Engineering topics

Derocher, W. L., Jr.

Publications and source records attributed to Derocher, W. L., Jr..

14 records

NASA NTRS1986

Concept definition study for recovery of tumbling satellites. Volume 2: Supporting research and technology report

A number of areas of research and laboratory experiments were identified which could lead to development of a cost efficient remote, disable satellite recovery system. Estimates were planned of disabled satellite motion. A concept is defined as a Tumbling Satellite Recovery kit which includes a modular system, composed of a number of subsystem mechanisms that can be readily integrated into varying combinations. This would enable the user to quickly configure a tailored remote, disabled satellite recovery kit to meet a broad spectrum of potential scenarios. The capability was determined of U.S. Earth based satellite tracking facilities to adequately determine the orientation and motion rates of disabled satellites.

Cable, D. A.↗

NASA NTRS1986

Concept definition study for recovery of tumbling satellites. Volume 1: Executive summary, study results

The first assessment is made of the design requirements and conceptual definition of a front end kit to be transported on the currently defined Orbital Maneuvering Vehicle (OMV) and the Space Transportation System Shuttle Orbiter, to conduct remote, teleoperated recovery of disabled and noncontrollable, tumbling satellites. Previous studies did not quantify the dynamic characteristics of a tumbling satellite, nor did they appear to address the full spectrum of Tumbling Satellite Recovery systems requirements. Both of these aspects are investigated with useful results.

Cable, D. A.↗

NASA NTRS1985

Servicers system demonstration plan and capability development

A plan for the demonstration of the exchange of Multi-Mission Modular Spacecraft (MMS) modules using the servicer mechanism Engineering Test Unit (ETU) was prepared and executed. The plan included: establishment of requirements, conceptual design, selection of MMS spacecraft mockup configuration, selection of MMS module mockup configuration, evaluation of adequacy of ETU load capability, and selection of a stowage rack arrangement. The MMS module exchange demonstration mockup equipment was designed, fabricated, checked out, shipped, installed, and demonstrated.

Bulboaca, M. A.↗

NASA NTRS1984

Spacecraft servicing demonstration plan

A preliminary spacecraft servicing demonstration plan is prepared which leads to a fully verified operational on-orbit servicing system based on the module exchange, refueling, and resupply technologies. The resulting system can be applied at the space station, in low Earth orbit with an orbital maneuvering vehicle (OMV), or be carried with an OMV to geosynchronous orbit by an orbital transfer vehicle. The three phase plan includes ground demonstrations, cargo bay demonstrations, and free flight verifications. The plan emphasizes the exchange of multimission modular spacecraft (MMS) modules which involves space repairable satellites. Three servicer mechanism configurations are the engineering test unit, a protoflight quality unit, and two fully operational units that have been qualified and documented for use in free flight verification activity. The plan balances costs and risks by overlapping study phases, utilizing existing equipment for ground demonstrations, maximizing use of existing MMS equipment, and rental of a spacecraft bus.

Bergonz, F. H.↗

NASA NTRS1979

Computer aided control of a mechanical arm

A method for computer-aided remote control of a six-degree-of-freedom manipulator arm involved in the on-orbit servicing of a spacecraft is presented. The control configuration features a supervisory type of control in which each of the segments of a module exchange trajectory is controlled automatically under human supervision, with manual commands to proceed to the next step and in the event of a failure or undesirable outcome. The implementation of the supervisory system is discussed in terms of necessary onboard and ground- or Orbiter-based hardware and software, and a one-g demonstration system built to allow further investigation of system operation is described. Possible applications of the system include the construction of satellite solar power systems, environmental testing and the control of heliostat solar power stations.

Derocher, W. L., Jr.↗

NASA NTRS1978

Orbital servicing of space platforms

NASA-MSFC is planning systems for the orbital servicing and maintenance of large geosynchronous platforms. The goal is to devise methods to maintain, update, and/or replace the basic spacecraft housekeeping equipment as well as the onboard mission equipment. The planning has passed through the feasibility demonstration level. A hard engineering test unit of such an on-orbit servicing system, complete with control system, is being tested and evaluated by MSFC.

