Astrodynamics Commons^™

Commodity Computing Clusters At Goddard Space Flight Center, John E. Dorband, Josephine Palencia, Udaya Ranawake

Online Journal of Space Communication

The purpose of commodity cluster computing is to utilize large numbers of readily available computing components for parallel computing to obtaining the greatest amount of useful computations for the least cost. The issue of the cost of a computational resource is key to computational science and data processing at GSFC as it is at most other places, the difference being that the need at GSFC far exceeds any expectation of meeting that need. Therefore, Goddard scientists need as much computing resources that are available for the provided funds. This is exemplified in the following brief history of low-cost high-performance computing …

Multi-Sensor Image Registration, Fusion And Dimension Reduction, Jacqueline Le Moigne

Online Journal of Space Communication

With the development of future spacecraft formations comes a number of complex challenges such as maintaining precise relative position and specified attitudes, as well as being able to communicate with each other. More generally, with the advent of spacecraft formations, issues related to performing on-board and automatic data computing and analysis as well as decision planning and scheduling will figure among the most important requirements. Among those, automatic image registration, image fusion and dimension reduction represent intelligent technologies that would reduce mission costs,would enable autonomous decisions to be taken on-board, and would make formation flying adaptive, self-reliant, and cooperative. For …

Earth Satellite Direct Broadcast And Unmanned Aerial Vehicles, Patrick Coronado

Online Journal of Space Communication

Direct Readout of directly broadcasted remote sensing data has become the driving force for real-time data processing and global data product distribution. Direct readout methods of aerial and spaceborne platforms carrying spectral imagers and profilers have allowed immediate local monitoring of our environment to support natural and man made hazards, bio-mass changes and urban and rural monitoring. This paper describes NASA's latest direct readout technologies necessary to undertake real-time aerial and spaceborne remote sensing for the next generation environmental satellites and uninhabited aerial vehicles.

Knowledge Base Data Mining And Machine Learning In A Parallel Computing Environment, William J. Campbell, Samir Chettri

Online Journal of Space Communication

The expectation of this research is to greatly broaden the use of remotely sensed imagery by providing a novitiate user, access to embedded information and knowledge without embarking upon a full-scale research project to complete the content extraction, storage and retrieval process. The intent of our approach is to develop an intelligent system that can adapt to changes or new information and learn from these changes. This will drastically alter the approach researchers take in using any digital imagery by opening the scientific discovery process, particularly to disciplines that have not traditionally used imagery due to the complexity of the …

Remote Sensing Of Informal Housing Settlements In Metropolitan Bangkok, Curtis N. Thomson

Online Journal of Space Communication

In 1988 the National Housing Authority of Thailand estimated that about 10 percent of the population was living in 1300 slum or squatter settlements (officially designated as 'congested communities) within the Bangkok metropolitan area. These settlements are located in a number of areas throughout the city, established on both public and private land and are consist of a variety of housing at very high densities (30 units per 1600 sq.m.). Due to the sometimes transient nature or these communities, or the speed with which they can develop, as well as the lack of information about the residents who occupy these …

Neighborhood Pattern Recognition From Mailing Information: Links With Satellite Imagery, Victor Mesev

Online Journal of Space Communication

The notorious difficulties of sensing urban areas remotely have traditionally limited accuracy and thematic detail to coarse generalizations. With the advent of very high spatial resolution satellite imagery comes the opportunity to generate much finer scale inventories of the geography of cities. However, urban reconstruction from imagery is still limited to the classification of physical land covers; and land use still, on the whole, is inferred from the spectral composition of land covers. What is needed to improve urban image pattern recognition and classification accuracy is for GIS to keep pace with the demand for finer spatial resolution ancillary data …

Introduction To Hyperspectral Image Analysis, Peg Shippert

Online Journal of Space Communication

The most significant recent breakthrough in remote sensing has been the development of hyperspectral sensors and software to analyze the resulting image data. Fifteen years ago only spectral remote sensing experts had access to hyperspectral images or software tools to take advantage of such images. Over the past decade hyperspectral image analysis has matured into one of the most powerful and fastest growing technologies in the field of remote sensing.

