New-generation Satellite Research Articles

A preliminary synthesis of major scientific results during the SALSA program

The objective of this paper is to provide an overview of the primary results of the Semi-Arid Land–Surface–Atmosphere (SALSA) Program in the context of improvements to our overall understanding of hydrologic, ecologic, and atmospheric processes and their interactions in a semi-arid basin. The major findings and future research needs associated with the different core components of the program are emphasized. First, remote-sensing investigations are discussed, especially those directed toward taking full advantage of the capabilities of the new generation of satellites (ERS2/ATSR2, VEGETATION, LANDSAT7, NASA-EOS). Second, we discuss parameterization of the water and energy fluxes in arid and semi-arid regions, with special emphasis on methods to aggregate these fluxes from patch scale to grid scale. Third, we address the issues related to grassland ecology and competition for water between native grass and invasive mesquite species. Fourth, findings related to the interactions between surface water, ground water, and vegetation in a semi-arid riparian system are discussed. Next, an assessment of land use and land cover change over the entire basin over a quarter century is reviewed. Finally, unsolved issues and the needs for further research are outlined.

GPS IIF-the next generation

This paper provides an overview of the next generation of the Global-Positioning System (GPS) space and ground segments as embodied in the GPS Block II follow-on (GPS IIF) program. The GPS IIF program includes the procurement of 33 satellites and the operation and support of the new GPS operational control segment. The program is using the principles of acquisition reform to develop and field a new generation of satellites, support equipment, and software. Performance improvements in GPS signal power, accuracy, and service to civilian users are described. These improvements provide a foundation and, combined with the flexibility of the GPS IIF system, they allow for upgrading the system to even greater capability. The elements of the GPS IIF system are described in significant detail.

Multimedia via Inmarsat

Inmarsat's provision of multimedia services over its current satellites, as well as over a possible new generation of satellites, will enable technologies for support of higher data rates for mobile terminals. Inmarsat's next-generation satellite communications system will extend current capabilities by supporting fully interactive multimedia communications to small portable user terminals.

Productive engineering of predictable embedded real-time systems: the road to maturity

This paper discusses a novel engineering approach to the development of the real-time software embedded on board new-generation satellite systems. The work described in this paper was motivated by the rise of the `cheaper, faster, better' mission paradigm, which challenges the suitability of the current software development process and calls for important enhancements to the resulting on-board product. The engineering approach described in this paper is not only to satisfy the new demands but also to accommodate the onerous constraints resulting from the low power profile available to feed on-board memories and CPUs and the hostility of the execution environment to the use of conventional technology. The paper argues that the proposed approach is as productive and mature as required to enter the standard industrial practice in the domain.

PRACTICAL USES OF EARTH OBSERVATION FOR CIVIL ENGINEERING.

Keywords NPA SATELLITE MAPPING, SMITH SYSTEM ENGINEERING SATELLITES, IMAGES, OBSERVATIONS, USE, CIVIL ENGINEERING, MAPPING, IMAGING, ROUTING, PIPELINES, SURVEYS, GEOLOGICAL, SUBSIDENCE, MONITORING, DATA, MAPS, INFORMATION EARTH... Show All

The Arctic Sea Ice‐Climate System: Observations and modeling

Significant advances are being made in our understanding of the Arctic sea ice‐climate system. The mean circulation of the Arctic sea ice cover is now well defined through analysis of data from drifting stations and buoys. Analysis of nearly 20 years of daily satellite data from optical, infrared, and passive microwave sensors has documented the regional variability in monthly ice extent, concentration, and surface albedo. Advances in modeling include better treatments of sea ice dynamics and thermodynamics, improved atmosphere‐ice‐ocean coupling, and the development of high resolution regional models. Diagnostic studies of monthly and interannual sea ice variability have benefited from better sea ice data and geostrophic wind analyses that incorporate drifting buoy data. Some evidence exists for a small retreat of Arctic sea ice over the last 2 decades, but there are large decadal fluctuations in regional ice extent. Antiphase relationships between ice anomalies in different sectors can be related to changes in atmospheric circulation. Evidence suggests that episodes of significant salinity reduction in the North Atlantic, associated with extensive sea ice in the Greenland Sea, may be a manifestation of a decadal oscillation in the Arctic climate system. Aspects of the Arctic system in need of further attention include the surface energy budget and its variability, particularly with respect to the roles of cloud cover and surface types in summer. Sea ice thickness distribution data remain meager, and there are many unknowns regarding the circulation and hydrologic cycle of the Arctic Ocean and its links to the world ocean. Planned measurements from a new generation of satellites, supported by field programs, will provide much needed data to address these issues.

Remote Monitoring and Control of Water Management Systems, via Satellite

Twenty-five years of experience has proven the high reliability of satellite communications. The creation of the International Maritime Satellite Organisation in 1979 opened the way for development of small satellite terminals for use by individual users. The recent order for a new generation of satellites to serve the needs of this 45-nation co-operative and development of the Standard-C system will enable it to provide a message/data service to small and low cost terminals by 1988. Standard-C will create new opportunities to remotely monitor and control processes regardless of distances from a central operations centre. It will permit those on duty to receive routine reports automatically at fixed intervals and/or when measurements fall outside pre-set limits. In the event of an abnormal situation developing it would be possible for the controller to interrogate the sensors at the site by ‘polling’ at any desired interval. This would enable a process to be continuously monitored and devices or systems remotely controlled as required. Because the satellites provide global coverage vast areas can be monitored and controlled independent of local telephone or microwave links. This may be particularly important in areas where individual sensor sites and their links may be vulnerable to disruption due to the possibility of flooding, landslides, earthquakes, etc. In addition, such a system could be used to control day to day operations of sluice gates, etc. in remote areas and thereby lead to improved water management techniques.

Satellite onboard processing

The prospects for the satellite earth station that can be carried in the briefcase — or even in the pocket— depend very strongly on the processing power of the satellite. A new generation of satellites is emerging which could make the ‘personal earth station’ a reality

The next generation of communications satellites

Telecommunications satellites still act as amplifying relays in space, and will continue to be nonswitching relays for the next five years, forseeable developments mainly concerning access modes and channel quality. However, the development of new techniques, the increase in traffic levels and the necessity of catering for new services will lead to a new generation of satellites that will act as switches as well as relays.