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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 253 records · Page 14

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NASA NTRS1986

An investigation of selected on-orbit satellite servicing issues

The results of three separate investigations performed by Science Applications International Corporation (SAIC) between August 1985 and October 1986 as the second phase of the two-phase Satellite Services System Program Plan contract for the Engineering Directorate of the Lyndon B. Johnson Space Center are discussed. The objectives of the first phase of this contract (reported in SAIC-85/1762) were to determine the potential for servicing a diverse range of spacecraft from the Space Shuttle Orbiter and to assess NASA's role as the catalyst in enabling routine on-orbit servicing. The second area of investigation was prompted by the need to understand satellite servicing requirements in the far term (1995 to 2010) and how results from the first phase of this contract could support these requirements. The mission model developed during the first phase was extended using new data and information from studies which address the later time period. The third area of investigation looked at a new servicing mode which had not been studied previously. This mode involves the on-orbit exchange of very large modules with masses greater than approximately 9,000 kilograms and/or lengths greater than approximately nine meters. The viewgraphs used for the final briefing for each of the three investigations, as presented to NASA are given.

Hoffman, Stephen J.↗

NASA NTRS1987

Servicing operations for the SIRTF Observatory at the Space Station

This paper describes the servicing requirements, plans, and proposed Space Station-based servicing operations for the Space Infrared Telescope Facility (SIRTF) Observatory. SIRTF is a cryogenically-cooled, long-life, one meter class space telescope which will be operated by NASA as a free-flying observatory for infrared astronomy, in the mid-1990's. To achieve its 5-year lifetime requirement (10 year goal), SIRTF must be replenished periodically with cryogenic helium and have its life-limited modular subsystems replaced; capability for contingency repair of warm components will also be provided in the Observatory design. A general description of the SIRTF Observatory is given, including options for the support systems (spacecraft). The overall servicing philosophy and plans are addressed with scheduling and needed support elements described. A proposed Space Station-based servicing scenario is described, including orbital transfer, servicing and checkout operations. A detailed description and timeline for liquid helium replenishment operations is provided, including a conceptual design and technology development program for the cryogenic helium transfer dewar (tanker). Finally, a preliminary SIRTF spares/logistics philosophy is outlined, including tradeoffs to be considered.

Wiltsee, Christopher B.↗

NASA NTRS1987

Servicer system demonstration plan and capability development

An orbital maneuvering vehicle (OMV) front end kit is defined which is capable of performing in-situ fluid resupply and modular maintenance of free flying spacecraft based on the integrated orbital servicing system (IOSS) concept. The compatibility of the IOSS to perform gas and fluid umbilical connect and disconnect functions utilizing connect systems currently available or in development is addressed. A series of tasks involving on-orbit servicing and the engineering test unit (ETU) of the on-orbit service were studied. The objective is the advancement of orbital servicing by expanding the Spacecraft Servicing Demonstration Plan (SSDP) to include detail demonstration planning using the Multimission Modular Spacecraft (MMS) and upgrading the ETU control.

Source record↗

NASA NTRS1988

Design guidelines for robotically serviceable hardware

Research being conducted at the Goddard Space Flight Center into the development of guidelines for the design of robotically serviceable spaceflight hardware is described. A mock-up was built based on an existing spaceflight system demonstrating how these guidelines can be applied to actual hardware. The report examines the basic servicing philosophy being studied and how this philosophy is reflected in the formulation of design guidelines for robotic servicing. A description of the mock-up is presented with emphasis on the design features that make it robot friendly. Three robotic servicing schemes fulfilling the design guidelines were developed for the mock-up. These servicing schemes are examined as to how their implementation was affected by the constraints of the spacecraft system on which the mock-up is based.

Gordon, Scott A.↗

NASA NTRS1987

Satellite servicing in the Space Station era

The paper examines the lessons learned from past experiences, the requirements that apply to the various types of missions requiring servicing, and the present plans for establishing a system by which on-orbit servicing, assembly, and repair will become routine. It is noted that, by expanding on the servicing experience and capabilities provided directly by the STS, the Space Station will significantly enhance the mission objectives of long-duration scientific missions, not only by repair and consumable replenishment, but also by the addition and replacement of scientific instruments with upgraded versions. The servicing facility design is described, and a typical servicing scenario is presented.

Lavigna, Thomas A.↗

NASA NTRS1987

Technology advancements for servicing of future spacecraft systems

Problems associated with the in-orbit repair and maintenance of spacecraft systems are examined with reference to experience gained from three servicing missions: in-orbit capture, repair, and reflight of the Solar Maximum Mission satellite, capture and return to earth of the Palapa and Westar communications satellites, and in-orbit repair of Syncom 3. It is then shown how the lessons learned from the three servicing missions are applied to current and future servicing activities. In particular, planned servicing missions for the Hubble Space Telescope, tools and servicing facilities development, and the development of the Explorer Platform are discussed.