The "hyper" in hyperspectral means "over" as in "too many" and refers to the large number of measured wavelength bands. Hyperspectral images are spectrally overdetermined, which means that they provide …

Spectrometry And Hyperspectral Remote Sensing Of Urban Road Infrastructure, Martin Herold, Margaret E. Gardner, Val Noronha, Dar A. Roberts

Online Journal of Space Communication

Based on a comprehensive regional spectral library from spectrometer ground measurements and high-resolution hyperspectral AVIRIS data, this research investigates generic spectral characteristics, and related mapping capabilities and limitations for extracting roads of various types, delineating road centerlines, and surveying pavement quality within the urban environment. The methods are generally successful in identifying roads and road pavement types, but inaccuracies arise from spectral similarities between asphalt surfaces and specific roofing materials. Findings indicate that it is possible to spectrally characterize and estimate age of pavement and a few specific asphalt surface quality parameters (e.g. raveling). Finally, this research argues that the …

Introduction To Remote Sensing: Online Resources, Hugh Bloemer, Dale Quattrochi

Online Journal of Space Communication

Several quite useful online resources have been developed throughout the world. Below are links to some of these online Remote Sensing resources.

Ohioview: A Case Study In Progress, James K. Lein

Online Journal of Space Communication

OhioView is a consortium of 10 state universities within Ohio established to promote the low-cost distribution of US Government civilian satellite data for public use. Dedicated to the goal of reducing the financial and technological barriers to use remotely sensed satellite data, OhioView has made a significant contributions to the educational, research and public use of satellite imagery through a continuing program of focused and applied land cover studies, expanded university level teaching, and public and private outreach and training. A grassroots organization formed in 1996 by its member universities, OhioView's mission is to develop remote sensing applications, create educational …

Introduction To Remote Sensing: Remote Sensing Satellites, Hugh Bloemer, Dale Quattrochi

Online Journal of Space Communication

Introduction to Remote Sensing: Remote Sensing Satellite.

Introduction To Remote Sensing: Science For Society, Ronald J. Birk, Tsengdar Lee

Online Journal of Space Communication

Science for Society: Extending Earth Science Research Results into Decision Support Tools

Introduction To Remote Sensing: Americaview Consortium, Hugh Bloemer, Dale Quattrochi

Online Journal of Space Communication

The AmericaView Consortium is a network of several state consortia whose goal is to expand remote sensing education, research and innovation.

A Remote Sensing Tutorial, Nicholas M. Short

Online Journal of Space Communication

A Remote Sensing Tutorial

Issue 3: From The Guest Editors, Hugh Bloemer, Dale Quattrochi

Online Journal of Space Communication

What is Remote Sensing?

Acts Shut Down: April 28, 2004, Frank Gargione

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS) was shut down on Wednesday April 28 after more than ten years in orbit. The satellite, still fully operational and in the hardware configuration set at launch, was shut down due a funding shortfall, in spite of repeated efforts by NASA and the Ohio Consortium for Advanced Communications to find new sources of support.

Edward Ashford, Edward Ashford

Online Journal of Space Communication

Corporate Development Unit Leader at SES-ASTRA

Jeffrey Grant, Jeffrey Grant

Online Journal of Space Communication

Vice President and Chief Technical Officer of Astrolink, a joint venture of several communications companies

Edward Fitzpatrick, Edward Fitzpatrick

Online Journal of Space Communication

Vice President of Hughes Network Systems

Tom Brackey, Tom Brackey

Online Journal of Space Communication

Executive Director, Technical Operations for External Affairs, and Chief Scientist for internal technical matters,Hughes Space and Communications Company

Joseph Rothenberg, Joseph Rothenberg

Online Journal of Space Communication

NASA's Associate Administrator for Space Flight

Gerald Barna, Gerald Barna

Online Journal of Space Communication

Acting Deputy Director of the NASA Glenn Research Center

Advanced Shipboard Communications Demonstrations With Acts, Roy A. Axford, T. C. Jedrey, M. Rupar

Online Journal of Space Communication

For ships at sea, satellites provide the only option for high data rate (HDR), long haul communications. Furthermore the demand for HDR satellite communications (SATCOM) for military and commercial ships, and other offshore platforms is increasing. Presently the bulk of this maritime HDR SATCOM connectivity is provided via C-band and X-band. However, the shipboard antenna sizes required to achieve a data rate of, say T1 (1.544 Mbps) with present C-/X-band SATCOM systems range from seven to ten feet in diameter. This limits the classes of ships to which HDR services can be provided to those which are large enough to …

A Ka-Band High Data Rate Shipboard Satellite Terminal, M. Rupar, David Beering, D. Hoder

