Civilian Satellite Research Articles

Ohioview: The Leadership Role of Libraries in Science and Technology Partnerships

The Ohioview Research Consortium was formed to improve distribution and access to data acquired from U.S. Government civilian satellites. Ohioview is a group of Ohio universities, the U.S. Geological Survey's EROS Data Center in Sioux Falls SD, the NASA Glenn Research Center in Cleveland OH, The Ohio Library and Information Network, and NREN. What is unique about this consortium is that the university library component has been called upon to play a strong leadership role. Background of the Ohioview Research Consortium is discussed, as well as challenges the group has faced. Finally the role of the Miami University Libraries in the Ohioview consortium is discussed.

On signal structures for GNSS-2

This paper summarizes the main results of an early investigation on desirable signal structures for the European Galileo civil satellite navigation system. Stemming from the requirements for increased accuracy, reduced time-to-first-fix and integrity information provision, the report describes the logical steps and the related numerical results leading to a novel Galileo signal definition. Although the final parameter definition is largely based on European system constraints, a number of design guidelines like the use of spectrally efficient square-root raised-cosine chip shaping and enhanced data broadcasting are expected to be of general applicability to any future satellite navigation system.

Creation of a unified network of monitoring and correction stations for navigation support in Ukraine

The paper reviews the creation of a network of monitoring and correction stations in Ukraine ensuring the implementation of national plans for the radio navigation support of various sectors of the economy using NAVSTAR and GLONASS satellite radio navigation systems including long-term plans for connecting this network to the GNSS global civil satellite navigation system based on the European projects EGNOS and GALILEO.

Loran-C in a European Navigation Perspective

After a brief overview of Loran-C system operation and performance, the present situation of the system in Europe is described. Loran-C is now in operation under the NELS agreement in north-western Europe in newly established chain configurations with old and new transmitter positions. Parallel to Loran-C the Russian equivalent, Chayka, is also operating, with three chains in Europe. There is an agreement between Norway and Russia concerning cooperation and possibly joint chain operations between the two system providers in the north; similar agreements in the Baltic and Mediterranean/Black Sea areas are being worked on. The situation around the Iberian peninsula has not yet been clarified. Being the only long/medium-range terrestrial system in Europe in the 2000+ time frame, Loran-C could be seen as a supplement to satellite systems. Due to the good penetration properties of its low-frequency signals, it can be used in many circumstances where satellite systems fail because of limited satellite visibility. Integration of Loran-C and (differential) satellite receivers, where Loran-C is calibrated by the satellite system as long as there are enough visible satellites, could in fact give the best of both worlds. For this reason, Loran-C is being considered in the perspective of a future international, civil satellite navigation system, initiated in Europe.

COST-DRIVEN DESIGN OF SMALL SATELLITE REMOTE SENSING SYSTEMS

Earth remote sensing (alongside communications) is one of the key application of Earth-orbiting satellites. Civilian satellites in the LANDSAT and SPOT series provide Earth images which have been used for a vast spectrum of applications in agriculture, meteorology, hydrology, urban planning and geology, to name but a few. In the defence sector, satellite remote sensing systems are a critical tool in strategic and tactical planning – for the countries which can afford them. To date, remote sensing satellites have fallen into one of these two categories: military missions driven by the requirement for very high resolution and orbital agility; and multipurpose civil satellites using general purpose sensors to serve a diverse community of end users. For military-style missions, the drive to high resolution sets the requirements for optics, attitude control and downlink data bandwidth. For civil missions, the requirement to satisfy multiple, diverse user applications forces compromises on spectral band and orbit selection. Although there are exceptions, many small satellite remote sensing missions carry on in this tradition, concentrating on ultra high resolution products for multiple user communities. This results in satellites costing on the order of US $100 M, not optimised for any particular application. This paper explores an alternative path to satellite remote sensing, aiming simultaneously to reduce cost and to optimise imaging products for specific applications. By decreasing the cost of the remote sensing satellite system to a critical point, it becomes appropriate to optimise the sensor's spectral and temporal characteristics to fit the requirements of a small, specialised user base. The critical engineering trade-off faced in a cost driven mission is how to reduce mission cost while still delivering a useful product to the selected user. At the Surrey Space Centre, we have pursued an engineering path using two dimensional CCD array sensors, commercial off-the-shelf lenses and gravity-gradient stabilised microsatellites. In spite of the inherent limitations of such systems, recent successes with the Thai Microsatellite Company's Thai-Phutt satellite show that a system costing in the region of US $3 million, can approach the spectral and spatial characteristics of LANDSAT. Surrey's UoSAT-12 minisatellite (to be launched April, 1999) will further develop this cost-driven approach to provide 10 m panchromatic resolution and 30 m multi-spectral resolution. This paper describes the Thai-Phutt and UoSAT-12 imaging systems, explaining the engineering methods and trade-offs. Although Surrey is presently the only centre presently pursuing such implementations, our paper shows that they deserve wider consideration.

