Astrodynamics Commons^™

Access To Education In Africa Via Satellite, Hala Ibrahim

Online Journal of Space Communication

The potential of satellite technologies to improve access to education in Africa is discussed in this paper. Education contributes to sustainable development in Africa. However, accessibility to quality education has been stalled by many barriers, including lack of infrastructure, lack of trained teachers, high teacher/student ratios and shortage of educational materials. Satellites are among the information and communication technologies (ICTs) with the potential to by-pass terrestrial barriers to deliver educational services to scattered users.

The Challenges Of Distance Education, Abdul Waheed Khan

Online Journal of Space Communication

Education is of extreme importance as it is key to equipping the workforce with the skills needed to develop national economies. The importance is exemplified by the "Education for All" movement, a global commitment to provide quality basic education for all children, youth and adults, which links directly to the UN Millennium Development Goals (MDGs). Sustainable development of quality primary education is dependent on complementary development in the secondary and tertiary education sectors. With economies relying more and more on the generation and application of knowledge, productivity is increasingly dependent on the development and spread of technological innovation. Higher education …

Satellite Distance Education In China, Tom Wang

Online Journal of Space Communication

The establishment of the China Education Television (CETV) station in July 1986, the broadcast of the first special TV channel for satellite education and the opening of the second special channel are widely regarded as three milestones in the early stage of satellite distance education in China.

Issue 11: Contributors, Don Flournoy

Online Journal of Space Communication

Biographical information for the Issue 11 contributors:

Daniel Butler

Don Flournoy

Scott Madry

Joseph Pelton

Optimization Of Interplanetary Transfer Trajectories Using The Invariant Manifolds Of Halo Orbits, Ryan Yedinak

Master's Theses

Traditionally, two-body dynamics have been used to design orbital trajectories for interplanetary missions using a series of Lambert’s transfers and gravity assists. Although these are reliable methods, they have extremely high fuel requirements, especially for missions to outer planets. From an orbital mechanics perspective, three ways of reducing fuel requirements for these types of missions are utilizing low energy transfer trajectories, applying low thrust engine parameters, and implementing orbit optimization techniques.

The goal of this thesis is to combine low energy transfers created from the dynamics of the Circular Restricted Three-Body Problem (CRTBP) with low-thrust orbit optimization techniques to develop …

Stochastic Satellite Air Drag With The Ballistic Coefficient As A Random Variable, Everett B. Palmer Iv

Theses and Dissertations

The drag acceleration caused by the Earth's atmosphere is a significant cause of prediction uncertainty for low Earth orbit satellites. Most existing research has focused on improving deterministic atmospheric density predictions or on density as a random variable. This research investigates a new paradigm and focuses on modeling the uncertainty caused by air drag using the ballistic coefficient, a component of air drag that is independent of the model used to predict atmospheric density. Time series of ballistic coefficient values were calculated and analyzed as random processes. These random processes were then used as the foundation of a stochastic satellite …

Application Of Net-Centric Communications For Disasters (Panel 1: First Responder), Norman Jones

Online Journal of Space Communication

Norman Jones, Transformational Communications Engineering presents: Application of Net-Centric Communications for Disasters

White Paper On Emergency Communications, Space And Advanced Communications Research Institute Space And Advanced Communications Research Institute

Online Journal of Space Communication

Prepared by the Space & Advanced Communications Research Institute (SACRI)

George Washington University

January 5, 2006

Note: This White Paper draws a number of sources including presentations at the National Conference on Emergency Communications (NCEC) held at the George Washington University on December 12-13, 2005. This conference featured some thirty different speakers selected from the federal as well as state and local governments, a wide range of industry spokespeople, several professional societies, relief organizations and NGOs, universities, and other interested parties. There were thirty different sponsors. These presentations, the attendees at this conference and the many sponsors of this event …

Issue 10: From The Guest Editors, Joseph Pelton, Neil Helm

Online Journal of Space Communication

Issue 10 introduction from the guest editors.

Euler's Three-Body Problem, Sylvio R. Bistafa

Euleriana

In physics and astronomy, Euler's three-body problem is to solve for the motion of a body that is acted upon by the gravitational field of two other bodies. This problem is named after Leonhard Euler (1707-1783), who discussed it in memoirs published in the 1760s. In these publications, Euler found that the parameter that controls the relative distances among three collinear bodies is given by a quintic equation. Later on, in 1772, Lagrange dealt with the same problem, and demonstrated that for any three masses with circular orbits, there are two special constant-pattern solutions, one where the three bodies remain …

Effects And Solutions On The Human Body After Long-Duration Space Flights, Jose Jaime Esquivel Patricio

McNair Research Journal SJSU

During the Cold War, President John F. Kennedy made it a mission for the National Aeronautics and Space Administration (NASA) to accomplish a lunar landing and return to Earth. The final lunar landing and the last time humans left Low Earth Orbit (LEO) was in December, 1972. However, 47 years have passed and the fascination with traveling into deep space remains alive and flourishing. A major problem with future human missions to Mars is the effects of microgravity and Mars’ 0.38g environment. Unfortunately, space medicine is limited and little is known about the effects of microgravity on the human body …

Issue 9: Contributors, D. Flournoy, Randall Johnson

Online Journal of Space Communication

List of issue 9 contributors.

Gps & Galileo: Prospects For Building The Next Generation Of Global Navigation Satellite Systems, Glen Gibbons Jr.