Cepollina, F. J.↗

NASA NTRS1989

Advanced information processing system: Local system services

The Advanced Information Processing System (AIPS) is a multi-computer architecture composed of hardware and software building blocks that can be configured to meet a broad range of application requirements. The hardware building blocks are fault-tolerant, general-purpose computers, fault-and damage-tolerant networks (both computer and input/output), and interfaces between the networks and the computers. The software building blocks are the major software functions: local system services, input/output, system services, inter-computer system services, and the system manager. The foundation of the local system services is an operating system with the functions required for a traditional real-time multi-tasking computer, such as task scheduling, inter-task communication, memory management, interrupt handling, and time maintenance. Resting on this foundation are the redundancy management functions necessary in a redundant computer and the status reporting functions required for an operator interface. The functional requirements, functional design and detailed specifications for all the local system services are documented.

Burkhardt, Laura↗

NASA NTRS1989

AdaNET services

MountainNet is a small firm which serves as a distribution center for AdaNET Services. These services include providing host systems and telecommunications for AdaNET, developing and supporting AdaNET Information Services, and developing a dynamic software inventory. AdaNET hosts are a Data General MV8000II and DEC VAX. Telecommunications are provided via the MountainNet private network and the Telenet public access dial network. Initially, the AdaNET Information Services will include software repositories, user communications and forums, software engineering information, bibliographic and library services, and an educational directory. The dynamic software inventory, which will become available in January 1990, will contain software engineering code and parts.

Digman, Michael↗

NASA NTRS1989

Hierarchy of on-orbit servicing interfaces

A series of equipment interfaces is involved in on-orbit servicing operations. The end-to-end hierarchy of servicing interfaces is presented. The interface concepts presented include structure and handling, and formats for transfer of resources (power, data, fluids, etc.). Consequences on cost, performance, and service ability of the use of standard designs or unique designs with interface adapters are discussed. Implications of the interface designs compatibility with remote servicing using telerobotic servicers are discussed.

Moe, Rud V.↗

NASA NTRS1989

An Earth Orbiting Satellite Service and Repair Facility

A conceptual design was produced for the Geosynchronous Satellite Servicing Platform (GSSP), an orbital facility capable of repairing and servicing satellites in geosynchronous orbit. The GSSP is a man-tended platform, which consists of a habitation module, operations module, service bay and truss assembly. This design review includes an analysis of life support systems, thermal and power requirements, robotic and automated systems, control methods and navigation, and communications systems. The GSSP will utilize existing technology available at the time of construction, focusing mainly on modifying and integrating existing systems. The entire facility, along with two satellite retrieval vehicles (SRV), will be placed in geosynchronous orbit by the Advanced Launch System. The SRV will be used to ferry satellites to and from the GSSP. Technicians will be transferred from Earth to the GSSP and back in an Apollo-derived Crew Transfer Capsule (CTC). These missions will use advanced telerobotic equipment to inspect and service satellites. Four of these missions are tentatively scheduled per year. At this rate, the GSSP will service over 650 satelites during the projected 25 year lifespan.

Berndt, Andrew↗

NASA NTRS1989

A FD/DAMA network architecture for the first generation land mobile satellite services

A frequency division/demand assigned multiple access (FD/DAMA) network architecture for the first-generation land mobile satellite services is presented. Rationales and technical approaches are described. In this architecture, each mobile subscriber must follow a channel access protocol to make a service request to the network management center before transmission for either open-end or closed-end services. Open-end service requests will be processed on a blocked call cleared basis, while closed-end requests will be processed on a first-come-first-served basis. Two channel access protocols are investigated, namely, a recently proposed multiple channel collision resolution scheme which provides a significantly higher useful throughput, and the traditional slotted Aloha scheme. The number of channels allocated for either open-end or closed-end services can be adaptively changed according to aggregated traffic requests. Both theoretical and simulation results are presented. Theoretical results have been verified by simulation on the JPL network testbed.

Yan, T.-Y.↗

NASA NTRS1992

Practical theories for service life prediction of critical aerospace structural components

A new second-order theory was developed for predicting the service lives of aerospace structural components. The predictions based on this new theory were compared with those based on the Ko first-order theory and the classical theory of service life predictions. The new theory gives very accurate service life predictions. An equivalent constant-amplitude stress cycle method was proposed for representing the random load spectrum for crack growth calculations. This method predicts the most conservative service life. The proposed use of minimum detectable crack size, instead of proof load established crack size as an initial crack size for crack growth calculations, could give a more realistic service life.