Co-ordination of satellite and data programs: The committee on earth observation satellites' approach

Every year, an average of eight new civilian remote sensing satellite missions are launched. Cumulatively, over 250 such missions, each with a cost equivalent in current value to between $US 100 million to $US 1000 million, have been sponsored by space agencies in perhaps two dozen countries. These missions produce data and information products which are vital for informed decision making all over the world, on matters relating to natural resource exploitation, health and safety, sustainable national development, infrastructure planning, and a host of other applications. By contributing to better scientific understanding of global changes in the atmosphere, land surface, oceans and ice caps, these silently orbiting sentinels in the sky make it possible for governments and industries to make wiser environmental policy decisions and support the economic development needs of humanity. The international Committee on Earth Observation Satellites (CEOS) is the premier world body for co-ordinating and planning civilian satellite missions for Earth observation. Through its technical working groups and special task teams, it endeavours to: • • maximise the international benefits from Earth observation satellites; and • • harmonise practice in calibration, validation, data management and information systems for Earth observation. CEOS encompasses not only space agencies (data providers), but also the great international scientific and operational programs which rely on Earth science data from space. The user organisations affiliated with CEOS, together with the mission operators, attempt to reconcile user needs with the complex set of considerations — including national interests, cost, schedule — which affect the undertaking of space missions. Without such an internationally co-ordinated consensual approach, there is a much greater risk of waste through duplication, and of missed opportunity, or through the absence of measurements of some vital physical or biological parameter by space borne sensors. Mechanisms used by CEOS to carry out these tasks are built upon consensus and understanding, as well as on technology transfer between countries. An area of recent heightened endeavour in CEOS has been to determine and address the special needs of developing countries in respect of Earth observation data. In the next several years, a new wave of Earth observation will break, as the private sector, revitalised with decommissioned military technology, brings exciting new capabilities to international remote sensing. With rapidly burgeoning markets in spatial information or geomatics, as well as the continuing thirst of science programs for spatial information, there is a challenge upon the international space community to reassess continually, the most expedient and socially constructive means of making available in a fair and open way, geographically-reference information obtained with space observation systems.

LEO/MEO systems --- Global mobile communication systems

LEO/MEO systems are moving from a dream to a reality, their global reach is becoming apparent with the launch of the first LEO satellites. The global mobility offered by these systems is expected to have a profound effect on the way that organizations and individuals operate. Billions of dollars are invested in the research and development of LEO/MEO based communication systems, and larger amounts will be needed for their ongoing operation and use. Many global satellite based systems have been announced over the last decade, Ellipsat, Globalstar, ICO, Iridium, M?Star, Odyssey, Orbcomm, and Teledesic, are just a few of the many systems in deployment or under development. Being such a risky venture, limited experience exists in developing and managing large scale civilian satellite based mobile communication systems. Many interesting and challenging research issues are faced by the designers and operators of such systems. This paper presents the different approaches to the configuration of the various LEO and MEO based communication systems. It compares their advantages and disadvantages, and analyzes their economic viability. Based on the analysis, it is possible to identify the specific roles that each type will play in the global communication market. The paper presents and discusses some of the important research areas involved in their development, configuration, maintenance, operation and management. In particular, it introduces the problem of gateway placement in LEO/MEO systems and presents a mathematical formulation of the problem.

Could civil satellites monitor nuclear tests?

As the momentum for further cuts in nuclear weapons grows and fears of nuclear proliferation increase, the need to monitor nuclear testing is becoming more pressing. While military observation satellites are already used for this purpose, this article argues that greater independence and impartiality could be achieved through the use of civilian remote sensing satellites, whose images could be made available to the International Atomic Energy Agency (IAEA). How images from space are processed and interpreted is described, as is how civil satellites might be used to verify a comprehensive test ban treaty. Four options open to the IAEA for utilizing remotely sensed images are discussed.

