SEARCH · Search NASA
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Engineering analyses and trades necessary to identify a preferred laboratory concept which will meet the science requirements were conducted. Results are summarized.
The current plane to provide radio science real-time display capability in response to multimission radio science requirements is described. Topics discussed include the display of Doppler frequency and high-resolution graphical display of all closed-loop radio metric parameters, and spectrum displays of open-loop receiver output.
The reported study represents an extension of an investigation by Harrison et al. (1976). Based on the results of sampling studies, two 98 deg inclined orbits coupled with a 56 deg inclination orbit appear to satisfy the science requirements on both regional and zonal scales. The NOAA sun-synchronous satellites in the TIROS-N series could adequately cover the high latitudes and a satellite having an inclination of 56 deg could provide sampling in the mid and low latitude areas where variations in radiation energetics are most dynamic. Attention is given to studies of time and space coverage, zonal evaluations, a regional analysis, and statistics describing the regional variations of cloud cover. A table is presented with data concerning the uncertainty of monthly mean reflected irradiance due to cloud variability for selected northern hemisphere regions.
A study was conducted to identify problems related to sampling the Earth's radiant energy budget and to define a satellite system with sufficient sampling to satisfy science requirements on global, zonal, and regional scales.
A dual comet (Halley Flyby/Tempel 2 Rendezvous) mission, which is planned to be the first to use the Solar Electric Propulsion System (SEPS), is to be launched in 1985. The purpose of this paper is to describe how the mission design attempts to maximize science return while working within spacecraft and other constraints. Science requirements and desires are outlined and specific instruments are considered. Emphasis is on the strategy for operations in the vicinity of Tempel 2, for which a representative profile is described. The mission is planned to extend about one year past initial rendezvous. Because of the large uncertainty in the comet environment the Tempel 2 operations strategy must be highly adaptive.
An orbital analysis has been performed to define the spatial and temporal coverage capabilities of limb scanning experiments for meeting the science requirements for the upper atmosphere research satellite missions. Results indicate that a combination of solar occultation experiments and limb thermal emission experiments having azimuthal scan capability can provide good temporal and spatial coverage of the earth from a 600-km, 56-deg inclined orbit for the first satellite mission. Using a 70-deg inclined orbit for the second satellite mission will complement the first mission and provide complete global coverage with the two types of experiments.
The mission design for Project Galileo is described. Details are presented on the design of the trajectory from launch through completion of the satellite tour, with emphasis on how this design is influenced both by science requirements on the mission and by the interaction of this design with the various elements of the Project. A number of features contribute to the uniqueness of the mission design for this Project. Among the more salient of these that are described in this paper are the use of numerous planetary or satellite encounters for gravity assisted trajectory shaping, and closely related to this, the threading of a trajectory through the Galilean satellite system which meets the mission objectives with a minimum of propulsive trajectory corrections.
The VOIR mission will be devoted to obtaining synthetic aperture radar images of at least 70% of the Venus surface at resolutions of 600 m/line pair or better. High-resolution spot coverage, nested within the low-resolution data, will be obtained for up to 1% of the surface. Additional investigations will examine the shape and gravitational field of the planet, the character of its interior, the composition and dynamics of its atmosphere, and its interaction with the solar wind. This paper describes the VOIR mission as it is presently planned, and shows how the design of the spacecraft and the mission is responsive to the project science requirements as well as other programmatic constraints. In addition, several of the tradeoffs associated with the evolution of the present VOIR spacecraft and mission plan are reviewed.
The Voyager spacecraft represents the state-of-the-art in proven long-life planetary spacecraft. Like its predecessors, the Voyager system design reflects the influence of mission and science requirements, lifetime considerations, environmental factors, technology readiness, hardware availability, and hardware cost. This paper presents the Voyager hardware and software system designs within the context of these design drivers. Major departures from the 'baseline design' are discussed revealing the underlying factors that shaped the final design. Finally, with the benefit of 5 years of test and inflight operational experience, a critical assessment of the design and design methods is made and suggestions are offered to improve similar future efforts.
The design of Galileo's tour of Jupiter's Galilean satellites is discussed. The Galileo mission is reviewed, and the gravity-assist trajectory design is described. Attention is given to mission constraints and science requirements, several tour design strategies, and a strawman satellite tour. The software used to design a satellite tour is examined.
Meeting the identified needs of Earth science requires approaching EOS as an information system and not simply as one or more satellites with instruments. Six elements of strategy are outlined as follows: implementation of the individual discipline missions as currently planned; use of sustained observational capabilities offered by operational satellites without waiting for the launch of new mission; put first priority on the data system; deploy an Advanced Data Collection and Location System; put a substantial new observing capability in a low Earth orbit in such a way as to provide for sustained measurements; and group instruments to exploit their capabilities for synergism; maximize the scientific utility of the mission; and minimize the costs of implementation where possible.
