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At least 19 records

Aircraft compass characteristics

A description of the test methods used at the National Bureau of Standards for determining the characteristics of aircraft compasses is given. The methods described are particularly applicable to compasses in which mineral oil is used as the damping liquid. Data on the viscosity and density of certain mineral oils used in United States Navy aircraft compasses are presented. Characteristics of Navy aircraft compasses IV to IX and some other compasses are shown for the range of temperatures experienced in flight. Results of flight tests are presented. These results indicate that the characteristic most desired in a steering compass is a short period and, in a check compass, a low overswing.

Peterson, John B

Distributed scheduling with COMPASS

COMPASS (COMPuter Aided Scheduling System) is a sophisticated, interactive scheduling tool used within NASA. Like most existing tools, however, COMPASS is a single-user application. There is a large class of scheduling problems which may be better solved by allowing several people at various locations to build separate schedules with shared resources. DISCORS (DIStributed COmputer Resource Scheduling) is a set of services which support a distributed version of COMPASS. This architecture naturally accommodates the integration of user-defined resource models without modifying COMPASS. DISCORS services include the ability to establish and manage communications, to code messages in efficient formats, to provide fault detection and recovery, and to configure schedulers across a network. In its present form, DISCORS effectively supports distributed COMPASS, but fails to run fast and to guarantee efficient schedules. Further enhancements may allow several users to simultaneously and interactively work together to create complex schedules while COMPASS detects and coordinates the resolution of conflicting requests.

Rufat-Latre, Jorge

The installation and correction of compasses in airplanes

The saving of time that results from flying across country on compass headings is beginning to be widely recognized. At the same time the general use of steel tube fuselages has made a knowledge of compass correction much more necessary than was the case when wooden fuselages were the rule. This paper has been prepared primarily for the benefit of the pilot who has never studied navigation and who does not desire to go into the subject more deeply than to be able to fly compass courses with confidence. It also contains material for the designer who wishes to install his compasses with the expectation that they may be accurately corrected.

COMPASSES

Sun compass error model

An error model is described for the Apollo 15 sun compass, a contingency navigational device. Field test data are presented along with significant results of the test. The errors reported include a random error resulting from tilt in leveling the sun compass, a random error because of observer sighting inaccuracies, a bias error because of mean tilt in compass leveling, a bias error in the sun compass itself, and a bias error because the device is leveled to the local terrain slope.

Blucker, T. J.

COMPASS: A general purpose computer aided scheduling tool

COMPASS is a generic scheduling system developed by McDonnell Douglas under the direction of the Software Technology Branch at JSC. COMPASS is intended to illustrate the latest advances in scheduling technology and provide a basis from which custom scheduling systems can be built. COMPASS was written in Ada to promote readability and to conform to potential NASA Space Station Freedom standards. COMPASS has some unique characteristics that distinguishes it from commercial products. These characteristics are discussed and used to illustrate some differences between scheduling tools.

Mcmahon, Mary Beth

COMPASS: An Ada based scheduler

COMPASS is a generic scheduling system developed by McDonnell Douglas and funded by the Software Technology Branch of NASA Johnson Space Center. The motivation behind COMPASS is to illustrate scheduling technology and provide a basis from which custom scheduling systems can be built. COMPASS was written in Ada to promote readability and to conform to DOD standards. COMPASS has some unique characteristics that distinguishes it from commercial products. This paper discusses these characteristics and uses them to illustrate some differences between scheduling tools.