Content based image retrieval systems

Images are being generated at an ever-increasing rate by sources such as defence and civilian satellites, military reconnaissance and surveillance flights, fingerprinting and mug-shot-capturing devices, scientific experiments, biomedical imaging, and home entertainment systems. For example, NASA's Earth Observing System will generate about 1 terabyte of image data per day when fully operational. A content-based image retrieval (CBIR) system is required to effectively and efficiently use information from these image repositories. Such a system helps users (even those unfamiliar with the database) retrieve relevant images based on their contents. Application areas in which CBIR is a principal activity are numerous and diverse. With the recent interest in multimedia systems, CBIR has attracted the attention of researchers across several disciplines. >

An example of satellite multisensor data fusion

Data fusion is a generic term for the general field of applied methods used in integrating and displaying data from multiple sources and is one approach to the analysis of complementary remote sensing imagery. Fusion techniques can be used in the generation of fine spatial resolution multispectral data which are not currently available from civilian satellite remote-sensing platforms, but which may be acquired routinely by the next generation of spaceborne sensors. In this paper, some of the basic procedures and applications of fusion are reviewed in relation to ecological and geological remote sensing. Three new images generated from the fusion of SPOT High Resolution Visible (HRV), panchromatic (10 m, visible), and multispectral (20 m, green, red, infrared) data are presented. An improvement in overall classification accuracy of up to 9% has been recorded when using a fused data in classification of six vegetation communities in a subarctic, alpine environment in Canada's Yukon.

Navstar GPS and GLONASS: global satellite navigation systems

Both the Navstar GPS and GLONASS satellite navigation systems, developed respectively by the United States and the Soviet Union (now the Commonwealth of Independent States), are now planned to become operational by the year 1994/95. Both systems are capable of providing the civil community with high-precision position-fixes and/or timing references on a continuous, world-wide basis. For many years both systems have had satellites in orbit in order for pre-operational testing to be conducted. The paper discusses (a) the widely-differing launch histories of both systems, (b) developments in the planned use of orbits, (c) the deliberate degradation of accuracy by the use of selective availability and (d) progress in plans to provide a joint Navstar GPS/GLONASS civil satellite navigation system, possibly integrated with other satellite ranging systems.

Viewing the Earth: The Social Construction of the Landsat Satellite System.

Viewing the Earth examines the role played by interest groups in shaping the process of technological change, offering valuable insights into how technologies evolve. It traces the history of Landsat from its origins through the launch and use of the first few satellites, showing how a variety of forces shape the form and the eventual reception of any new technology.The Landsat earth resources satellite system was a project of The National Aeronautics and Space Administration that was created to collect data about earth resources from space. The first satellite was launched in 1972 with great fanfare and high expectations. The data proved useful for everything from finding oil to predicting harvests, yet today the successful commercialization of the program is still uncertain. Why?To answer this question, Pamela E. Mack focuses on the negotiating process that went on among different parts of the space agency, other interested government agencies, and various organizations that were potential users of the data. This formal and informal negotiating process, she points out, involved not only choices between alternative technologies and the satellite but also conflicting definitions of what the satellite would do. The story is full of fascinating detail, from the concerns of the intelligence community over civilian satellites looking at the earth to the politics of agricultural survey.

Power For Ariane

THE European satellite launcher Ariane which will be celebrating its eleventh year of service next Christmas has got its fifth wind. The new version is scheduled to leave its launching pad in French Guiana in 1995, thus adding a further advanced stage to versions 3 and 4. Its broadened shoulders will first be required to bear the burden of keeping the leading position gained by Ariane‐space on the civilian satellite launch market. The competition will be fierce. Since 1989 the American space industry has been racing to the front with the new versions of the Delta and Atlas‐Centaur launchers. Japan is preparing to fire its first 112 rocket and the Soviet Union is offering the services of its Proton heavy launchers.

Who will fund Landsat?

A first‐ever joint hearing of the Science, Space, and Technology Committee and the House Permanent Select Committee on Intelligence was held on June 26 to ascertain the true value of the civilian satellite program—Landsat—to the scientific, environmental, and military communities.Landsats collect multispectral images that are used for such purposes as environmental monitoring, oil and gas exploration, and national security. Since the first launch in 1972, Landsat has provided a continuous data record that has proved invaluable in global change research. Currently, Landsats 4 and 5 are in orbit, with Landsat 6 still on schedule for a mid‐1992 launch. No funding has been requested for any follow‐on to Landsat 6, making users of the data uncertain that their future projects will go ahead.