Online Journal of Space Communication

In the next 5 to 10 years, the world will experience the emergence of a true Global Navigation Satellite System (GNSS) - a compatible and, in many respects, interoperable system of systems. The U.S. Global Positioning System, Europe's Galileo, perhaps Russia's Glonass system, and regional augmentations including the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS), radiobeacon-based systems such as the U.S. Nationwide Differential GPS, and compatible commercial differential correction services will comprise this multifaceted GNSS. Common signal structures and frequency plans will enable combined user equipment that reduces the technical complexity and cost, while vastly …

New U.S. Gps Policy From A European Perspective, Martin U. Ripple, Alexis Vidal

Online Journal of Space Communication

On December 8, 2004, the President of the United States of America authorized the new U.S. Space-based Positioning, Navigation and Timing Policy. This new policy sets forth a forward-looking framework for the management of GPS and its augmentations. In particular, the new U.S. policy mentions interaction with other satellite navigation systems.

Following the establishment of a U.S.-E.U. framework agreement for cooperation between GPS and Galileo, signed on June 26, 2004, European policy makers and industrialists expected clear statements on cooperation and interoperability issues from the new U.S. GPS policy. Regrettably, the related recommendations hold short of the need for cooperation …

Receiver Performance For An Enhanced Dgps Data Channel, Gregory Johnson, Michael Kuhn, Peter F. Swaszek, Richard Hartnett, Per Enge

Online Journal of Space Communication

The Coast Guard currently operates a maritime differential GPS service consisting of two control centers and over 85 remote broadcast sites. This service broadcasts GPS correction information on marine radiobeacon frequencies to improve the accuracy and integrity of GPS. The existing system provides differential corrections over a medium frequency carrier using minimum shift keying (MSK) as the modulation method. MSK is a version of the Continuous Phase Frequency Shift Keying (CPFSK) modulation technique that is "spectrally compact," meaning that it is a narrow band modulation scheme. In a binary signaling channel, the two instantaneous frequencies for this modulation method are …

Space Based Real-Time Kinematic Gps For National Geodetic Survey Texas Height Modernization, S. D. Lyle, D. M. Mulcare

Online Journal of Space Communication

Height Modernization is a program in NOAA's National Geodetic Survey (NGS) that uses the Global Positioning System (GPS) and other new technologies to increase the accuracy of elevation measurements that comprise the vertical portion of the National Spatial Reference System (NSRS). Height Modernization Program within NGS is working with states to improve the height component of their survey control networks and related products. Texas A&M University- Corpus Christi (A&M-CC) was designated as the recipient of a grant under the Program during the most recent Congressional cycle. In order to best coordinate and manage the activities funded by the grant, A&M-CC …

Sea Surface Wave Information Using Gps Sea Reflected Signal - Wave Height, Shigeyuki Okuda, Yasuo Arai, Nobuyoshi Kouguchi

Online Journal of Space Communication

In case of positioning by GPS, the direct signal from the satellite to the receiver is ordinarily utilized, but the multipath signal is regarded as one error source that deteriorate the positioning accuracy. In this paper, we focus on characteristics of the reflected signal, and had a few simulation tests. The correlator output signals are checked out and compared to the change of wave height and the wave period.

In this paper we describe that in sufficient long wave compared with reflection area size we can measure an accurate wave height, and by pointing antenna beam center from two directions …

Moving Map And Situational Awareness Capabilities Of The Dagr, Gary L. Bachman

Online Journal of Space Communication

This paper presents an overview of the Moving Mapp and Situational Awareness capabilities of the Defense Advanced GPS Receiver (DAGR) military handheld GPS receiver (refer to Figure 1), and how these capabilities can be utilized for other applications. The paper first presents an overview of situational awareness and moving maps as provided by handheld GPS receivers, factors driving the DAGR's requirements, and the requirements themselves.

This paper presents the system design in a two-part approach corresponding to the two primary components of the system: 1) importing digital map products into the DAGR and 2) displaying moving maps and situational awareness …

Egnos Terrestrial Regional Augmentation Networks Based On Ais For River Information Services, M. Jandrisits, J. C. De Mateo, G. Abwerzger

Online Journal of Space Communication

Within the ESA Advanced Research Telecommunications program ARTES-5, the project GALEWAT (Galileo and EGNOS for Waterway Transport) aims at introducing EGNOS into River Information Services (RIS) through the Automatic Identification System (AIS), a link that is mandatory for seagoing vessels above 300 GT.

The GALEWAT project comprises several phases: During the initial definition phase, the system architecture and user equipment have been defined in line with standards and international recommendations. This phase was followed by the implementation phase, aiming at developing and setting up the equipment. Finally, the project will be completed by an extensive demonstration phase, which is currently …

Geosynchronous Satellite Use Of Gps, Jennifer L. Ruiz, Charles H. Frey

Online Journal of Space Communication

The purpose of this study was to determine the accuracy of GPS use for a geosynchronous (GEO) satellite. Current missions at GEO altitude mainly use traditional ranging for orbit determination. With changing mission requirements and the increase in the number of GEO missions, utilizing GPS signals is becoming an increasingly attractive alternative for position and timing determination. A previous ION paper discusses the use of GPS data for a particular geosynchronous satellite mission and is included here as a reference. GPS use at GEO is primarily limited by the availability of the spillover from the GPS earth coverage signal. The …