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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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NASA NTRS1989

The Space Station Freedom - International cooperation and innovation in space safety

The Space Station Freedom (SSF) being developed by the United States, European Space Agency (ESA), Japan, and Canada poses novel safety challenges in design, operations, logistics, and program management. A brief overview discloses many features that make SSF a radical departure from earlier low earth orbit (LEO) space stations relative to safety management: size and power levels; multiphase manned assembly; 30-year planned lifetime, with embedded 'hooks and scars' forevolution; crew size and skill-mix variability; sustained logistical dependence; use of man, robotics and telepresence for on-orbit maintenance of station and free-flyer systems; closed-environment recycling; use of automation and expert systems; long-term operation of collocated life-sciences and materials-science experiments, requiring control and segregation of hazardous and chemically incompatible materials; and materials aging in space.

Rodney, George A.↗

NASA NTRS1990

Ion drag for a negatively biased solar array in low earth orbit

Highly biased solar arrays in the space environment are found to have a number of significant interactions with the space environment. The enhanced drag suffered by highly biased solar arrays is studied with the particle-in-cell code. The results are compared to recent numerical work. The drag calculations contain the effect of having the conductor surrounded by dielectrics as well as the charging of the dielectric by electrons. The results are used to calculate the attitude change expected on the high-voltage solar array of the Japanese Space Flyer Unit.

Hastings, Daniel E.↗

NASA NTRS1990

Space Station Freedom avionics technology

The Space Station Freedom Program (SSFP) encompasses the design, development, test, evaluation, verification, launch, assembly, and operation and utilization of a set of spacecraft in low earth orbit (LEO) and their supporting facilities. The spacecraft set includes: the Space Station Manned Base (SSMB), a European Space Agency (ESA) provided Man-Tended Free Flyer (MTFF) at an inclination of 28.5 degrees and nominal attitude of 410 km, a USA provided Polar Orbiting Platform (POP), and an ESA provided POP in sun-synchronous, near polar orbits at a nominal altitude of 822 km. The SSMB will be assembled using the National Space Transportation System (NSTS). The POPs and the MTFF will be launched by Expendable Launch Vehicles (ELVs): a Titan 4 for the US POP and an Ariane for the ESA POP and MTFF. The US POP will for the most part use derivatives of systems flown on unmanned LEO spacecraft. The SSMB portion of the overall program is presented.

Edwards, A.↗

NASA NTRS1986

Space station: The next logical step

The following topics with respect to the space station program are discussed: (1) unmanned free-flyers; (2) recent progress; (3) the space shuttle; (4) international participation; (5) science, commerce, and technology; and (6) private sector participation.

Stofan, Andrew J.↗

NASA NTRS1990

Results from teleoperated free-flying spacecraft simulations in the Martin Marietta space operations simulator lab

To augment the capabilities of the Space Transportation System, NASA has funded studies and developed programs aimed at developing reusable, remotely piloted spacecraft and satellite servicing systems capable of delivering, retrieving, and servicing payloads at altitudes and inclinations beyond the reach of the present Shuttle Orbiters. Since the mid 1970's, researchers at the Martin Marietta Astronautics Group Space Operations Simulation (SOS) Laboratory have been engaged in investigations of remotely piloted and supervised autonomous spacecraft operations. These investigations were based on high fidelity, real-time simulations and have covered a wide range of human factors issues related to controllability. Among these are: (1) mission conditions, including thruster plume impingements and signal time delays; (2) vehicle performance variables, including control authority, control harmony, minimum impulse, and cross coupling of accelerations; (3) maneuvering task requirements such as target distance and dynamics; (4) control parameters including various control modes and rate/displacement deadbands; and (5) display parameters involving camera placement and function, visual aids, and presentation of operational feedback from the spacecraft. This presentation includes a brief description of the capabilities of the SOS Lab to simulate real-time free-flyer operations using live video, advanced technology ground and on-orbit workstations, and sophisticated computer models of on-orbit spacecraft behavior. Sample results from human factors studies in the five categories cited above are provided.