Navstar GPS and GLONASS: Global satellite navigation systems

Both the Navstar GPS and GLONASS satellite navigation systems developed respectively by the U.S.A. and the Soviet Union are now planned to become operational by 1995. Both systems are capable of providing the civil community with high-precision position-fixes and/or timing references on a continuous, world-wide basis. Already both systems have several satellites in orbit in order for pre-operational testing to be conducted. The paper discusses (i) the widely-differing launch histories of both systems, (ii) developments in planned use of orbits, (iii) the deliberate degradation of accuracy by the use of selective availability, (iv) progress in plans to provide a joint Navstar GPS/GLONASS civil satellite navigation system possibly integrated with other satellite ranging systems and (v) current status of both systems.

Civil Satellite Navigation and Location Systems

1. INTRODUCTION. The American Global Positioning System (GPS/Navstar) and the USSR's Glonass are superb demonstrations of high technology but we should not forget that they were designed and implemented for a very different set of circumstances from that of the civil surveyor and navigator. Many of their features are not required for civil purposes and it is perfectly possible to get excellent results for many civil applications without the vast expenditure that went into those systems. This paper describes some of the ways in which it is proposed that satellites, not necessarily launched for the purpose, might be, and are being, exploited for civil navigation and location.

The Development of Civil Satellite Navigation in Europe

Despite the global coverage and high accuracy achievable through GPS and GLONASS, a number of organizations in Europe see a need for alternative satellite-based navaids. NAVSAT, GRANAS, Rexstar, Locstar, and INMARSAT'S proposed enhancements of GPS/SPS all use existing geostationary communications satellites. NAVSAT adds satellites in highly inclined orbits to those in geostationary orbit to achieve global coverage. Institutional and straight commercial issues assume considerably more importance in civil than in military systems.

Investigations of spot cartographic applications in the u.s. geological survey

The U.S. Geological Survey has a longstanding commitment to the advancement of the technology and applications of remotely sensed data from civilian satellite systems. In the past, research based on satellite data was primarily directed toward natural resource and land use applications rather than cartographic applications. The availability of high-resolution, stereoscopic data from the sensors on the Système Probatoire d’Observation de la Terre (SPOT) satellite platform provides new opportunities for cartographic applications. The potential applications include production of satellite image and topographic maps, and generation of digital elevation data. Investigations into these applications of SPOT data were recently initiated by the U.S. Geological Survey.

Remote sensing strategies for global resource exploration and environmental management

Since 1972, satellite remote sensing, when integrated with other exploration techniques, has demonstrated operational exploration and engineering cost savings and reduced exploration risks through improved geological mapping. Land and ocean remote sensing satellite systems under development for the 1990's by the United States, France, Japan, Canada, ESA, Russia, China, and others, will significantly increase our ability to explore for, develop, and manage energy and mineral resources worldwide. A major difference between these systems is the “Open Skies” and “Non-Discriminatory Access to Data” policies as have been practiced by the U.S. and France and the restrictive nationalistic data policies as have been practiced by Russia and India. Global exploration will use satellite remote sensing to better map regional structural and basin-like features that control the distribution of energy and mineral resources. Improved sensors will better map lithologic and stratigraphic units and identify alteration effects in rocks, soils, and vegetation cover indicative of undiscovered subsurface resources. These same sensors will also map and monitor resource development. The use of satellite remote sensing data will grow substantially through increasing integration with other geophysical, geochemical, and geologic data using improved geographic information systems (GIS). International exploration will focus on underdeveloped countries rather than on mature exploration areas such as the United States, Europe, and Japan. Energy and mineral companies and government agencies in these countries and others will utilize available remote sensing data to acquire economic intelligence on global resources. If the “Non-Discriminatory Access to Data” principle is observed by satellite producing countries, exploration will remain competitive “on the ground”. In this manner, remote sensing technology will continue to be developed to better explore for and manage the world's needed resources. If, however, satellite producing countries follow the Russian and Indian lead and restrict civil satellite data as tools of their national security and economic policies, remote sensing technology may become internationally competitive in space, redundant, prohibitively expensive, and generally unavailable to the world community.

Security implications of remote sensing

Major technical advances in remote sensing have developed sophisticated systems with both extensive military and civilian applications. Not only the USA and USSR, but a growing number of other countries such as China, France, India and Japan are actively engaged in remote-sensing R&D. This article reviews the capabilities of civilian satellite technologies and programmes of various nations, and examines the implications for national and international security. Many states are concerned about the commercial availability of data on their economic resources and national security-related activities. A particular problem is the possible misinterpretation of remotely-sensed data.