Search NASA⌕ Search

SEARCH · Search NASA

Results for “JET PROPULSION LABORATORY”

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.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Improving software quality - The use of formal inspections at the Jet Propulsion Laboratory

The introduction of software formal inspections (Fagan Inspections) at JPL for finding and fixing defects early in the software development life cycle are reviewed. It is estimated that, by the year 2000, some software efforts will rise to as much as 80 percent of the total. Software problems are especially important at NASA as critical flight software must be error-free. It is shown that formal inspections are particularly effective at finding and removing defects having to do with clarity, correctness, consistency, and completeness. A very significant discovery was that code audits were not as effective at finding defects as code inspections.

Bush, Marilyn↗
NASA NTRS1990

Getting started on metrics - Jet Propulsion Laboratory productivity and quality

A review is presented to describe the effort and difficulties of reconstructing fifteen years of JPL software history. In 1987 the collection and analysis of project data were started with the objective of creating laboratory-wide measures of quality and productivity for software development. As a result of this two-year Software Product Assurance metrics study, a rough measurement foundation for software productivity and software quality, and an order-of-magnitude quantitative baseline for software systems and subsystems are now available.

Bush, M. W.↗
NASA NTRS1991

The NASA Ocean Data System at the Jet Propulsion Laboratory

Global change studies require satellite oceanographic observations archived in an active data center. This paper describes the activities of an experimental active oceanographic data archive center specializing in distribution of high-level oceanographic data products produced by research oceanographers from satellite altimeter, scatterometer, and microwave and infrared radiometer measurements. Methods to encourage data sharing practices were developed. Services initiated to help oceanographers conduct research more effectively included rapid delivery of data, reprocessing data sets, subsetting of large data sets, and distribution of multiple data sets on a single medium.

Halpern, David↗
NASA NTRS1991

Earth observing SAR data processing systems at the Jet Propulsion Laboratory - Seasat to EOS SAR

The evolution of SAR digital data processing and management ground systems developed at the JPL for earth science missions is discussed. Attention is given to the SAR ground data system requirements, the early data processing systems, the Seasat SAR system, and the SIR-B data processing system. Special consideration is given to two currently operational SAR data systems: the JPL aircraft SAR processing system that flies on the NASA DC-8 and the Alaska SAR Facility at Fairbanks.

Nichols, David A.↗
NASA NTRS1993

NASA Center update: Jet Propulsion Laboratory

The topics covered are presented in viewgraph form and include the following: flight project support activities for TOPEX and the Mars Observer; and research/development and engineering activities for NiCd model development, secondary lithium battery development, the sodium-NiCl2 moderate temperature battery, Li-SOCl2 batteries for the Centaur launch vehicle, and direct hydrocarbon/methanol fuel cells.

Distefano, Sal↗
NASA NTRS1992

Architectures for mission control at the Jet Propulsion Laboratory

JPL is currently converting to an innovative control center data system which is a distributed, open architecture for telemetry delivery and which is enabling advancement towards improved automation and operability, as well as new technology, in mission operations at JPL. The scope of mission control within mission operations is examined. The concepts of a mission control center and how operability can affect the design of a control center data system are discussed. Examples of JPL's mission control architecture, data system development, and prototype efforts at the JPL Operations Engineering Laboratory are provided. Strategies for the future of mission control architectures are outlined.

Davidson, Reger A.↗
NASA NTRS1990

The Jet Propulsion Laboratory shared control architecture and implementation

A hardware and software environment for shared control of telerobot task execution has been implemented. Modes of task execution range from fully teleoperated to fully autonomous as well as shared where hand controller inputs from the human operator are mixed with autonomous system inputs in real time. The objective of the shared control environment is to aid the telerobot operator during task execution by merging real-time operator control from hand controllers with autonomous control to simplify task execution for the operator. The operator is the principal command source and can assign as much autonomy for a task as desired. The shared control hardware environment consists of two PUMA 560 robots, two 6-axis force reflecting hand controllers, Universal Motor Controllers for each of the robots and hand controllers, a SUN4 computer, and VME chassis containing 68020 processors and input/output boards. The operator interface for shared control, the User Macro Interface (UMI), is a menu driven interface to design a task and assign the levels of teleoperated and autonomous control. The operator also sets up the system monitor which checks safety limits during task execution. Cartesian-space degrees of freedom for teleoperated and/or autonomous control inputs are selected within UMI as well as the weightings for the teleoperation and autonmous inputs. These are then used during task execution to determine the mix of teleoperation and autonomous inputs. Some of the autonomous control primitives available to the user are Joint-Guarded-Move, Cartesian-Guarded-Move, Move-To-Touch, Pin-Insertion/Removal, Door/Crank-Turn, Bolt-Turn, and Slide. The operator can execute a task using pure teleoperation or mix control execution from the autonomous primitives with teleoperated inputs. Presently the shared control environment supports single arm task execution. Work is presently underway to provide the shared control environment for dual arm control. Teleoperation during shared control is only Cartesian space control and no force-reflection is provided. Force-reflecting teleoperation and joint space operator inputs are planned extensions to the environment.

