Astrodynamics Commons^™

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 …

Special Effects: Antenna Wetting, Short Distance Diversity And Depolarization, Roberto J. Acosta

Online Journal of Space Communication

The Advanced Communication Technology Satellite (ACTS) communications system operates in the Ka frequency band. ACTS uses multiple, hopping, narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for bit-error-rates of 5x 10-7 or better over the continental United States. In order maintain this minimum system availability in all US rain zones, ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is to present the results of system and sub-system characterizations considering the statistical effects of system variances due …

Ka-Band System And Propagation Effects On System Performance, Roberto J. Acosta, Sandra Johnson

Online Journal of Space Communication

The Advanced Communication Technology Satellite (ACTS) is an experimental communications satellite system launched in September 1993. ACTS introduces many new technologies, including operation in the Ka frequency band. ACTS uses multiple hopping narrow beams and very small aperture terminal (VSAT) technology to establish a system availability of 99.5% for a bit-error-rates of 5x10-7 or better over the continental United States. In order to maintain a minimum system availability f 99.5% over all US rain zones ACTS uses an adaptive rain fade compensation protocol to reduce the impact of signal attenuation resulting from propagation effects. The purpose of this paper is …

Comparison Of Multiple Rain Attenuation Models With Three Years Of Ka Band Propagation Data Concurrently Taken At Eight Different Locations, Glenn S. Feldhake, Lynn Ailes-Sengers

Online Journal of Space Communication

In June 1996, Working Party 3M of the ITU-R presented research comparing the estimations of 10 rain attenuation models with the 186 station years of earth-space propagation data contained within the ITU-R database known as DBSG5. Now, twenty-one station years of new data taken exclusively in the Ka band (20.185 GHz and 27.505 GHz) across North America are measured against many of those same models. Results are presented both in terms of error statistics as well as in comparison to the ITU database results.

Rain Attenuation Model Comparison And Validation, Charles E. Mayer, Bradley E. Jaeger

Online Journal of Space Communication

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Ka-Band Propagation Modeling For Fixed Satellite Applications, Asoka Dissanayake

Online Journal of Space Communication

Propagation impairments produced by the troposphere are a limiting factor for the effective use of the 20/30 GHz frequency band. Use of smaller earth terminals, while very attractive for consumer and transportable applications, make it difficult to provide sufficient link margin for propagation related outages. In this context, reliable prediction of propagation impairments for low-availability systems becomes important. This paper addresses the issues related to predicting different types of propagation impairments as well as combining them together to determine the overall impact on satellite links over a wide range of outage probabilities.

A Prediction Model That Combines Rain Attenuation And Other Propagation Impairments Along Earth-Satellite Paths, Asoka Dissanayake, Jeremy Allnutt, Fatim Haidara

Online Journal of Space Communication

The rapid growth of satellite services using higher frequency bands such as the Ka-band has highlighted a need for estimating the combined effect of different propagation impairments. Many projected Ka-band services will use very small terminals and, for some, rain effects may only form a relatively small part of the total propagation link margin. It is therefore necessary to identify and predict the overall impact of every significant attenuating effect along any given path.

A procedure for predicting the combined effect of rain attenuation and several other propagation impairments along earth-satellite paths is presented. Where accurate models exist for some …

Acts Propagation Experiment: Experiment Design, Calibration, And Data Preparation And Archival, Robert K. Crane, Xuhe Wang, D. B. Westenhaver, Wolfhard J. Vogel

Online Journal of Space Communication

The National Aeronautics and Space Administration Advanced Communications Technology Satellite (ACTS) propagation experiment was designed to obtain slant-path attenuation statistics for locations within the United States and Canada for use in the design of low-margin Ka-band satellite communication systems. Experimenters at seven different locations have collected propagation data for more than two years. The propagation terminals used for the experiment were identical. A single preprocessing program was used by the experimenters to provide for automatic calibration, generation of attenuation histograms, and data archival. In this paper, the calibration procedures are described and estimates given for measurement accuracy.

ACTS provided beacons …

Ka-Band Propagation Measurements: An Opportunity With The Advanced Communications Technology Satellite (Acts), Robert Bauer

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS) was conceived at the National Aeronautics and Space Administration (NASA) as a follow-on program to its long history in satellite communications projects that have reduced the risk of developing new technologies that fall outside the sponsorship capability of the private sector.

