systems using Rankine engines, thermophotovoltaic and AC/DC power management approaches, battery, fuel cell, flywheel energy storage, and interactions with the electrical ion engine injection and stationkeeping system. The levels of modularity for efficient, safe, constructable, serviceable, and cost effective system design are analyzed, and the benefits of alternate approaches developed. Both manned low Earth orbit and unmanned geosynchronous Earth orbit applications were examined for technological development. Technology developments applicable to power systems which appear to have benefits independent of the absolute power level are suggested.
Possible missions requiring multimegawatt photovoltaic space power systems in the 1990's time frame and power system technology needs associated with these missions are examined. Four specific task areas were considered: (1) missions requiring power in the 1-10 megawatt average power region; (2) alternative power systems and component technologies; (3) technology goals and sensitivity trades and analyses; and (4) technology recommendations. Specific concepts for photovoltaic power approaches considered were: planar arrays, concentrating arrays, hybrid systems using Rankine engines, thermophotovoltaic approaches; all with various photovoltaic cell component technologies. Various AC/DC power management approaches, and battery, fuel cell, and flywheel energy storage concepts are evaluated. Interactions with the electrical ion engine injection and stationkeeping system are also considered.
A detailed system model of a VTOL aircraft approaching a small aviation facility ship was developed and used to investigate several approach guidance concepts. A preliminary anaysis of the aircraft-vessel landing guidance requirements was conducted. The various subelements and constraints of the flight system are described including the landing scenario, lift fan aircraft, state rate feedback flight control, MLS-based navigation, sea state induced ship motion, and wake turbulence due to wind-over-deck effects. These elements are integrated into a systems model with various guidance concepts. Guidance is described in terms of lateral, vertical, and longitudinal axes steering modes and approach and landing phases divided by a nominal hover (or stationkeeping) point defined with respect to the landing pad. The approach guidance methods are evaluated, and the two better steering concepts are studied by both single pass and Monte Carlo statistical simulation runs. Four different guidance concepts are defined for further analysis for the landing phase of flight.
The high power self field MPD thruster uses electromagnetic forces rather than electrostatic to accelerate a neutral plasma. The most attractive application of MPD thrusters to satellite power systems is in the area of electric propulsion for a cargo orbit transfer vehicle (COTV). Calculations were performed in order to compare the performance of a COTV using an ion or MPD propulsion system. Results show that the MPD propulsion system gives a shorter trip time with the same power and payload when compared to the ion thruster propulsion system at either value of specific impulse. More important than the trip time benefit may be the advantage a MPD propulsion system provides in system simplicity. Another interesting COTV concept using MPD thrusters is the use of a remote power supply located on the Earth, at GEO, or somewhere in between to transmit power to the COTV in a microwave transmission. The specific impulse at thrust levels of tens of newtons makes a MPD propulsion system a candidate for stationkeeping and attitude control of large space structures such as a SPS.