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101.
Richard S. Mussakowski 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(8):103-107
This paper describes a procedure for detecting and mapping changes in vegetation cover using LANDSAT digital analysis techniques, and demonstrates how the procedure can be used as an aid to environmental monitoring. Digital image analysis is used to perform a historical comparison, and a computerized colour plotter is used to map the changes in vegetation. 相似文献
102.
Adigun Ade Abiodun Richard S. Odingo 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(7):79-84
Through space applications, a number of social and economic programmes in education, communications, agro-climatology, weather forecasting and remote sensing are being realized within the African continent. Regional and international organizations and agencies such as the African Remote Sensing Council, the Pan-African Telecommunication Union and the United Nations system have been instrumental in making Africa conscious of the impact and implications of space science and technology on its peoples.The above notwithstanding, discernible interests in space research, to date, in Africa, have been limited to the work on the solar system and on interplanetary matters including satellite tracking, and to the joint African-Indian proposal for the establishment of an International Institute for Space Sciences and Electronics (INISSE) and the construction, in Kenya, of a Giant Equatorial Radio Telescope (GERT).During this “Transport and Communications Decade in Africa,” Africa's basic space research efforts would need to initially focus on the appropriateness, modification and adaptation of existing technologies for African conditions with a view to providing economic, reliable and functional services for the continent. These should include elements of electronics, communications, structural and tooling industries, and upper-atmosphere research. The experience of and collaborative work with India, Brazil and Argentina, as well as the roles of African scientists, are examined. 相似文献
103.
104.
Whitten Gary Roberts Arthur Sadowski Henry Hein Richard 《Aerospace and Electronic Systems Magazine, IEEE》1986,1(10):8-18
In this paper we discuss a simple temperature-driven segmentation technique that can be used for autonomous terminal guidance of anti-tank munitions. A ratio between two images from different IR bands is taken to form an emissivity independent image that is a function of temperature only. Size and temperature discrimination can then be used to find hot spots of interest. Candidate targets are segmented from the image about the points of interest using an.algorithm that finds all regions in multi-region objects and does not require a priori intensity information. Size and gross shape features are used to determine if the segmented objects are to be classified as targets. The key to this approach is the initial hot spot extraction. The temperature dependent ratio image allows quick and confident screening of the entire field of view, so that only the regions of interest require further processing. The described techniques effectively found tanks in the presence of common battlefield clutter when used with synthetic IR imagery provided by Georgia Tech Research Institute. The simplicity, effectiveness and potential speed of this technique make it ideal for autonomous guidance of expendable anti-tank weapons, especially where only low resolution IR imagery is available. 相似文献
105.
Elliott Coleshill Layi Oshinowo Richard Rembala Bardia Bina Daniel Rey Shelley Sindelar 《Acta Astronautica》2009,64(9-10):869-874
The Special Purpose Dexterous Manipulator (SPDM), known as “Dextre”, is currently slated to launch in February 2008 for deployment on the International Space Station (ISS) as the final component of Canada's Mobile Servicing System (MSS). Dextre's primary role on the Space Station is to perform repair and replacement (R&R) maintenance tasks on robotically compatible hardware such as Orbital Replaceable Units (ORUs), thereby eventually easing the burden on the ISS crew.This burden on the on-orbit crew translates practically into crew time being a limited resource on the ISS, and as such, finding ways to assist the crew in performing their tasks or offloading the crew completely when appropriate is a bonus to the ISS program. This is already accomplished very effectively by commanding as many non-critical robotics tasks as possible, such as powering up and free-space maneuvering of the Space Station Remote Manipulator System (SSRMS), known as “Canadarm2”, from the Ground.Thus, beyond its primary role, and based on an increasing clarity regarding the challenges of external maintenance on the ISS, Dextre is being considered for use in a number of ways with the objective of improving ISS operations while reducing and optimizing the use of crew time through the use of ground control for various tasks, pre-positioning hardware, acting as a temporary storage platform to break an Extra Vehicular Activity (EVA) day into manageable timelines, and extending the physical reach and range of the Canadarm2.This paper discusses the planned activities and operations for Dextre an rationale for how these will help optimize the use of crew resources on the ISS. 相似文献
106.
Christopher J. Mertens James M. Russell III Martin G. Mlynczak Chiao-Yao She Francis J. Schmidlin Richard A. Goldberg Manuel López-Puertas Peter P. Wintersteiner Richard H. Picard Jeremy R. Winick Xiaojing Xu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) experiment is one of four instruments on NASA’s Thermosphere–Ionosphere–Energetics and Dynamics (TIMED) satellite. SABER measures broadband infrared limb emission and derives vertical profiles of kinetic temperature (Tk) from the lower stratosphere to approximately 120 km, and vertical profiles of carbon dioxide (CO2) volume mixing ratio (vmr) from approximately 70 km to 120 km. In this paper we report on SABER Tk/CO2 data in the mesosphere and lower thermosphere (MLT) region from the version 1.06 dataset. The continuous SABER measurements provide an excellent dataset to understand the evolution and mechanisms responsible for the global two-level structure of the mesopause altitude. SABER MLT Tk comparisons with ground-based sodium lidar and rocket falling sphere Tk measurements are generally in good agreement. However, SABER CO2 data differs significantly from TIME-GCM model simulations. Indirect CO2 validation through SABER-lidar MLT Tk comparisons and SABER-radiation transfer comparisons of nighttime 4.3 μm limb emission suggest the SABER-derived CO2 data is a better representation of the true atmospheric MLT CO2 abundance compared to model simulations of CO2 vmr. 相似文献
107.