To counter the foreign challenge that developed in the late 1970's to the once insuperable U.S. lead in this field, ACTS was developed to maintain the U.S. preeminence. Launched in September 1993 from the space shuttle, key technologies on ACTS include a multibeam antenna, a baseband processor, a 900-MHz wideband microwave switch matrix, …

Advanced Communications Technology Satellite (Acts): Design And On-Orbit Performance Measurements, Frank Gargione, R. Acosta, T. Coney, R. Krawczyk

Online Journal of Space Communication

The Advanced Communications Technology Satellite (ACTS), developed and built by Lockheed Martin Astro Space for the NASA Lewis Research Center, was launched in September 1993 on the Shuttle STS 51 mission. ACTS is a digital experimental communications test bed that incorporates gigahertz bandwidth transponders operating at Ka band, hopping spot beams, on-board storage and switching, and dynamic rain fade compensation. This paper describes the ACTS enabling technologies, the design of the communications payload, the constraints imposed on the spacecraft bus, and the measurements conducted to verify the performance of the system in orbit.

Historical Development: Acts Technology, Richard Gedney, Ron Schertler, Frank Gargione

Online Journal of Space Communication

The following material has been extracted from "The Advanced Communications Technology Satellite" book by Richard Gedney, Ron Schertler and Frank Gargione.

Issue 2: From The Guest Editor, Frank Gargione

Online Journal of Space Communication

Guest editor introduction

Historical Development: Acts Program Formulation, Richard Gedney, Ron Schertler, Frank Gargione

Online Journal of Space Communication

The following material has been extracted from "The Advanced Communications Technology Satellite" book by Richard Gedney, Ron Schertler and Frank Gargione.

Adaptive Control For Nonlinear, Time Varying Systems, John Zelina

Doctoral Dissertations and Master's Theses

It is common for aerospace systems to exhibit nonlinear, time varying dynamics. This thesis investigates the development of adaptive control laws to stabilize and control a class of nonlinear, time varying systems. Direct adaptive control architectures are implemented in order to compensate for time varying dynamics that could, for example, be caused by varying inertia resulting from fuel slosh or settling in a tank. The direct adaptive controller can also respond to external disturbances and unmodeled or nonlinear dynamics. Simulation results are presented for a prototype system that consists of two rotating tanks with time varying inertia due to the …

White Paper Report: Needs In Space Education For The 21st Century—Research, Higher Education, Training And Public Policy, Randall Johnson, Joseph Pelton, Henry Hertzfeld, Don Flournoy, Hussein J. Hussein

Online Journal of Space Communication

May 2, 2003

A Forum Seeking Innovative Answers

• New Approaches to Higher Education and Training
• Distance Learning, Tele-education and the Internet
• Shared Research Facilities and New Approaches to Research
• Joint University Projects
• Multidisciplinary Needs and International Perspectives and Languages
• Space and Security Issues Related to Education
• How to Attract More Students to Higher Education in the Space Field
• How to Prepare Incoming Students More Effectively for College
• Wide Spread Survey on Space Education to Find Concerns and New Solutions

From The Industry: Yasunori Matogawa, Ph.D., Professor Of Space Communications At The Institute Of Space And Astronautical Science, Yasunori Matogawa

Online Journal of Space Communication

Dr. Yasunori Matogawa is Professor at the Institute of Space and Astronautical Science directly reporting to the Ministry of Education, Science, Culture, Sports and Technology. He is also in charge of supervising Kagoshima Space Center in Kyushu as Director General. Widely considered to be the man of space education in Japan, Dr. Matogawa is the President for the Japan Society for Aeronautical and Space Sciences. Internationally, he is well-known as the Chairman of the International Astronautical Federation. The interview was conducted at Sophia University, Japan with the assistance of Dr. Tsutomu Kanayama (Email: [email protected]).

Students Interested In Satellite Communications Can Gain An Edge In The Job Market By Studying Science And Theory, Ben Chang

Online Journal of Space Communication

The mind has an extraordinary ability to see things that are hoped for, Arthur C. Clarke said in 1973. Years later he noted that it cost about $100, in terms of kilowatt-hours, to go to the moon, "whereas it costs about a billion dollars the way we've done it."