Hartley, Craig S.↗

NASA NTRS1991

SSSFD manipulator engineering using statistical experiment design techniques

The Satellite Servicer System Flight Demonstration (SSSFD) program is a series of Shuttle flights designed to verify major on-orbit satellite servicing capabilities, such as rendezvous and docking of free flyers, Orbital Replacement Unit (ORU) exchange, and fluid transfer. A major part of this system is the manipulator system that will perform the ORU exchange. The manipulator must possess adequate toolplate dexterity to maneuver a variety of EVA-type tools into position to interface with ORU fasteners, connectors, latches, and handles on the satellite, and to move workpieces and ORUs through 6 degree of freedom (dof) space from the Target Vehicle (TV) to the Support Module (SM) and back. Two cost efficient tools were combined to perform a study of robot manipulator design parameters. These tools are graphical computer simulations and Taguchi Design of Experiment methods. Using a graphics platform, an off-the-shelf robot simulation software package, and an experiment designed with Taguchi's approach, the sensitivities of various manipulator kinematic design parameters to performance characteristics are determined with minimal cost.

Barnes, John↗

NASA NTRS1991

Retrievable Payload Carrier (RPC): Next generation Long Duration Exposure Facility

The Retrievable Payload Carrier (RPC) is described which is a multi-experiment, free-flyer spacecraft being privately developed to make in-space experimentation more accessible and economically feasible for research and development organizations. The carrier concept was derived from NASA's highly successful and flight proven Long Duration Exposure Facility (LDEF). The LDEF capabilities were enhanced to meet new customer requirements. This reusable payload carrier is planned for launch and retrieval by the space shuttle on a regular basis. The RPC's compact design facilitates flexible manifesting of the shuttle cargo bay space, thereby, permitting timely launches and retrievals. The vehicle is designed so that either the entire carrier can be retrieved from orbit, or individual experiment pallets can be removed and replaced in orbit. This gives customers even greater control over their experiment recoveries. A fully operational RPC System consists of: (1) a carrier spacecraft; (2) a ground control station for communication with customer payloads and the carrier; (3) a ground processing facility to provide refurbishment, final checkout, and integration of customer payloads and the carrier; and (4) the personnel required to support both the development and operation phases of the program. Customer payloads will fly 6 to 18 month missions, or longer, as required. Spreading launch, operations, and retrieval costs over multiple experimental payloads results in minimized customer costs. The RPC Program's initial objective is to operate a simple carrier system which meets basic customer service needs.

Perry, Arthur T.↗

NASA NTRS1991

Pressurization and expulsion of cryogenic liquids: Generic requirements for a low gravity experiment

Requirements are presented for an experiment designed to obtain data for the pressurization and expulsion of a cryogenic supply tank in a low gravity environment. These requirements are of a generic nature and applicable to any cryogenic fluid of interest, condensible or non-condensible pressurants, and various low gravity test platforms such as the Space Shuttle or a free-flyer. Background information, the thermophysical process, preliminary analytical modeling, and experimental requirements are discussed. Key parameters, measurements, hardware requirements, procedures, a test matrix, and data analysis are outlined.

Vandresar, Neil T.↗

NASA NTRS1991

Dynamic tensile-failure-induced velocity deficits in rock

Planar impact experiments were employed to induce dynamic tensile failure in Bedford limestone. Rock disks were impacted with aluminum and polymethyl methacralate (PMMA) flyer plates at velocities of 10 to 25 m/s. Tensile stress magnitudes and duration were chosen so as to induce a range of microcrack growth insufficient to cause complete spalling of the samples. Ultrasonic P- and S-wave velocities of recovered targets were compared to the velocities prior to impact. Velocity reduction, and by inference microcrack production, occurred in samples subjected to stresses above 35 MPa in the 1.3 microsec PMMA experiments and 60 MPa in the 0.5 microsec aluminum experiments. Using a simple model for the time-dependent stress-intensity factor at the tips of existing flaws, apparent fracture toughnesses of 2.4 and 2.5 MPa sq rt m are computed for the 1.3 and 0.5 microsec experiments. These are a factor of about 2 to 3 greater than quasi-static values. The greater dynamic fracture toughness observed may result from microcrack interaction during tensile failure. Data for water-saturated and dry targets are indistinguishable.