James C. Leary Richard F. Conde George Dakermanji Carl S. Engelbrecht Carl J. Ercol Karl B. Fielhauer David G. Grant Theodore J. Hartka Tracy A. Hill Stephen E. Jaskulek Mary A. Mirantes Larry E. Mosher Michael V. Paul David F. Persons Elliot H. Rodberg Dipak K. Srinivasan Robin M. Vaughan Samuel R. Wiley 《Space Science Reviews》2007,131(1-4):187-217
The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was designed and constructed to withstand the harsh environments associated with achieving and operating in Mercury
orbit. The system can be divided into eight subsystems: structures and mechanisms (e.g., the composite core structure, aluminum
launch vehicle adapter, and deployables), propulsion (e.g., the state-of-the-art titanium fuel tanks, thruster modules, and
associated plumbing), thermal (e.g., the ceramic-cloth sunshade, heaters, and radiators), power (e.g., solar arrays, battery,
and controlling electronics), avionics (e.g., the processors, solid-state recorder, and data handling electronics), software
(e.g., processor-supported code that performs commanding, data handling, and spacecraft control), guidance and control (e.g.,
attitude sensors including star cameras and Sun sensors integrated with controllers including reaction wheels), radio frequency
telecommunications (e.g., the spacecraft antenna suites and supporting electronics), and payload (e.g., the science instruments
and supporting processors). This system architecture went through an extensive (nearly four-year) development and testing
effort that provided the team with confidence that all mission goals will be achieved.
Larry E. Mosher passed away during the preparation of this paper. 相似文献
108.
Guhathakurta Madhullika Sittler Ed Fisher Richard Kucera Theresa Gibson Sarah McComas Dave Skoug Ruth 《Space Science Reviews》2001,97(1-4):45-50
The large-scale coronal magnetic fields of the Sun are believed to play an important role in organizing the coronal plasma
and channeling the high and low speed solar wind along the open magnetic field lines of the polar coronal holes and the rapidly
diverging field lines close to the current sheet regions, as has been observed by the instruments aboard the Ulysses spacecraft from March 1992 to March 1997. We have performed a study of this phenomena within the framework of a semi-empirical
model of the coronal expansion and solar wind using Spartan, SOHO, and Ulysses observations during the quiescent phase of the solar cycle. Key to this understanding is the demonstration that the white
light coronagraph data can be used to trace out the topology of the coronal magnetic field and then using the Ulysses data to fix the strength of the surface magnetic field of the Sun. As a consequence, it is possible to utilize this semi-empirical
model with remote sensing observation of the shape and density of the solar corona and in situ data of magnetic field and
mass flux to predict values of the solar wind at all latitudes through out the solar system. We have applied this technique
to the observations of Spartan 201-05 on 1–2 November, 1998, SOHO and Ulysses during the rising phase of this solar cycle and speculate on what solar wind velocities Ulysses will observe during its polar passes over the south and the north poles during September of 2000 and 2001. In order to do
this the model has been generalized to include multiple streamer belts and co-located current sheets. The model shows some
interesting new results.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
109.
At the beginning of the GEOS lifetime, some attempts have been made for taking advantage of the passes over Alaska. GEOS was then commanded in a fixed mode and the corresponding telemetry data were recorded at the NASA stations. For two passes over Jim Creek (48°2N–121°9W) where a powerful VLF transmitter (f
0 = 18.6 kHz) is located, GEOS was put in a specific mode in order to study the magnetospheric electromagnetic field in the vicinity of f
0. The results of one pass (June 11, from 0755 UT) are presented here.During this pass, a strong enhancement of all the e.m. components at f
0 has been observed for a specific period of time, when GEOS was very near to the exact conjugacy with NKL. The distance, as measured on the ground, over which the signal was above -6 dB from the maximum is of the order of 800 km. During the corresponding period of time (0740–0750 UT), the satellite altitude varied between 8000 and 6000 km. The magnetospheric region where the signal is strong appears to be structured, as if there were many ducts.Preliminary results concerning the polarization characteristics of the signal are presented. In the absence of precise measurements of these characteristics, the comparison between the electric and magnetic components of the received signal is not easy to interpret. An examination of the onboard computed correlograms (in the frequency range from f
0 -0.6 kHz to f
0 +3.3 kHz) shows that, for this pass, no VLF emissions were triggered by NKL, at the altitude of the satellite. 相似文献
110.
Space Science Reviews - Meso-scale auroral forms, such as poleward boundary intensifications, streamers, omega bands, beads and giant undulations, are manifestations of dynamic processes in the... 相似文献