NASA Projects Research Articles

Computational General Relativistic Astrophysics: The Neutron Star Grand Challenge Project

General Relativistic Astrophysics — astrophysics that involves strong and dynamical gravitational fields requiring the full Einstein equations for its understanding — is becoming an exciting area of research, due to the large amount of data in high energy astronomy, and to the great promise of gravitational wave astronomy. In particular, Computational General Relativistic Astrophysics, with the recent stunning increases in computer power, may hold the key to the understanding of many observations in high energy astronomy and gravitational wave astronomy. The NASA Neutron Star Grand Challenge Project aims at developing a computational infrastructure for general relativistic astrophysics based on state-of-the-art massively parallel computational technology. The numerical simulation of coalescing neutron stars was chosen as the driving application of the code development effort. In this paper we review the present status of the project. The 3D code that contains the Einstein equations and the relativistic hydrodynamic equations has recently passed the final milestone requirement of the NASA project and has been released to the community with documentation. We propose a set of testing criteria for the validation of general relativistic hydrodynamic codes, and discuss some preliminary results obtained with the code on the head-on collisions of neutron stars.

Chain of Errors Hurled Probe Into Spin

SPACE SCIENCEThe loss of the $1 billion Solar and Heliospheric Observatory (SOHO), a joint project of NASA and the European Space Agency, has exposed a long chain of software and control errors, a NASA review panel has found. The report says a pair of software bugs laid the groundwork for a disastrous command from controllers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, which caused SOHO to spin out of control early on 25 June. Science has learned that the debacle also revealed other foul-ups, which played smaller roles in the loss.

Particle concentration characterization for jet engine emissions under cruise conditions

Airborne particle measurements during NASA project SUCCESS have shown that particle concentration profiles serve as good indicators of aircraft exhaust plume encounters. During exhaust plume penetrations there is a strong anticorrelation between the ratio of nonvolatile/total particulates and Nitrogen Oxide (NO) concentrations. An increase in fuel sulfur content was found to increase the total particle emission index, while the nonvolatile emission index remained unchanged. The EI's increased by a factor of 2.6 as the fuel sulfur increased from 70–700 ppm. The large particle size distribution (200–400 nm) was seen as a good long term indicator of an aircraft exhaust plume.

Web-based issue tracking for large software projects

Many problems are found and fixed during the development of a software system. The Project Issue Tracking System toolkit, a Web-based issue-management tool, can be used to organize issue reports during development and to communicate with different project teams around the world. The Project Issue Tracking System (PITS) is a tool that supports the IV&V effort for two major NASA projects: the Earth Observation System Data and Information System (EOSDIS) and the Earth Science Data and Information System (ESDIS). The EOSDIS IV&V effort teams several companies and organizations at several sites with Intermetrics, Inc, serving as the lead contractor. We examine the PITS Web-based mechanisms for tracking issue reports.

Journey's end

Nineteen years and five broken gyroscopes after its launch, the International Ultraviolet Explorer (IUE) was finally decommissioned on September 30. The shutdown of IUE marked the end of what NASA officials called one of “the longest and most productive missions in the history of space science.” IUE was a joint project of NASA, the European Space Agency, and the Particle Physics and Astronomy Research Council (United Kingdom).Designed to last just 3 years, IUE operated for about 24 hours a day from a geosynchronous orbit for nearly two decades. The observatory and spectrographic instruments enabled studies of phenomena that emit ultraviolet radiation, and the results were prodigious.

Safety and mission assurance in a better, faster, cheaper environment

To provide the American people with an exciting aeronautics and space program that provides more tangible value in products and services and more relevance to the public, NASA has developed a philosophy that emphasizes better, faster, and cheaper ways of conducting business. The integration of safety, reliability and quality assurance (SR&QA) products and services into all NASA's programs and projects, from beginning to end, and the implementation of progressive quality management and contracting practices are direct applications of this philosophy. NASA's new test effectiveness program integrates the oribital performance and reliability experience of prior spacecraft with new design processes and improved telemetry to achieve higher performance and reliability, faster, and at reduced cost. As United States government leaders for ISO 9000 implementation, NASA is promoting single quality systems for contractors, the use of advanced quality practices, and methods for the implementation of baseline quality systems with the appropriate oversight to further low cost, high performance programs in the future. To remain vital in today's era of fiscal constraint, NASA must be efficient, effective, and relevant. The innovative integration and application of SR&QA tools, techniques, and management approaches in all NASA's programs and projects will play an integral role in achieving this end.