Mcmahon, Mary Beth

Compact Optoelectronic Compass

A compact optoelectronic sensor unit measures the apparent motion of the Sun across the sky. The data acquired by this chip are processed in an external processor to estimate the relative orientation of the axis of rotation of the Earth. Hence, the combination of this chip and the external processor finds the direction of true North relative to the chip: in other words, the combination acts as a solar compass. If the compass is further combined with a clock, then the combination can be used to establish a threeaxis inertial coordinate system. If, in addition, an auxiliary sensor measures the local vertical direction, then the resulting system can determine the geographic position. This chip and the software used in the processor are based mostly on the same design and operation as those of the unit described in Micro Sun Sensor for Spacecraft (NPO-30867) elsewhere in this issue of NASA Tech Briefs. Like the unit described in that article, this unit includes a small multiple-pinhole camera comprising a micromachined mask containing a rectangular array of microscopic pinholes mounted a short distance in front of an image detector of the active-pixel sensor (APS) type (see figure). Further as in the other unit, the digitized output of the APS in this chip is processed to compute the centroids of the pinhole Sun images on the APS. Then the direction to the Sun, relative to the compass chip, is computed from the positions of the centroids (just like a sundial). In the operation of this chip, one is interested not only in the instantaneous direction to the Sun but also in the apparent path traced out by the direction to the Sun as a result of rotation of the Earth during an observation interval (during which the Sun sensor must remain stationary with respect to the Earth). The apparent path of the Sun across the sky is projected on a sphere. The axis of rotation of the Earth lies at the center of the projected circle on the sphere surface. Hence, true North (not magnetic North), relative to the chip, can be estimated from paths of the Sun images across the APS. In a test, this solar compass has been found to yield a coarse estimate of the North (within tens of degrees) in an observation time of about ten minutes. As expected, the accuracy was found to increase with observation time: after a few hours, the estimated direction of the rotation axis becomes accurate to within a small fraction of a degree.

Christian, Carl

Compass Concurrent Engineering Lessons Learned in Remote and Hybrid Environments

The Compass Team at NASA’s Glenn Research Center (GRC) is a concurrent engineering team which specializes in conceptual spacecraft mission designs. Detailed descriptions of the team, its history, and its operating model can be found in [1] and [2]. During the COVID-19 pandemic, the team was required to move to remote (virtual) operation from their in-person model for approximately 22 months. As the restrictions began to lift and team members were able to return in-person to the Compass Lab, the team moved into a hybrid mode of operation, with some participants still tying in remotely some or all of the time. This paper discusses many of the lessons learned from these experiences, highlighting improvements, outstanding challenges and the tools and methodologies used to address both. Throughout this discussion the terms “in-person”, “hybrid”, “virtual” and “remote” will be used. For the purposes of this paper, “in-person” will be understood to mean when team members are interacting simultaneously, physically within the Compass Lab. “Remote” or “virtual” will refer to when interactions are happening between people who are not co-located using only technology to interface. “Hybrid” will refer to when two or more participants are physically located in the Compass Lab and one or more participant(s) is participating remotely. Media richness is described as “a medium’s ability to communicate effectively based of four factors. They are the capacity for immediate feedback, the number of cues and channels it utilizes, the degree of personalization it affords, and its ability to communicate using natural language” [3]. This theory will be referenced and discussed in multiple of the following sections due to its relevance when choosing how to operate in remote and hybrid modes, as well as in making tool selections. The key to selecting the best mode of communication lays in how complicated the discussion is and the level of ambiguity involved. Not all conversations or interactions require media rich mediums. For example, providing information about which there is little to no ambiguity can easily be done in less rich methods - such as email. A conversation including high levels of ambiguity and/or complex information is better suited to a richer medium, such as in-person or a video call with shared screens.

Concurrent Engineering

Resource representation in COMPASS

A set of viewgraphs on resource representation in COMPASS is given. COMPASS is an incremental, interactive, non-chronological scheduler written in Ada with an X-windows user interface. Beginning with an empty schedule, activities are added to the schedule one at a time, taking into consideration the placement of the activities already on the timeline and the resources that have been reserved for them. The order that the activities are added to the timeline and their location on the timeline are controlled by selection and placement commands invoked by the user. The order that activities are added to the timeline and their location are independent. The COMPASS code library is a cost effective platform for the development of new scheduling applications. It can be effectively used off the shelf for compatible scheduling applications or it can be used as a parts library for the development of custom scheduling systems.

