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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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At least 1,351 records · Page 75

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NASA NTRS1983

Tethers open new space options

Several examples of possible applications of the tethering concept in space are examined. In particular, attention is given to a practical design of a 500-kg satellite system to be tethered at a distance of 100 km from the Space Shuttle. The satellite body has the form of a sphere, aerodynamically stabilized and fitted with a dockline adapter that mates with a capture mechanism at the tip of an extendable boom; the tether is a very flexible synthetic line 1-2 mm in diameter. Other applications include a wholly passive stable platform created by tethering two rows of empty Shuttle External Tanks or similar masses 10-20 km apart, a remote docking port for a space station, and constellations of space objects, with tethers used to tie them together and constrain their relative motions.

Bekey, I.↗

NASA NTRS1983

A FMCW Radar Ranging Device for the Teleoperator Maneuvering System

A frequency-modulated continuous wave radar system is under development in the Communications Systems Branch of the Information and Electronic Systems Laboratory at Marshall Space Flight Center. The radar unit is being designed for use on the teleoperator maneuvering system. Its function is to provide millimeter-level accuracy in range and range rate measurements out to a range of thirty meters. This will facilitate soft docking with accuracy. This report is an updating of previous developments reported on this system. An innovation in the system is the utilization of a standard reference signal generated by shunting a portion of the radar energy into a shorted coaxial delay line. The regular radar target return signal is constantly compared with the reference signal to provide internal error compensation. Within a five meter range, a limit imposed by present laboratory dimensions, the radar system exhibits reliable accuracy with range error less than 0.2%.

Mcdonald, M. W.↗

NASA NTRS1984

Development of Test Article Building Block (TABB) for deployable platform systems

The concept of a Test Article Building Block (TABB) is described. The TABB is a ground test article that is representative of a future building block that can be used to construct LEO and GEO deployable space platforms for communications and scientific payloads. This building block contains a main housing within which the entire structure, utilities, and deployment/retraction mechanism are stowed during launch. The end adapter secures the foregoing components to the housing during launch. The main housing and adapter provide the necessary building-block-to-building-block attachments for automatically deployable platforms. Removal from the shuttle cargo bay can be accomplished with the remote manipulator system (RMS) and/or the handling and positioning aid (HAPA). In this concept, all the electrical connections are in place prior to launch with automatic latches for payload attachment provided on either the end adapters or housings. The housings also can contain orbiter docking ports for payload installation and maintenance.

Greenberg, H. S.↗

NASA NTRS1984

Attitude, control and stabilization

In the area of control, several problems can arise during the evolution of the space station. These incude: 1) the use of multiple or articulated flexible bodies; 2) the need for distributed cntrol for maneuvering and maintaining altitude; 3) hierarchical control to automate and manage control systems; 4) structual control (from the standpoint of appendage stamping; isolation, and possible figure control); 5) cntrol position and orientation for component modules during construction (an evolutionary requirement); 6) control during docking and undocking operations; and 7) the normal requirements for stablity and control during systems operations. In addition, there are a number of key technology concerns, such as significant landing modes which tend to be closely spaced and distributed widely, distributed sensors and actuators which are collecated, and the wide distribution of landing modes that must be reduced from a dimensional standpoint.

Morais, B. G.↗

NASA NTRS1983

Polarized-interferometer feasibility study

The feasibility of using a polarized-interferometer system as a rendezvous and docking sensor for two cooperating spacecraft was studied. The polarized interferometer is a radio frequency system for long range, real time determination of relative position and attitude. Range is determined by round trip signal timing. Direction is determined by radio interferometry. Relative roll is determined from signal polarization. Each spacecraft is equipped with a transponder and an antenna array. The antenna arrays consist of four crossed dipoles that can transmit or receive either circularly or linearly polarized signals. The active spacecraft is equipped with a sophisticated transponder and makes all measurements. The transponder on the passive spacecraft is a relatively simple repeater. An initialization algorithm is developed to estimate position and attitude without any a priori information. A tracking algorithm based upon minimum variance linear estimators is also developed. Techniques to simplify the transponder on the passive spacecraft are investigated and a suitable configuration is determined. A multiple carrier CW signal format is selected. The dependence of range accuracy and ambiguity resolution error probability are derived and used to design a candidate system. The validity of the design and the feasibility of the polarized interferometer concept are verified by simulation.

Raab, F. H.↗

NASA NTRS1982

Shuttle interaction study extension

The following areas of Space Shuttle technology were discussed: variable altitude strategy, spacecraft servicing, propellant storage, orbiter plume impingement, space based design, mating (docking and berthing), shuttle fleet utilization, and mission/traffic model.

