A deployable mast for solar sails in the range of 100–1000 m

The purpose of this paper is to introduce a new deployable mast design that may provide a means to scale up solar sails to very large dimensions. The paper describes the basic analytical approach for truss beams, compares this new design with the state-of-art truss used in NASA’s solar sail development work, and provides analyses of novel applications enabled by the mast design.     

Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI): Instrument Design and Calibration

The Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument was built for launch and operation on the NASA Ionospheric Connection Explorer (ICON) mission. The instrument was designed to measure thermospheric horizontal wind velocity profiles and thermospheric temperature in altitude regions between 90 km and 300 km, during day and night. For the wind measurements it uses two perpendicular fields of view pointed at the Earth’s limb, observing the Doppler shift of the atomic oxygen red and green lines at 630.0 nm and 557.7 nm wavelength. The wavelength shift is measured using field-widened, temperature compensated Doppler Asymmetric Spatial Heterodyne (DASH) spectrometers, employing low order échelle gratings operating at two different orders for the different atmospheric lines. The temperature measurement is accomplished by a multichannel photometric measurement of the spectral shape of the molecular oxygen A-band around 762 nm wavelength. For each field of view, the signals of the two oxygen lines and the A-band are detected on different regions of a single, cooled, frame transfer charge coupled device (CCD) detector. On-board calibration sources are used to periodically quantify thermal drifts, simultaneously with observing the atmosphere. The MIGHTI requirements, the resulting instrument design and the calibration are described.     

Multiple sensor geocoded data

The problem of integrating remotely sensed images acquired from different sensor systems is primarily associated with their registration into a common reference projection. This registration problem has to be considered not only between the image data themselves but also with other data already existing in various geographical data bases.The advent of the second generation of earth observation satellites is emphasizing this situation by providing imagery in different geometric configurations. Images will be acquired from many sensors at different spatial resolutions (LANDSAT MSS and TM, SPOT HRV MLA and PLA) on different dates and modes (panchromatic, multispectral, nadir and off-nadir).In order to provide image data in a geometric format compatible with the Canadian National Topographic System, Canada is developing a Multi-Observational Satellite Image Correction System (MOSAICS) that will provide geocoded data resampled into a common reference projection. This paper presents the characteristics of the geocoded products with examples from multiple sensors and different dates, and addresses the processing requirements of the satellite ground station. It also illustrates the use of digital processing techniques to derive digital elevation information from geocoded stereo imagery.     

Civilizations and Sea Level Change

Climate and sea level changes have been relatively stable for the last few centuries. The delicate balance between global and oceanic systems, however, may be altered due to the increased warming of the earth's average surface temperature. A few degrees increase could cause a 15-17 cm sea level rise by the year 2000, resulting in wide spread flooding of low lying areas. Recent studies indicate the global sea level is rising and extensive coastal flooding is anticipated. If these changes continue through the next century, we may be faced with a loss of our present culture. Oscillating sea levels since the late Pleistocene at times have left the floors of the continental margins and inland seas exposed, increasing the total earth's land surface by 8%. It was during these events that North America and island refugia including England, Indonesia, Japan and Australia were invaded and colonized by man. However, the swinging sea levels and shoreline displacements of as much as 120 m per year must have been very disruptive to the inhabitants of the coastal region and evidence of their cultures must have eroded away due to the relentless cycle of the coastal processes.