Turner, J. R.↗

NASA NTRS1978

Integrated orbital servicing study follow-on. Volume 1: Executive summary

Orbital maintenance concepts were investigated and the equipment for one-g demonstrations of axial and radial module exchange was designed in three control modes: manual direct control, supervisory control, and manually augmented control. Significant results obtained and the conclusions drawn are presented and discussed. The overall conclusion is that on-orbit servicing should be established as an ongoing space transportation system capability.

Derocher, W. L., Jr.↗

NASA NTRS1978

Calculating parts factors for redundant systems

Method that is easily programmed simplifies calculation of parts factor. Individual module unreliabilities are computed as function of number of service intervals and service interval length. At each service interval, unreliability is sum of unreliabilities of replaced and original modules. It must be calculated for each module to obtain parts factor.

Derocher, W. L., Jr.↗

NASA NTRS1977

Orbital servicing and remotely manned systems

The potential of the concepts and techniques of remotely manned aerospace systems to fully exploit the utility and benefits of orbital servicing is discussed. Orbital servicing has been shown to benefit the Space Transportation System by helping to satisfy spacecraft program objectives of long operating times on-orbit while reducing program costs. The wide range of servicer mechanisms postulated in the literature is reduced to two concepts which are used to generate a set of control system requirements. Three control mode alternatives - automatic, supervisory control, and remotely manned control - are introduced, defined, evaluated and each found wanting in certain areas. A combination of supervisory and remotely manned control is shown to overcome most problems.

Smith, G. W.↗

NASA NTRS1976

Repairing a communications satellite on orbit

A review of past failures indicates that module exchange can satisfy most repair requirements of communications satellites. Emphasis is placed on the design of a serviceable communications satellites with 20 modules, on the development of an on-orbit servicer designed to remove failed modules from a body-stabilized spacecraft and to replace them with good modules, and on servicing operations. Benefits of servicing or repair include increased satellite availability, increased reliability, decreased life cycle costs, replacement of worn-out items, installation of updated equipment, and correction of design failures. The use of servicing instead of replacement could result in cost savings in excess of 40 percent. Significant savings are possible when the lifetime of a program is long relative to the satellite lifetime.

Gordon, G. D.↗

NASA NTRS1975

Integrated orbital servicing study for low-cost payload programs. Volume 1: Executive summary

Various operating methodologies to achieve low-cost space operations were investigated as part of the Space Transportation System (STS) planning. The emphasis was to show that the development investment, initial fleet costs, and supporting facilities for the STS could be effectively offset by exploiting the capabilities of the STS to satisfy mission requirements and reduce the cost of payload programs. The following major conclusions were reached: (1) the development of an on-orbit servicer maintenance system is compatible with many spacecraft programs and is recommended as the most cost-effective system, (2) spacecraft can be designed to be serviceable with acceptable design, weight, volume, and cost effects, (3) use of on-orbit servicing over a 12 year period results in savings ranging between four and nine billion dollars, (4) the pivoting arm on-orbit servicer was selected and a preliminary design was prepared, (5) orbital maintenance has no significant impact on the STS.

Derocher, W. L., Jr.↗

NASA NTRS1975

Integrated orbital servicing study for low-cost payload programs. Volume 2: Technical and cost analysis

Orbital maintenance concepts were examined in an effort to determine a cost effective orbital maintenance system compatible with the space transportation system. An on-orbit servicer maintenance system is recommended as the most cost effective system. A pivoting arm on-orbit servicer was selected and a preliminary design was prepared. It is indicated that orbital maintenance does not have any significant impact on the space transportation system.

Cody, E. R.↗

NASA NTRS1975

The economics of satellite maintenance

The primary goal of the space transportation system - to reduce the cost of space programs while satisfying their mission requirements - can be enhanced by the proper choice of a satellite-maintenance concept. This paper develops the life-cycle costs of performing an automated satellite program during the shuttle era in three competitive modes: expendable, ground-refurbishable, and in-orbit maintainable. In-orbit maintenance is shown to be the most economic maintenance mode for both low- and high-earth orbits.

Derocher, W. L., Jr.↗

NASA NTRS1975

Orbital servicing, and remotely manned systems

The potential of concepts and techniques of remotely manned aerospace systems to fully exploit the utility and benefits of orbital servicing is discussed. Orbital servicing in the form of module exchange enhances the STS goals through replacement of failed equipment, resupply of consumables, and updating of obsolete equipment.

Smith, G. W.↗