Rubin, Allan M.↗

NASA NTRS1991

Orbital station-keeping for multiple spacecraft interferometry

This paper presents a three-satellite station-keeping strategy that is applicable to very long (1-100 km) baseline optical interferometry in space using the 'free-flyer' approach. The relative positions of the satellites in an arbitrarily oriented inertial coordinate system are described parametrically, and the continuous thrust vectors required to follow the paths are derived. The paths, which are constrained to be in the U-V plane of an astronomical source (a plane perpendicular to the direction of the source), are always chosen to maximize the use of gravity gradient forces and minimize the use of thrusting which can easily be provided by ion thrusters. Two different thrust programs are presented. One allows the interferometer to take data over an elliptic-shaped area of the U-V plane of arbitrary size for astronomical sources in any direction except close to the orbit plane of the system. The second thrust program reorients the U-V plane from one arbitrary source direction to another.

Decou, Anthony B.↗

NASA NTRS1991

Columbus Programme (current status)

A description is presented for the Columbus Program. The Columbus program comprises a space segment, a ground segment, and operations preparation program, and a utilization preparation program. The space segment consist of three elements: an Attached Pressurized Module (APM); a Man Tended Free Flyer (MTFF); and a Polar platform (PPF). The ground segment is a program shared with other European programs such as Hermes, for communications, services, training and tracking facilities. The Operations preparation program focuses on preparing the ground segment for readiness for the launch of the space segment elements. And the Utilization preparation program includes definition of candidate payload facilities, initial payload selection and precursor flights (Eureca, Spacelab).

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NASA NTRS1989

STS investigators' guide

The capability of the Space Transportation System (STS), the Space Shuttle, to support crew tended and free flyer research in low Earth orbit has opened new possibilities for science in space. For the first time, research equipment can be put into orbit routinely, operated in either a shirtsleeve environment or exposed to space, and then returned to the investigator. NASA, operator of the Shuttle, has implemented a variety of programs to ensure that anyone with a worthy research idea can take advantage of this opportunity. Investigators ranging from high school students to renowned space scientists have already used the Shuttle as a platform for making Earth, atmospheric, and astronomical observations; for performing space plasma physics measurements; and for exploring the effects of microgravity on living organisms and physical processes. For investigators considering a flight experiment for the first time, this guide explains what the Shuttle has to offer, how to arrange to fly an experiment, and what to expect once preparations for the flight are under way.

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NASA NTRS1992

Deployment and retrieval mechanism redesigned for Spartan spacecraft on the STS

The Spartan Release Engage Mechanism (REM) is a system designed to restrain the Spartan spacecraft during Space Transportation System (STS) launch and landing. The mechanism is designed to allow deployment and retrieval of the Spartan free flyer spacecraft from the shuttle payload bay. Because current Spartan spacecraft payloads are much heavier than payloads intended for the original REM, an extensive redesign, analysis, and test program was necessary. Also, increased emphasis on safety in the post-Challenger era prompted a reevaluation of possible failures. Much of the design effort focused on improving the latch mechanism gearbox. Key concerns were effective gear lubrication, thermal gradients at the gearbox mounts, operation at thermal extremes, and gear-train failure contingencies. Increased concern for reliability led to the design of an Extra Vehicular Activity (EVA) backup latch system.