These two quotes from the grandfather of satellite communications and author of 2001: A SPACE ODYSSEY point to one of the primary qualities INTELSAT looks for in filling engineering positions: the ability to apply book knowledge to the practical aspects of satellite communications.

Model Curricula: University Of Texas Medical Branch

Online Journal of Space Communication

University of Texas Medical Branch UTMB/NASA Aerospace Medicine Residency

Model Curricula: University Of Oklahoma

Online Journal of Space Communication

University of Oklahoma Aerospace Engineering

Model Curricula: Space Foundation

Online Journal of Space Communication

The Space Foundation is a national non-profit organization advancing space awareness and space education.

The Space Foundation pursues the mission of vigorously advancing civil, commercial and national security space endeavors for a brighter future and supporting educational excellence through the excitement of space.

Model Curricula: Umea University, Carol Norberg

Online Journal of Space Communication

The town of Kiruna, lying 140 kilometres above the Arctic Circle in northernSweden, has for many years been considered the ‘‘space centre’’ of Sweden.The high latitude makes Kiruna an attractive base for international spaceresearch. This paper describes the practical-oriented Space EngineeringProgram run in Kiruna by the University of Umeå. The students on theprogram benefit from the expertise of resident and visiting space scientistsand engineers. The education is the only one of its kind in Sweden.

Model Curricula: Esa Telecom Training Programme

Online Journal of Space Communication

This paper describes the content of an e-training course on satellite communications prepared under contract to ESA and now available at the ESA Telecom User Support Office website. The contract to develop this online training was led by EADS Fleximage with significant contributions from a team of subcontractors including EADS Astrium, British Telecom Exact Technologies, ENSAE/ SUP'Aero and ISU. The course is divided into five modules covering the following areas in an animated and progressive way:

• Systems and Services
• Communication Link
• Networking
• Space Segment
• Earth Segment

Model Curricula: International Space University

Online Journal of Space Communication

How to educate Space professionals able to meet the needs of the Space community and the challenges of a changing Space sector in a changing world? The International Space University (ISU) was created in 1987 to educate Space leaders using a unique approach. ISU programs are based on a "3-I" International, Interdisciplinary and Intercultural) model which was built from discussions and meetings within the world Space community to meet its evolving needs.

Model Curricula: Ohio University

Online Journal of Space Communication

Programs of Education Relating to Satellite and Space Communication in:

Telecommunication Communications Systems Management

Electrical Engineering and Computer Science

Model Curricula: George Washington University

Online Journal of Space Communication

There is a growing need for qualified engineers, scientists, technicians, marketing and sales and management personnel in the field of satellite applications and only a few universities that are actually offering undergraduate or graduate degrees in this area.

Model Curricula: Embry-Riddle Aeronautical University

Online Journal of Space Communication

Many universities have added courses and curricula related to satellites and space. A search of the Internet reveals that few of these are designated degree programs in space studies degree, rather they are traditional programs offering courses and concentrations which involve study of space and space applications from several perspectives. The Internet search also reveals a large variation in both the titles and the curricula for these programs. The author has sought to standardize definitions, identify workable program names and suggest core courses. Five programs and their core courses are outlined for consideration.

Database Of Academic Institutions: International

Online Journal of Space Communication

Institutions, research centers and professional associations around the world that do research and teach content and skills relating to satellite and space communication.

Database Of Academic Institutions: United States K-12

Online Journal of Space Communication

Institutions, research centers and professional associations in the United States that do research and teach content and skills relating to satellite and space communication at the K-12 level.

Applied Reachability Analysis For Time-Optimal Spacecraft Attitude Reorientations, Layne C. Barrett

Theses and Dissertations

Satellite attitude reorientation has been of significant interest in astronautical engineering, and being able to reorient in a time-optimal manner has been of exceeding interest since the 1970s. Ensuring a spacecraft mission set can be conducted within a certain amount of time begs the question of whether or not a certain maneuver can be completed with a bounded control. This thesis answers that question by using the concept of reachability to provide reachable sets for different spacecraft reorientation scenarios. The reachable sets generated provide a range of initial states that guarantee a satellite reach a desired end orientation given a …