Source record↗

NASA NTRS1983

Tanker orbit transfer vehicle and method

A method and apparatus for transportation between orbits are presented. A tanker orbit transfer vehicle includes two stages each of which includes a fuel container. The first stage may be left in an intermediate parking orbit while the second stage goes on to carry out a mission, thereafter to return to rendezvous and dock with the first stage. Fuel carried by the first stage may be utilized for travel of the two stages between the starting orbit and the parking orbit, and for return to the starting orbit. An aerobrake may be included in the system for use in the return to the initial orbit.

Ryan, G. G.↗

NASA NTRS1984

System definition study of deployable, non-metallic space structures

The state of the art for nonmetallic materials and fabrication techniques suitable for future space structures are summarized. Typical subsystems and systems of interest to the space community that are reviewed include: (1) inflatable/rigidized space hangar; (2) flexible/storable acoustic barrier; (3) deployable fabric bulkhead in a space habitat; (4) extendible tunnel for soft docking; (5) deployable space recovery/re-entry systems for personnel or materials; (6) a manned habitat for a space station; (7) storage enclosures external to the space station habitat; (8) attachable work stations; and (9) safe haven structures. Performance parameters examined include micrometeoroid protection; leakage rate prediction and control; rigidization of flexible structures in the space environment; flammability and offgassing; lifetime for nonmetallic materials; crack propagation prevention; and the effects of atomic oxygen and space debris. An expandable airlock for shuttle flight experiments and potential tethered experiments from shuttle are discussed.

Stimler, F. J.↗

NASA NTRS1984

Computer vision for real-time orbital operations. Center directors discretionary fund

Machine vision research is examined as it relates to the NASA Space Station program and its associated Orbital Maneuvering Vehicle (OMV). Initial operation of OMV for orbital assembly, docking, and servicing are manually controlled from the ground by means of an on board TV camera. These orbital operations may be accomplished autonomously by machine vision techniques which use the TV camera as a sensing device. Classical machine vision techniques are described. An alternate method is developed and described which employs a syntactic pattern recognition scheme. It has the potential for substantial reduction of computing and data storage requirements in comparison to the Two-Dimensional Fast Fourier Transform (2D FFT) image analysis. The method embodies powerful heuristic pattern recognition capability by identifying image shapes such as elongation, symmetry, number of appendages, and the relative length of appendages.

Vinz, F. L.↗

NASA NTRS1984

The role of the Shuttle Engineering Simulator in the Solar Max rescue mission

Background information concerning the makeup of the SES, the role it traditionally plays in support of the Shuttle Program, its capabilities and the specific work performed on the simulator during the sixteen months proceedings the Solar Max repair mission is presented. The SES plays a significant role in the preparations for the STS 41-C Solar Max repair mission and during the mission in the development of the plan and procedures to retrieve the satellite after the MMU docking attempts failed. The development of the on orbit simulation capabilities required to support this mission is to a very large extent simply an expansion of the capabilities designed into the SES to support previous engineering simulation requirements for the Space Shuttle program.

St.john, R. H.↗

NASA NTRS1983

Overview of NASA space station activities

The architecture, functions, and human activities on-board a space station are discussed. A manned presence is regarded as essential for innovative actions and successful exploitation of weightless conditions. The station itself could be a cluster of modules for habitation, power, operations, docking, experimentation, and storage. Additionally, the station could provide an interface for free-flying platforms and teleoperated satellite services, as well as a base for establishing space-based manufacturing facilities. NASA has projected timelines that include initial development funding in 1987, full capabilities before the year 2000, and initial costs for minimum capabilities of $7.5-9 billion. Architecture, mission requirements, trade-offs, and concepts are currently being defined as a prelude to systems development. Attention is being given to participation by both the DoD and other governments, and to defining the capabilities of the station, including habitability, closed-loop life-support system, the scope of science application and data transfer, and the power requirements.