Galloway, Greg↗

NASA NTRS1992

Preliminary total dose measurements on LDEF

After spending nearly six years in Earth's orbit twenty stacks consisting of radiation detectors and biological objects are now back on Earth. These Free Flyer Biostack experiments are part of the Long Duration Exposure Facility (LDEF). The major objective of the experiments are to investigate the biological effectiveness of single heavy ions of the cosmic radiation in various biological systems and to provide information about the spectral composition of the radiation field and the total dose received in the LDEF orbit. The preliminary analysis of the thermoluminescence dosimeters (TLD) yields maximum absorbed dose rates of 2.24 mGy day(exp -1) behind 0.7 g cm(exp -2) shielding and 1.17 mGy day(exp -1) behind 12 g cm(exp -2) shielding. A thermal neutron fluence of 1.7 n cm(exp -2)s(exp -1) is determined from the differences in absorbed dose for different isotopic mixtures of lithium. The results of this experiment on LDEF are especially valuable since LDEF stayed for almost six years in the prospected orbit of the Space Station Freedom.

Reitz, G.↗

NASA NTRS1992

Retrievable payload carrier: Next generation Long Duration Exposure Facility

This paper describes the Retrievable Payload Carrier (RPC), which is a multi-experiment, free flyer spacecraft being privately developed to make in-space experimentation more accessible and economically feasible for research and development organizations. The carrier concept was derived from NASA's highly successful and flight proven Long Duration Exposure Facility (LDEF). The LDEF capabilities have been enhanced to meet new customer requirements. This reusable payload carrier is planned for launch and retrieval by the space shuttle on a regular basis. The RPC's flexible design will facilitate manifesting of the shuttle cargo bay space. The vehicle is designed so that either the entire vehicle or only individual experiments can be removed and replaced. A fully operational RPC program consists of: (1) a carrier spacecraft; (2) a ground control station; (3) a ground processing facility; and (4) the personnel required to support both the development and operational phases of the program.

Perry, Arthur T.↗

NASA NTRS1992

Strategic considerations for support of humans in space and Moon/Mars exploration missions. Life sciences research and technology programs, volume 2

Summary charts of the following topics are presented: the Percentage of Critical Questions in Constrained and Robust Programs; the Executive Committee and AMAC Disposition of Critical Questions for Constrained and Robust Programs; and the Requirements for Ground-based Research and Flight Platforms for Constrained and Robust Programs. Data Tables are also presented and cover the following: critical questions from all Life Sciences Division Discipline Science Plans; critical questions listed by category and criticality; all critical questions which require ground-based research; critical questions that would utilize spacelabs listed by category and criticality; critical questions that would utilize Space Station Freedom (SSF) listed by category and criticality; critical questions that would utilize the SSF Centrifuge; facility listed by category and criticality; critical questions that would utilize a Moon base listed by category and criticality; critical questions that would utilize robotic missions listed by category and criticality; critical questions that would utilize free flyers listed by category and criticality; and critical questions by deliverables.

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NASA NTRS1990

Hand controller commonality evaluation process

A hand controller evaluation process has been developed to determine the appropriate hand controller configurations for supporting remotely controlled devices. These devices include remote manipulator systems (RMS), dexterous robots, and remotely-piloted free flyers. Standard interfaces were developed to evaluate six different hand controllers in three test facilities including dynamic computer simulations, kinematic computer simulations, and physical simulations. The hand controllers under consideration were six degree-of-freedom (DOF) position and rate minimaster and joystick controllers, and three-DOF rate controllers. Task performance data, subjective comments, and anthropometric data obtained during tests were used for controller configuration recommendations to the SSF Program.

Stuart, Mark A.↗

NASA NTRS1991

Designing berthing mechanisms for international compatibility

The paper examines the technological issues regarding common berthing interfaces for the Space Station Freedom and pressurized modules from U.S., European, and Japanese space programs. The development of the common berthing mechanism (CBM) is based on common requirements concerning specifications, launch environments, and the unique requirements of ESA's Man-Tended Free Flyer. The berthing mechanism is composed of an active and a passive half, a remote manipulator system, 4 capture-latch assemblies, 16 structural bolts, and a pressure gage to verify equalization. Extensive graphic and verbal descriptions of each element are presented emphasizing the capture-latch motion and powered-bolt operation. The support systems to complete the interface are listed, and the manufacturing requirements for consistent fabrication are discussed to ensure effective international development.

Winch, John↗