Ko, William L.↗

NASA NTRS1990

System considerations, projected requirements and applications for aeronautical mobile satellite communications for air traffic services

The projected application and requirements in the near term (to 1995) and far term (to 2010) for aeronautical mobile services supporting air traffic control operations are addressed. The implications of these requirements on spectrum needs, and the resulting effects on the satellite design and operation are discussed. The U.S. is working with international standards and regulatory organizations to develop the necessary aviation standards, signalling protocols, and implementation methods. In the provision of aeronautical safety services, a number of critical issues were identified, including system reliability and availability, access time, channel restoration time, interoperability, pre-emption techniques, and the system network interfaces. Means for accomplishing these critical services in the aeronautical mobile satellite service (AMSS), and the various activities relating to the future provision of aeronautical safety services are addressed.

Mcdonald, K. D.↗

NASA NTRS1991

Broadcast satellite service: The international dimension

The dawn of the 1990's has witnessed the birth of a new satellite service - satellite sound broadcasting. This new service is characterized by digital transmission at data rates up to 256 kb/s from satellites in geostationary orbit to small, low-cost, mobile and portable receivers. The satellite sound broadcasting service is a logical step beyond navigation satellite service, such as that provided by the GPS Navstar system. The mass market appeal of satellite sound broadcasting in the area of lightsat technology and low-cost digital radios has greatly facilitated the financing of this type of space service.

Samara, Noah↗

NASA NTRS1992

User services in the TDRS II era

The next generation Tracking and Data Relay Satellite System (TDRS II) will provide a new level of telemetry, tracking and command services to user spacecraft. In addition to the S-band and Ku-band services, which have made the Space Network concept a reality, a new multifrequency dual-polarization high data rate Ka-band service will also be provided. The S-band multiple-access system will have a larger number of phased array elements, on-board beam forming, and a receive capability equivalent to a single-access antenna. A multifunctional intersatellite link, capable of relaying between TDRS IIs and providing an additional single-access service, is also planned. Enhancements, which include an improved location capability for both the TDRS II and user satellite, a navigation beacon, and a real-time emergency command capability will also be part of the TDRS II. The TDRS II will be three-axis stabilized sufficiently to provide these services to users either on the ground, in low earth orbit, or out to geosynchronous orbit.

Comberiate, Anthony B.↗

NASA NTRS1993

Transparent data service with multiple wireless access

The rapid introduction of digital wireless networks is an important part of the emerging digital communications scene. The introduction of Digital Cellular, LEO and GEO Satellites, and Personal Communications Services poses both a challenge and an opportunity for the data user. On the one hand wireless access will introduce significant new portable data services such as personal notebooks, paging, E-mail, and fax that will put the information age in the user's pocket. On the other hand the challenge of creating a seamless and transparent environment for the user in multiple access environments and across multiple network connections is formidable. A summary of the issues associated with developing techniques and standards that can support transparent and seamless data services is presented. The introduction of data services into the radio world represents a unique mix of RF channel problems, data protocol issues, and network issues. These problems require that experts from each of these disciplines fuse the individual technologies to support these services.

Dean, Richard A.↗

NASA NTRS1994

Graphical programming: A systems approach for telerobotic servicing of space assets

Satellite servicing is in many ways analogous to subsea robotic servicing in the late 1970's. A cost effective, reliable, telerobotic capability had to be demonstrated before the oil companies invested money in deep water robot serviceable production facilities. In the same sense, aeronautic engineers will not design satellites for telerobotic servicing until such a quantifiable capability has been demonstrated. New space servicing systems will be markedly different than existing space robot systems. Past space manipulator systems, including the Space Shuttle's robot arm, have used master/slave technologies with poor fidelity, slow operating speeds and most importantly, in-orbit human operators. In contrast, new systems will be capable of precision operations, conducted at higher rates of speed, and be commanded via ground-control communication links. Challenge presented by this environment include achieving a mandated level of robustness and dependability, radiation hardening, minimum weight and power consumption, and a system which accommodates the inherent communication delay between the ground station and the satellite. There is also a need for a user interface which is easy to use, ensures collision free motions, and is capable of adjusting to an unknown workcell (for repair operations the condition of the satellite may not be known in advance). This paper describes the novel technologies required to deliver such a capability.

Pinkerton, James T.↗

NASA NTRS1993

MOOSE: Manned On-Orbit Servicing Equipment

The ability to service satellites has thus far been limited to low earth orbit platforms within reach of the Space Shuttle. Other orbits, such as geosynchronous orbits containing high-value spacecraft have not been attainable by a servicing vehicle. The useful life of a satellite can be extended by replacing spent propellant and damaged orbital replacement units, forestalling the need for eventual replacement. This growing need for satellite on-orbits servicing can be met by the Manned On-Orbit Servicing Equipment (MOOSE). Missions requiring orbit transfer capability, precision manipulation and maneuvering, and man-in-the-loop control can be accomplished using MOOSE. MOOSE is a flexible, reusable, single operator, aerobraking spacecraft designed to refuel, repair, and service orbiting spacecraft. MOOSE will be deployed from Space Station Freedom, (SSF), where it will be stored, resupplied, and refurbished.

Budinoff, J.↗