A progress report on the NASA orbital debris handbook

Abstract To implement the NASA policy to limit the generation of orbital debris for NASA space missions as stated in NASA Management Instruction 1700.8, NASA has sponsored the development of a handbook to provide guidelines and analysis tools for use by NASA Program and Project managers. This handbook has been discussed in other papers/1,2/. In the last 8 months the handbook has been subject to two reviews within NASA. In December, 1993, comments were received from a general review of the handbook and guidelines. The document was modified and sent out for detailed technical review in June, 1994. In this paper the concerns raised during the review process will be discussed and the current form of the handbook guidelines and support documentation will described.

The Deforestation Debate

While tropical forests are vanishing at a disturbing rate, the wide-spread disagreement over deforestation estimates makes it difficult for government officials and scientists to assess the problem. In turn this hampers efforts to gauge the threat of related issues such as habitat destruction and global warming. Creating more confusion is the realization that partly deforested, but not stripped, lands have not been completely taken into account. In addition lands in tropical regions but outside the tropical rain forest are poorly represented. This article uses Brazil as an example of the conflicting estimates. The efforts of the United Nations Food and Agriculture Organization (FAO) to improve its estimates are described. An on-going NASA project to help is also described.

NASA town meetings scheduled

The dates and locations for a series of public town meetings sponsored by NASA have been set. The meetings will give the public a chance to learn about NASA's projects and to express their opinions on aspects of the space program, according to NASA Administrator Daniel S. Goldin. Presentations at the town meetings will be made by top NASA officials, university researchers, members of the business community, educators, and individuals from aerospace associations. The public will be able to ask questions.Each of the town meetings will be held from 2:00 to 6:30 P.M. local time. Dates and locations are listed below.

Real-time software failure characterization

A series of studies aimed at characterizing the fundamentals of the software failure process has been undertaken as part of a NASA project on the modeling of a real-time aerospace vehicle software reliability. An overview of these studies is provided, and the current study, an investigation of the reliability of aerospace vehicle guidance and control software, is examined. The study approach provides for the collection of life-cycle process data, and for the retention and evaluation of interim software life-cycle products.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Next-generation spacecraft control

A description is given of some advanced spacecraft control applications. The Gamma Ray Observatory (GRO) has decision-making software that gives each of its instruments some discretion as to what it observes, as well as a local area network over which one instrument can alert the rest to a special event. The Hubble Space Telescope, a joint project of NASA and the European Space Agency, relies on artificial intelligence in ground-based software to schedule when it is to view some object, while onboard control systems let it find and track targets with a precision finer than systems on earth. In the probe the Galileo spacecraft will release into Jupiter's atmosphere, the electronics are engineered to survive forces up to 350 times the Earth's gravity and heat as great as on the Sun's surface. >

Introduction

Abstract It is a pleasure to be introducing this symposium to provide an appreciation of the real interest that NASA has in using plant systems for life support in space. The symposium is directed toward providing details on what is planned, and what is actually underway, in this effort. It is a program that has been titled CELSS, Controlled Ecological Life Support System, and involves a tremendous breadth of horticultural areas—areas that can require the expertise of nearly everyone in horticulture, as suggested in Fig. 1. The project must start with plant propagation, probably tissue culture propagation, and involve all aspects of environmental optimization of growth, breeding of adapted cultivars, nutrient, possibly nutrient film, feeding techniques (NFT) and automated nutrient recycling, contaminant control in the atmosphere, pathogen control in the nutrient solution, precise growth modeling for regulation of the system, maximization of harvest index to reduce inedible portions, efficient food processing, balanced diets, and complete recycling of all wastes. The expertise of all types of horticulturists is needeed if this project of NASA is to be successful.