Fox, Barry R.

Concurrent Mission and Systems Design at NASA Glenn Research Center: The Origins of the COMPASS Team

Established at the NASA Glenn Research Center (GRC) in 2006 to meet the need for rapid mission analysis and multi-disciplinary systems design for in-space and human missions, the Collaborative Modeling for Parametric Assessment of Space Systems (COMPASS) team is a multidisciplinary, concurrent engineering group whose primary purpose is to perform integrated systems analysis, but it is also capable of designing any system that involves one or more of the disciplines present in the team. The authors were involved in the development of the COMPASS team and its design process, and are continuously making refinements and enhancements. The team was unofficially started in the early 2000s as part of the distributed team known as Team JIMO (Jupiter Icy Moons Orbiter) in support of the multi-center collaborative JIMO spacecraft design during Project Prometheus. This paper documents the origins of a concurrent mission and systems design team at GRC and how it evolved into the COMPASS team, including defining the process, gathering the team and tools, building the facility, and performing studies.

McGuire, Melissa L.

Estimation Model of Spacecraft Parameters and Cost Based on a Statistical Analysis of COMPASS Designs

The Collaborative Modeling for Parametric Assessment of Space Systems (COMPASS) team at Glenn Research Center has performed integrated system analysis of conceptual spacecraft mission designs since 2006 using a multidisciplinary concurrent engineering process. The set of completed designs was archived in a database, to allow for the study of relationships between design parameters. Although COMPASS uses a parametric spacecraft costing model, this research investigated the possibility of using a top-down approach to rapidly estimate the overall vehicle costs. This paper presents the relationships between significant design variables, including breakdowns of dry mass, wet mass, and cost. It also develops a model for a broad estimate of these parameters through basic mission characteristics, including the target location distance, the payload mass, the duration, the delta-v requirement, and the type of mission, propulsion, and electrical power. Finally, this paper examines the accuracy of this model in regards to past COMPASS designs, with an assessment of outlying spacecraft, and compares the results to historical data of completed NASA missions.

cost modeling

Parallel-End-Point Drafting Compass

Parallelogram linkage ensures greater accuracy in drafting and scribing. Two members of arm of compass remain parallel for all angles pair makes with hub axis. They maintain opposing end members in parallelism. Parallelogram-linkage principle used on dividers as well as on compasses.

Cronander, J.

COMPASS Final Report: Lunar Relay Satellite (LRS)

The Lunar Relay Satellite (LRS) COllaborative Modeling and Parametric Assessment of Space Systems (COMPASS) session was tasked to design a satellite to orbit in an elliptical lunar polar orbit to provide relay communications between lunar South Pole assets and the Earth. The design included a complete master equipment list, power requirement list, configuration design, and brief risk assessment and cost analysis. The LRS is a half-TDRSS sized box spacecraft, which provides communications and navigation relay between lunar outposts (via Lunar Communications Terminals (LCT)) or Sortie parties (with user radios) and large ground antennas on Earth. The LRS consists of a spacecraft containing all the communications and avionics equipment designed by NASA Jet Propulsion Laboratory s (JPL) Team X to perform the relay between lunar-based assets and the Earth. The satellite design is a standard box truss spacecraft design with a thermal control system, 1.7 m solar arrays for 1 kWe power, a 1 m diameter Ka/S band dish which provides relay communications with the LCT, and a Q-band dish for communications to/from the Earth based assets. While JPL's Team X and Goddard Space Flight Center s (GSFC) I M Design Center (IMDC) have completed two other LRS designs, this NASA Glenn Research Center (GRC) COMPASS LRS design sits between them in terms of physical size and capabilities.

Oleson, Steven R.

