Space Vehicles Commons^™

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

n/a

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.

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.

Development Of High-Density Propulsion System Technologies For Interplanetary Small Satellites And Cubesats, Morgan Andrew Roddy

Graduate Theses and Dissertations

The goal of this research was to support the development of a novel propulsion system for small satellites (<180 kg) and CubeSats. This was pursued by conducting a collection of studies that were designed to provide engineering data that would be critical in designing a functional prototype. The novel propulsion system was conceived by the author to provide best-in-class performance for the small satellite and CubeSat families of spacecraft. This context presents specific design requirements that the presented technology attempts to satisfy. The most critical among these is high density; the propellant was designed to be stored with high density and the thruster was designed to be as compact as possible. The propulsion system is composed of two primary elements, a propellant generator and a thruster. The propellant generator works by sublimating a solid crystal into vapor and then using this vapor to etch a dense metal. The resulting gaseous byproducts of this reaction are the propellant. This dissertation used xenon difluoride (XeF2) vapor to etch tungsten (W) which react to form xenon gas (Xe) and tungsten hexafluoride (WF6). This approach gave a theoretical propellant storage density 5.40 g/cm3; and 5.17 g/cm3 was demonstrated. The sublimation dynamics of the XeF2 were studied as a function of surface area and temperature and it was found to be suitable for the intended application due to its high effluence rate; that is, it sublimates fast enough to be useful. The sublimation rates are on the order of 10’s of µg/s. The etch rate of XeF2 on W was also studied and found to be suitably fast to provide useful amounts of reactants for use as a propellant, again on the order of 1’s of µg/s. The thruster is an electrostatic radio frequency (RF) ion thruster design and is manufactured with Low Temperature Co-Fired Ceramic (LTCC) materials system and manufacturing technology. Manufacturing samples of the thruster were built at the University of Arkansas in July 2015 and tested at NASA’s Marshall Space Flight Center in May 2018. Testing validated the viability of the LTCC thruster and provided valuable information on how to improve the thruster’s design.

Nonlinear Least Squares 3-D Geolocation Solutions Using Time Differences Of Arrival, Michael V. Bredemann

Mathematics & Statistics ETDs

This thesis uses a geometric approach to derive and solve nonlinear least squares minimization problems to geolocate a signal source in three dimensions using time differences of arrival at multiple sensor locations. There is no restriction on the maximum number of sensors used. Residual errors reach the numerical limits of machine precision. Symmetric sensor orientations are found that prevent closed form solutions of source locations lying within the null space. Maximum uncertainties in relative sensor positions and time difference of arrivals, required to locate a source within a maximum specified error, are found from these results. Examples illustrate potential requirements …

Performance Enhancement And Characterization Of An Electromagnetic Railgun, Paul M. Gilles

Master's Theses

Collision with orbital debris poses a serious threat to spacecraft and astronauts. Hypervelocity impacts resulting from collisions mean that objects with a mass less than 1g can cause mission-ending damage to spacecraft. A means of shielding spacecraft against collisions is necessary. A means of testing candidate shielding methods for their efficacy in mitigating hypervelocity impacts is therefore also necessary. Cal Poly’s Electromagnetic Railgun was designed with the goal of creating a laboratory system capable of simulating hypervelocity (≥ 3 km/s) impacts. Due to several factors, the system was not previously capable of high-velocity (≥ 1 km/s) tests. A deficient projectile …

Single-Degree-Of-Freedom Experiments Demonstrating Electromagnetic Formation Flying For Small Satellite Swarms Using Piecewise-Sinusoidal Controls, Ajin Sunny

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis presents a decentralized electromagnetic formation flying (EMFF) control method using frequency-multiplexed sinusoidal control signals. We demonstrate the EMFF control approach in open-loop and closed-loop control experiments using a single-degree-of-freedom testbed with an electromagnetic actuation system (EAS). The EAS sense the relative position and velocity between satellites and implement a frequency-multiplexed sinusoidal control signal. We use a laser-rangefinder device to capture the relative position and an ARM-based microcontroller to implement the closed-loop control algorithm. We custom-design and build the EAS that implements the formation control in one dimension. The experimental results in this thesis demonstrate the feasibility of the …

Nanosatellite Launch Data-Logger (Sync), Christopher Martin Gerdom

Master's Theses

CubeSat designers are increasingly looking to incorporate delicate structures and optics into their payloads. These delicate payloads, however, may not survive the required absolute-worst-case launch vibration testing needed for flight certification. To help address this problem, and to better match testing conditions to real-world launch environments, this thesis introduces Sync, a compact 1/4U CubeSat payload designed to collect data on the vibrations and thermal environments CubeSats experience inside a deployer on the way to orbit. This data can be used to better understand the launch environment for different vehicles, and help develop new, more realistic testing guidelines that could enable …

Experimental Evaluation Of A Krypton Propellant Arrangement In A T-100-3 Hall-Effect Thruster, Adam Patel, Javier Cortina Fernandez, Justin Chow, Osvaldo Alejandro Martin, Alexey Shashurin

The Summer Undergraduate Research Fellowship (SURF) Symposium

Stationary Hall thrusters are electric, moderate-specific impulse propulsion systems developed in Russia. These devices manipulate electric and magnetic fields to expel ionized gas (plasma) components, resulting in thrust. The success of Hall-effect engines in USSR satellite-transfer missions quickly sparked western interest in the design. Extensive government and academic study commenced shortly after the dissolution of the Soviet Union, when the technology was made available to the United States. The common SPT-100 model was the primary subject of such studies. Unfortunately, limited literature exists for rare and uncommon Hall thruster models. The T-100-3 stationary plasma thruster suffers from this gap; few …