A Highly Reliable LAN Protocol

As a research project for NASA's Langley Research Center, we developed a variation on MIL-STD-1553B (the military standard for avionics buses) whose goal was increased fault tolerance. The resulting protocol, called implicit passing (ITP), replaces an explicit with brief soundoff messages from all nodes participating on the LAN. Since every node participates on every token cycle, bus silence is an error indication and initiates recovery action. By encoding state information in the headers of the transmitted words, nodes are continuously aware of the global state of the network. This local knowledge of the global network state allows the system to continue operation in spite of nodal failures. A station which fails but then recovers can quickly assess the global network state and then safely rejoin the active nodes. ITP features high throughput and bounded message delay, and achieves high reliability through tolerance of failed nodes and automatic resynchronization when failed nodes are revived. The protocol is ideally suited for a bus topology and fiber optic media.

Dual-Doppler Lidar Measurement of Winds in the JAWS Experiment

The use of coherent Doppler lidar measurements for analysis of wind fields near airports was investigated during the Joint Airport Weather Studies (JAWS) project of NASA and NOAA. Periodic lidar scans were made with two 10.6-micron CO2-pulsed Doppler lidars spaced 15 km apart in order to calculate the Cartesian wind fields near Marshall Space Flight Center (MSFC). Analyses were also carried out for the flow behind gust fronts, with the desired flow fields corresponding both to surface winds measured by a Portable Automated Mesonet (PAM), and numerical models of Great Plains thunderstorm outflows. Comparison of low elevation scans carried out using the lidar instruments and a CP-4 Doppler radar showed distinct differences due to a bias toward weaker velocities in the radar measurements. The rms difference between the radar and the lidar measurements was 3.1 m/s. The experimental results were consistent with those of a previous study comparing Wave Propagation Laboratory (WPL) lidar with the CP-3 5.5-cm radar operated by the National Center for Atmospheric Research (NCAR).

Making new things happen: an interpretation of observed innovation strategies

Innovation although variously defined is a process whereby individuals discover and implement the means for meeting environmental needs. An examination of various innovation projects reveals three overlapping approaches. Provisionally, these approaches have been described as 1. Mission Oriented or Contractual 2. Integrative or Negotiative 3. Participative Examples of mission oriented approaches come from projects with a strong emphasis on technological factors, and are often characterised by well-defined technical targets or objectives. The NASA projects of the 1960s–1970s were large scale examples of the approach. Contract Research laboratories provide many other examples. Integrative approaches seek to reconcile potentially conflicting factors within the change process. Sociotechnical systems do this by integrating technical and social needs. Participative approaches draw heavily from the Action Research paradigm, and achieve innovative change as a process of social learning. Quality Circles, action learning (Revans), Joint Development Activities (John Morris) are well-known examples of the participative approach. The nature of these approaches is discussed and some practical and theoretical problems are looked at. How should advocates of participative approaches deal with requests for “proof” from mission oriented managers and political sponsors, for example? If these distinctions are useful ones, do they co-exist within innovation projects?