Backes, Paul G.↗
NASA NTRS1993

The Jet Propulsion Laboratory space exploration - Past, present and future

Attention is given to the most recent scientific results from space exploration carried out by JPL. A brief background of JPL's history is presented, and the Deep Space Network, JPL's system of antennas which communicates with spacecraft, is described. Results from the missions of Voyager 1 and Voyager 2 are discussed. Consideration is given to the atmosphere, rings, satellites, and magnetospheres of Jupiter, Saturn, Uranus, and Neptune. The impact of spray research on space exploration is briefly discussed. An overview of future missions and new NASA policies is also presented.

Bellan, Josette↗
NASA NTRS1994

Re-engineering the Multimission Command System at the Jet Propulsion Laboratory

The Operations Engineering Lab (OEL) at JPL has developed the multimission command system as part of JPL's Advanced Multimission Operations System. The command system provides an advanced multimission environment for secure, concurrent commanding of multiple spacecraft. The command functions include real-time command generation, command translation and radiation, status reporting, some remote control of Deep Space Network antenna functions, and command file management. The mission-independent architecture has allowed easy adaptation to new flight projects and the system currently supports all JPL planetary missions (Voyager, Galileo, Magellan, Ulysses, Mars Pathfinder, and CASSINI). This paper will discuss the design and implementation of the command software, especially trade-offs and lessons learned from practical operational use. The lessons learned have resulted in a re-engineering of the command system, especially in its user interface and new automation capabilities. The redesign has allowed streamlining of command operations with significant improvements in productivity and ease of use. In addition, the new system has provided a command capability that works equally well for real-time operations and within a spacecraft testbed. This paper will also discuss new development work including a multimission command database toolkit, a universal command translator for sequencing and real-time commands, and incorporation of telecommand capabilities for new missions.

Alexander, Scott↗
NASA NTRS1960

Spectral Emittance and Reflectance Measurements at the Jet Propulsion Laboratory

In late 1959 a spectrophotometer laboratory was established at JPL to be used as a support for temperature-control programs. The immediate task was spectroradiometric measurements of light sources to be used in a simulated-deep-space environment chamber. It was also necessary to have permanent provisions for measuring reflectances of surfaces for the calculation of solar absorptance alpha, and thermal emittance epsilon. The spectral distribution of an unknown source, in this case a Ventarc carbon-arc lamp, was derived from the ratio of detector outputs (with monochromatic light) of the arc lamp and a tungsten lamp, and the spectral intensity of the tungsten lamp. The tungsten lamp is a ribbonfilament lamp calibrated from 0.25 to 2.6 microns. A recording of pen deflection (linearly proportional to detector output) of each source over the visible and near infrared range is made with all parameters (slit width, amplifier gain, and source focusing) identical; then the ratios are computed at discrete wavelengths from these recordings. Because the spectral intensities of the tungsten lamp and a solar simulator are very different in most of the range, an adjustable slit is placed immediately in front of the detector to obtain comparable pen deflections for the two sources. This slit is set by means of a feeler gage, and the attenuation coefficient is evaluated by a transmission measurement.

Maclay, James E.↗
NASA NTRS2000

Jet Propulsion Laboratory

Analyses of laser ranges to the Moon are utilized for a broad range of investigations: lunar science, gravitational physics, geodesy, geodynamics and astronomy. Unique contributions from LLR include: detection of a molten lunar core; measurement of tidal dissipation in the Moon; an accurate test of the principle of equivalence for massive bodies (strong equivalence principle); and detection of lunar free librations. LLR analysis has provided tests of relativity, measurements of the Moon's tidal acceleration and the Earth s precession, and has provided orders-of-magnitude improvements in the accuracies of the lunar ephemeris and three-dimensional rotation. JPL has been active in all of these various LLR applications and supplies lunar and planetary ephemerides and lunar physical librations to the community.

Williams, Jim↗