Tilton, E. L., III↗

NASA NTRS1984

Mars exploration in the 1990's

Science objectives for a Mars exploration program in the 1990s, set forth by NASA's Committee on Planetary Exploration, are presented. They include: an intensive study of the Martian surface, the exploration of the structure and general circulation of the atmosphere, the exploration of the nature and dynamics of the planet's interior, the nature of Mars's magnetic field, the character of the upper atmosphere and its interaction with the solar wind, and the establishment of the global chemical and physical characteristics of the Martian surface. Several low cost missions, which have been suggested by the Committee for NASA's CORE program, such as the Mars Geoscience Climatology Observer, the Mars Aeronomy Orbiter, and the Mars Surface Network and Surface Probing missions are also covered. Direct Entry-Direct Return and Out-of-Orbit Entry-Orbital Rendezvous and Docking are two versions of a Mars Rover and Sample Return (MRSR) mission discussed in detail. It is concluded that a MRSR mission will require the combination of full Centaur capability, aerocapture at Mars and earth, and direct return to earth to meet major scientific goals. Further studies should be made in orbit assembly, fuel transfer technology, aeromaneuvering, terminal guidance, rover technology, and robotics.

Albee, A. L.↗

NASA NTRS1984

The space station program plan

The strategy that has been adopted for the NASA permanent manned space station development program is to provide a source of different modular components. Virtually any tactical requirements can then be accommodated through the specification of the appropriate inventory of orbitally assembled modular components. Some of the space station's subsystems are common to several elements, and must therefore be generally compatible, offering consistent interfaces with, for example, the Space Shuttle Orbiter. Tethered systems, including small platforms for controlled micro-g experiments, will be incorporated, and the occasional presence of two docked Space Shuttle Orbiters will be allowed for.

Hodge, J. D.↗

NASA NTRS1984

Navigation and control considerations for space based orbital maneuvering systems

Various design areas of concern in navigation and control of space-based orbital maneuvering systems such as those on the Orbiter are discussed, with note taken of approach maneuvers. Design problems occur in the areas of storage modes, sensing, activation methods, navigation, target/mission determination, rendezvous and docking schemes, reliability, and commonality between low- and high-energy maneuvering vehicles. Navigation may be in autonomous or nonautonomous modes and may include ground-baed computations and commands via the TDRSS or NORAD systems. Autonomous operations would interface with the GPS. All the concepts discussed are significant for the planned orbital transfer and orbital maneuvering vehicles, which would be used to place satellites in orbit and repair or retrieve them.

Brandon, L.↗

NASA NTRS1985

Tethers Open New Space Options

The fundamentals of tether action are discussed with focus on the forces acting on tethered masses and a tethered satellite system being developed for deployment from the space shuttle is examined. The static, dynamic, and electric properties of the tether can be exploited for use in the long term observation of phenomena of the lower troposphere; as a space based wind tunnel; to generate high electrodynamic power; to provide desirable gravity for the space station; to dock orbit transfer vehicles with the space station; and to form a constellation of space platforms tied to the space station. Italy is responsible for building and integrating the satellite. NASA is involved in building the deployer and integrating the tethered satellite system with the space shuttle.

Bekey, I.↗

NASA NTRS1985

Tether Fundamentals

Forces on tethered satellites, tether tension as a function of the effective mass, and parameters of candidate tether materials are examined. Illustrations show: stabilization control law; tethered satellite deployment and retrieval; angular momentum; electric motor effect reboost; a very long tether phenomenon; shuttle tethered satellite effects on the orbiter; artificial gravity; tethered satellite rendezvous docking relative velocity; and scaling up from the shuttle/TSS. Limitations of the tethered satellite system and of tether properties as well as cost/benefits trades for future applications are considered.

Rupp, C.↗

NASA NTRS1985

Transportation Applications, Part 1

The applications of tethers in support of space transportation is divided into: (1) orbit transfer, momentum transfer release/rendezvous (hanging, swinging, and spinning) and simplified docking; (2) orbit maintenance: electrodynamic thrust in or out of plane, electrodynamic libration pumping or damping, momentum scavenging, and isolate thruster exhaust; and (3) transfer within constellation: deployment or retrieval of whole constellation, clothesline loop, hoist, tram for travel on the tether, monkey between the tethers, and power and fluid transfer.

Carroll, J.↗

NASA NTRS1985

Summary Presentation of the Transportation Panel

Space mission scenarios are presented in which tethering is utilized. The technical and cost benefits are considered along with practicality and operational requirements. The mission scenarios considered include: (1) space shuttle delivery of payloads to higher orbits; (2) the downward release of the external tank from a shuttle; (3) space station altitude reboost using shuttle angular momentum; (4) shuttle docking to space station tether; (5) using shuttle based tether to assist launch of upper stage to higher energy orbits; (6) using space station tether to deploy payloads to higher orbits with momentum accumulator; (7) using tethers to discard first stages or apogee motors; and (8) planetary applications of tethers.

Hunter, M. W.↗