Online Journal of Space Communication

A fully articulated steerable shipboard satellite antenna system operating at Ka-band was developed by engineers from the Naval Research Laboratory (NRL), NASA's Glenn Research Center, and a number of industry partners. A series of tests conducted in October of 1998 on Lake Michigan achieved an unparalleled data rate transmission of 45 megabits per second (Mbps) between a moving vessel at sea and a fixed-earth station using NASA's Advanced Communications Technology Satellite (ACTS). Network and application layer tests ran concurrently with the data rate transmission trials, examining TCP/IP file transfers, video and voice transfer technologies, and Asynchronous Transfer Mode (ATM) techniques. …

Gigabit Satellite Network For Nasa's Advanced Communication Technology Satellite (Acts): Features, Capabilities, And Operations, M. Bergamo, D. Hoder

Online Journal of Space Communication

This paper describes the Gigabit Satellite Network (GSN) being developed under joint sponsorship of NASA and ARPA. The system will use the wide-band Satellite Switched Time Division Multiple Access (SS-TDMA) capability and hopping beam antennas of NASA's Advanced Communications Technology Satellite (ACTS). The GSN network will provide full-duplex SONET services over satellite at OC-3 (155.54 Mb/s) and OC-12 (622.078 Mb/s) rates. Typical applications will include connection of distributed SONET/ATM fiber "islands" over satellite, wide-area distributed supercomputer networking, high-definition digital TV, and high-speed file transfer.

The RF link consists of 30 GHz uplink and 20 GHz downlink signals transmitted using a …

Acts 118x Final Report High-Speed Tcp Interoperability Testing, W. Ivancic, M. Zernic, D. Hoder, D. Brooks, David Beering, A. Welch

Online Journal of Space Communication

With the recent explosion of the Internet and the enormous business opportunities available to communication system providers, great interest has developed in improving the efficiency of data transfer using the Transmission Control Protocol (TCP) of the Internet Protocol (IP) suite. The satellite system providers are interested in solving TCP efficiency problems associated with long delas and error-prone links. Similarly, the terrestrial community is interested in solving TCP problems over high-bandwidth links. Whereas the wireless community is intested in improving TCP performance over bandwidth constrained, error-prone links.

NASA realized that solutions had already been proposed for most of the problems associated …

A History Of The Improvement Of Internet Protocols Over Satellites Using Acts, M. Allman, S. Ostermann, H. Kruse

Online Journal of Space Communication

This paper outlines the main results of a number of ACTS experiments on the efficacy of using standard Internet protocols over long-delay satellite channels. These experiments have been jointly conducted by NASA's Glenn Research Center and Ohio University over the last six years.

The focus of our investigations has been the impact of long-delay networks with non-zero bit-error rates on the performance of the suite of Internet protocols. In particular, we have focused on the most widely used transport protocol, the Transmission Control Protocol (TCP), as well as several application layer protocols. This paper presents our main results, as well …

Nasa Acts Satellite: A Disaster Recovery Test, H. Kruse, D. Flournoy

Online Journal of Space Communication

In September 1993, NASA launched its long-awaited Advanced Communication Technology (ACTS) satellite. ACTS is a $500 million experimental all-digital spacecraft hosting a number of first-time technologies: on-board processing and switching, high-powered electronically hopping spot beams, adaptive rain-fade compensation and opening of the Ka frequency band.

Among the earliest of the tests on the new satellite was a NASA sponsored project conducted by Ohio University and its commercial partner, the Huntington National Bank. HNB is a $17 billion regional bank with 338 offices in fourteen states. Transactions on HNB's data networks currently travel on terrestrial T-1 lines. The Ohio University/HNB tests …

Survey Of Advanced Applications Over Acts, Robert Bauer, Paul Mcmasters

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS) system provided a national testbed that enabled advanced applications to be tested and demonstrated over a live satellite link. Of the applications that used ACTS, some offered unique advantages over current methods, while others simply could not be accommodated by conventional systems. The initial technical and experiments results of the program were reported at the 1995 ACTS Results Conference, in Cleveland, Ohio. Since then, the Experiments Program has involved 45 new experiments comprising 30 application experiments and 15 technology related experiments that took advantage of the advanced technologies and unique capabilities offered by ACTS. …

Propagation Effects Handbook For Satellite Systems Design, Louis J. Ippolito

Online Journal of Space Communication

This paper describes the latest edition of the NASA Propagation Effects Handbook for Satellite Systems Design and presents a summary of application of the handbook information to satellite link design and performance. NASA, which has supported a large part of the experimental work in radiowave propagation on space communications links, recognized the need for a reference handbook of this type, and initiated a program in the late 1970's to develop and update a document that will meet this need. The Fifth Edition provides, in a single document, an update to two previous NASA handbooks; the fourth edition of a handbook …