The instrumentation problems associated with the measurement of soil moisture with a meaningful spatial and temperature resolution at a global scale are addressed. For this goal only medium term available affordable technology will be considered. The study while limited in scope, will utilize a large scale antenna structure, which is being developed presently as an experimental model. The interface constraints presented by a singel Space Transportation System (STS) flight will be assumed. Methodology consists of the following steps: review of science requirements; analyze effects of these requirements; present basic system engineering considerations and trade-offs related to orbit parameters, number of spacecraft and their lifetime, observation angles, beamwidth, crossover and swath, coverage percentage, beam quality and resolution, instrument quantities, and integration time; bracket the key system characteristics and develop an electromagnetic design of the antenna-passive radiometer system. Several aperture division combinations and feed array concepts are investigated to achieve maximum feasible performacne within the stated STS constraints.
Attention is given to a spectrometer design candidate for the X-ray Multi-Mirror observatory, being planned by the European Space Agency as a long-lived large-area array of telescopes. The science requirement of moderate resolution spectroscopy in a two octave region with extremely high throughput leads to the use of grazing incidence reflection gratings. It is noted that the sensitivity of the instrument is sufficient to permit the first spectral detection of soft X-ray features in external galaxies.
Plans are underway at NASA Goddard to develop a moderate-resolution (0.5-1.0-km) imaging spectrometer with 104 spectral bands in the range from 0.4 to 14.2 microns for use as a NASA facility aboard the Space Station Earth Observation System. Science requirements call for the system to image the earth's surface every 2 d for a period of 10 yr, using two electrooptic sensors. MODIS-T (tilt) has 64 10-nm-wide channels in the 400-1000-nm range. The system has 5-cm-diameter optics, scans + or - 45 deg, and can be pointed + or - 60 deg along track. Calculated S/N is in excess of 800:1 near 400 nm. MODIS-N (nadir) scans + or - 45 deg about nadir with 12 500-m- and 28 1000-m-resolution channels, including two polarization channels and 14 thermal-IR channels. With 20-cm-diameter optics the calculated S/N of the majority of the reflected solar bands is over 1000:1. NETD values for the thermal bands are on the order of 0.1-0.2 K at 300 K. Combined MODIS-T and MODIS-N data rates are 8.3 Mb/s in daylight and 1.5 Mb/s at night, resulting in a total of 360 Gb/d.
The high-resolution imaging spectrometer (HIRIS) is an Earth Observing System (EOS) sensor developed for high spatial and spectral resolution. It can acquire more information in the 0.4 to 2.5 micrometer spectral region than any other sensor yet envisioned. Its capability for critical sampling at high spatial resolution makes it an ideal complement to the MODIS (moderate-resolution imaging spectrometer) and HMMR (high-resolution multifrequency microwave radiometer), lower resolution sensors designed for repetitive coverage. With HIRIS it is possible to observe transient processes in a multistage remote sensing strategy for Earth observations on a global scale. The objectives, science requirements, and current sensor design of the HIRIS are discussed along with the synergism of the sensor with other EOS instruments and data handling and processing requirements.
Conceptual designs and programmatics of the space station accommodations for the Life Sciences Research Facilities (LSRF) are presented. The animal ECLSS system for the LSRF provides temperature-humidity control, air circulation, and life support functions for experimental subjects. Three ECLSS were studied. All configurations presented satisfy the science requirements for: animal holding facilities with bioisolation; facilities interchangeable to hold rodents, small primates, and plants; metabolic cages interchangeable with standard holding cages; holding facilities adaptable to restrained large primates and rodent breeding/nesting cages; volume for the specified instruments; enclosed ferm-free workbench for manipulation of animals and chemical procedures; freezers for specimen storage until return; and centrifuge to maintain animals and plants at fractional g to 1 g or more, with potential for accommodating humans for short time intervals.
The objectives of the Telescience Testbed Pilot Program (TTPP) are discussed. The purpose of the TTPP, which involves 15 universities in cooperation with various NASA centers, is to demonstrate the utility of a user-oriented rapid prototyping testbed approach to developing and refining science requirements and validation concepts and approaches for the information systems of the Space Station era and beyond. It is maintained that the TTPP provides an excellent environment, with low programmatic schedule and budget risk, for testing and evaluating new operations concepts and technologies.
Through the Microgravity Science and Applications Division (MSAD) of the Office of Space Science and Applications (OSSA) at NASA Headquarters, a program entitled, Advanced Technology Development (ATD) was promulgated with the objective of providing advanced technologies that will enable the development of future microgravity science and applications experimental flight hardware. Among the ATD projects one, Microgravity Combustion Diagnostics (MCD), has the objective of developing advanced diagnostic techniques and technologies to provide nonperturbing measurements of combustion characteristics and parameters that will enhance the scientific integrity and quality of microgravity combustion experiments. As part of the approach to this project, a workshop was held on July 28 and 29, 1987, at the NASA Lewis Research Center. A small group of laser combustion diagnosticians met with a group of microgravity combustion experimenters to discuss the science requirements, the state-of-the-art of laser diagnostic technology, and plan the direction for near-, intermediate-, and long-term programs. This publication describes the proceedings of that workshop.