Compass Final Report: Europa Tunnelbot

The Compass Final Report: Europa Tunnelbot, is a summary of three Compass concurrent engineering team designs for penetrating the ice of Europa and reaching the ocean, while sampling for biomarkers and communicating back to the surface. These conceptual designs, while providing complete conceptual layouts for these penetrators, or 'Tunnelbots' along with the associated communication 'Repeaters' primarily focused on the power and thermal systems needed for these devices. Trades for these systems will provide advantages and challenges for each option. These results will be used to guide power technology development.

probe

Lessons Learned in Concurrent Mission and Systems Design at NASA Glenn Research Center: Almost Fifteen Years of the Compass Team

This paper is a retrospective of the lessons learned during the almost 15-year history of the Compass concurrent mission and systems design team at NASA’s Glenn Research Center (GRC). It examines the key factors in the team’s evolution from a temporary group gathered to perform a single study to the successful, sustainable team it is today. Compass is a matrixed team of experts with various technical backgrounds and personalities. They collaborate over a two-week period either physically in a dedicated meeting space, or virtually to design a space system (Spacecraft, stage, science package, etc). Over the years, because of the rapid nature of the design studies, the team leadership has iterated on the optimal team member personality makeup, facility elements and tools as well as NASA GRC management support necessary to lead to sustained success.

systems engineering

COMPASS Final Report: 2008 International Lunar Network (ILN)

The Compass team developed three designs for a soft lander for the International Lunar Network (ILN) using different power systems. These systems included solar arrays and batteries and two radioisotope power system (RPS) options scaled down from previous designs. These are a half Stirling radioisotope generator and a one-eighth Radioisotope Thermoelectric Generator (RTG). The COMPASS design consists of a soft-lander capable of network science (seismic, magnetospheric, laser reflector, and thermal transfer) that can land anywhere on the near side of the Moon and operate for at least six years. The baseline version, using only batteries and solar arrays, requires a very large battery (~80 kg) for the roughly 20 W night-time power requirements. The lander launch mass (with solid rocket breaking motor) is almost 900 kg. With such a large battery, the lander will require a launcher larger than the desired Minotaur V; a Taurus II (being developed for NASA Commercial Orbital Transportation Services (COTS)) or larger (Delta II or Atlas V) would be needed. The two RPS cases, half an Advanced Stirling Radioisotope Generators (ASRG) and one-eighth RTG have much smaller launch masses of 500 and 600 kg respectively. (The one-eighth RTG case lacks the power for the full science package, so a solar array battery is still needed.) Unfortunately, the Minotaur V’s launch capability is still not large enough (~430 kg to trans-lunar injection (TLI)) for the RPS systems. Consequently, a fourth case was developed to fly a limited science floor suite of instruments (seismometer only) which reduced the RPS Lander launch mass to fit on a Minotaur V.

Radioisotope Power Systems

Real Sky Performance of the Prototype sted Advanced Stellar Compass

The Danish microsatellite, sted, is equipped with an autonomous, advanced stellar compass (ASC). The ASC consists of two separate units, a Charge Coupled Device (CCD) camera head (based on a commercial Sony interline CCD detector) and a data processing unit with a powerful microcomputer (Intel 80486 type processor). The microcomputer memory contains a star catalogue which enables the microcomputer to recognize the constellations of stars in the field of vies and thus derive the attitude of the ASC camera head. The mission, and the design, operation and performance of the ASC are described. Results of the ASC prototype tests at the Jet Propulsion Laboratory (JPL) Table Mountain Observatory (TMO) facility are given.

orstedautonomous advanced stellar compass ASC adva

Astronomical Performance of the Engineering Model rsted Advanced Steller Compass

The Danish geomagnetic microsatellite, rsted, is an autonomous sciencecraft which is scheduled for a May 1997 launch into polar orbit. It is produced by a consortium of universities, industry, and government and is Denmark's first national spacecraft. NASA support includes JPL real sky evaluation of its star tracker, the Advanced Stellar Compass (ASC).

mission