High School Student's Experiment Goes into Space

The third flight of NASA's Space Shuttle, launched on March 22, had stowaways on board. In addition to the crew members and the normal assortment of flora and fauna that live on and in the human body, velvetbean caterpillar moths and honeybee drones were present for the historic trip into space. They are the subjects of an experiment designed by a Minnesota high school student. Todd E. Nelson is an 18-year-old senior at Southland Public School, Adams, Minnesota, and his experiment, Insects in Flight Motion Study, was chosen as the first student experiment to be placed on board a Space Shuttle flight. Nelson is one of ten finalists in the NASAsponsored National Space Shuttle Student Involvement Project for Secondary Schools. Developed in cooperation with the National Science Teachers Association, the project seeks to stimulate student interest in science and technology. The experiment is designed to pro vide data on the flight behavior in zero gravity of two species of flying insects with differing ratios of body mass to wing area. The experiment calls for placing a container aboard the Space Shuttle, stored in a drawer in the mid deck of the Orbiter. An astronaut would then remove the container (holding ten specimens of each species of insect), attach it to the wall of the mid deck, and observe their behavior. Their flight patterns would be filmed against a background grid. After filming, the astronaut would return the insects, still in their container, to the locker for the return flight and later analysis. While insect flight behavior has been studied before, it was for only a brief period of about 20 seconds in-parabolic flight. The Avionics Division of Honeywell, Inc. of Minneapolis, at the invitation of NASA, agreed to sponsor development of Nelson's experiment. Dr. Robert Peterson of the Honeywell Corporation and Nelson have worked together for the six months prior to the Shuttle at Honeywell's headquarters, preparing the experiment for flight. In addition, Honeywell has provided travel funds to enable Nelson to work with Peterson and to attend the liftoff, analyze data, and prepare a final report. The overall goal of the NASA project is to stimulate the study of science and engineering by engaging students in an annual competition to develop experiments suitable for flight aboard the Space Shuttle. The competition is open to students in grades 9 to 12, enrolled in American public, private, parochial, and overseas schools. Regional winners (about 200) and their teachers were invited to attend conferences held at NASA field centers where the students presented their proposals to teams of scientists. Based on advice provided by the scientists, regional winners made minor revisions in their proposals prior to final judging in Washington, D.C. The experiments of the remaining winners of the 1980-81 competition are being readied for inclusion on future Space Shuttle flights, as space is available. It is not surprising that seven of the ten winning proposals involve problems in biology. The titles include Biofeedback, Growth of Porifera in Zero Gravity, and Effects of Weightlessness on Arthritis. Information about future competitions may be obtained by writing to: Shuttle Student Involvement Project, NSTA, 1742 Connecticut Avenue, N.W., Washington, D.C. 20009.

Crustal Deformation Observatory

Under the joint direction of the University of California at Los Angeles and San Diego, the Crustal Deformation Observatory project at Pinyon Flat, California, has completed its first year. The overall aim of this project, sponsored by the U.S. Geological Survey, is to evaluate and improve instrumentation for measuring long‐period (days to years) crustal deformation in a technically active area. This research is being conducted at Piñon Flat Observatory by operating an array of differing instruments, each capable of resolving the signals generated by stresses associated with the San Jacinto and San Andreas fault zones. At this time there are 11 institutions involved, some on an informal basis, utilizing techniques ranging from NASA's project ARIES to Carnegie Institute's deep borehole strainmeters. Particular emphasis has been placed on establishing the coherence between different methods of long‐baselength (500 m) tilt measurements.

Ergonomics technology.

Many aspects of NASA's research programs and projects focus on the working environment of man. Ergonomics research has a broader application of technological spinoffs. This paper describes these research efforts and may have implications for environmental control in industry.

Distributed management of scientific projects: An analysis of two computer-conferencing experiments at NASA

Between August 1975 and March 1976, two NASA projects with geographically separated participants used a computer-conferencing system developed by the Institute for the Future for portions of their work. Monthly usage statistics for the system were collected in order to examine the group and individual participation figures for all conferences. The conference transcripts were analysed to derive observations about the use of the medium. In addition to the results of these analyses, the attitudes of users and the major components of the costs of computer conferencing are discussed.

An Actual Application of Collective Choice Theory to the Selection of Trajectories for the Mariner Jupiter/Saturn 1977 Project

This paper describes the use of decision analysis to facilitate a group decision-making problem in the selection of trajectories for the two spacecraft of the Mariner Jupiter/Saturn 1977 Project. This NASA project includes the participation of some eighty scientists, divided by specialization among eleven science teams. A set of thirty-two candidate trajectory pairs was developed by the Project, in collaboration with the science teams. Each science team then ordinally ranked and assigned cardinal utility function values to the trajectory pairs. The scientists used these data and statistics derived from collective choice rules in selecting the preferred trajectory pair.