Implications of previous space commercialization experiences for the reusable launch vehicle

In evaluating the prospects for the development of a commercially viable RLV, it may be useful to examine ’lessons learned‘ from previous space commercialization efforts– both those that succeeded and those that did not. It can be argued that several distinct streams of market and technological development may have to converge for successful commercialization of space systems to occur. Factors influencing the prospects for commercialization include the size and growth rate of the potential customer base, the extent to which a governmental customer exists to underpin the market, the development of associated ’value-added‘ markets, the stability of governmental policies, the availability of enabling or enhancing infrastructure, the levels of technological and business risk, and the degree to which competitive markets exist. This paper examines two previous space commercialization experiences, evaluates the relative importance of the various factors that influence the prospects for success of commercialization efforts, and assesses the implications of those factors for the commercial viability of the proposed RLV.     

Safety issues in SPS wireless power transmission

The use of wireless power transmission in Space Solar Power (SSP) activities creates significant policy issues regarding the beam right-of-way. There will not be a single beam, there may well be hundreds of beams for economical systems. Are some or all of these power beams to be afforded priorities of space for unobstructed power delivery, or must the beaming systems be designed to be capable of detecting any and all potential beam interceptions and appropriately responding? The repeated interruptions for guaranteed safety of transit for freely moving air and space traffic are of great consequence. The safety issues are critical, but the implications for equipment transient protection, energy storage system costs and the quality of power delivery service are also significant for wireless power transmission economics. A scenario of precursor wireless power transmission developments leading up to and including SSP applications will be used to frame and to discuss the beamed power technology implications and policy issues.     

Solar UV radiation variations and their stratospheric and climatic effects

NIMBUS-7 SBUV measurements of the short-term solar UV variations caused by solar rotation and active-region evolution have determined the amplitude and wavelength dependence for the active-region component of solar UV variations. Intermediate-term variations lasting several months are associated with rounds of major new active regions. The UV flux stays near the peak value during the current solar cycle variation for more than two years and peaks about two years later than the sunspot number. NIMBUS-7 measurements have observed the concurrent stratospheric ozone variations caused by solar UV variations. There is now no doubt that solar UV variations are an important cause of short- and long-term stratospheric variations, but the strength of the coupling to the troposphere and to climate has not yet been proven.     

Human Factors R&D Requirements for Future Aerospace Cockpit Systems

Cockpits are rapidly changing from dedicated instruments to multifunction displays, integrated controls, and computer controlled subsystems. Solid-state displays, voice recognition, and artificial intelligence are just a few of the emerging technologies that will help the pilot perform his mission in the future. Early investigations involving mission analysis, sensor data, software development, and evaluations will be required to insure total integration. These new technologies will require extensive human factors research in the areas of anthropometry, displays, controls, human/computer interface, automation, and workload assessment to support the integration process. This research will help provide weapons systems that have increased survivability and reduced pilot workload. This paper addresses some of the human factors research that will be needed to help develop future cockpit systems. It also reviews the basic evolution of the crew station and some of the emerging technologies that will drive human factors research in the 1990s. In the past, crew systems were designed to provide each aircraft function with a corresponding instrument display, such as airspeed indicator, altimeter, attitude direction indicator, vertical velocity indicator, etc. The bulk of the information had to be integrated by the pilot. Present systems are in a state of transition. We are rapidly moving from individual instruments to multifunction displays. The C-17, HH-60, F-15E, B-1B, F-111D, and F-16C/D aircraft use multifunction, cathode-ray tube displays, some of which are color. Another trend is the continued increase in the use of integrated controls.     

Understanding magnetotail current sheet meso-scale structures using MHD simulations

Recent Cluster observations have strongly supported the existence of meso-scale structure in the magnetotail current sheet. In our study, a magnetohydrodynamic simulation event study exhibited current sheet behavior comparable to that seen in the Cluster observations. Geotail and DoubleStar observations also show that the simulation is providing a realistic representation of the magnetosphere during the period of interest; that is, when the current sheet evidently becomes bifurcated. The magnetohydrodynamic simulation allows us to place the local observations into a global contest. It shows that the observations can be explained in terms of localized reconnection tailward of the Cluster location and the formation of a flux rope nearby. The simulation also features wave-like structure across the current sheet.     

Space Telescope observations of aurorae on the giant planets

For the distant giant planets, Uranus and Neptune, the observation of aurorae may be the best astronomical technique for the detection of planetary magnetic fields, with implications for the structure and composition of their interiors. Aurorae may be detected by emssion of H I Ly α (1216 Å) and by H₂ bands near 1600 Å. The latter are important for very faint aurorae because there is essentially no planetary, interplanetary or geocoronal scattering of sunlight to contaminate the signal. For Uranus, present IUE results suggest the presence of a strong aurora at Ly α, but the background and instrument noise levels are very high compared to the apparent signal. At 1600 Å, the IUE instrument noise renders the H₂ emission bands on Uranus marginal at best. No aurora has yet been observed on Neptune. For Jupiter, where the existence and general characteristics of the magnetic field are well established, there is disagreement between ground-based infrared and space-borne ultraviolet observations of the location of the aurorae. For all four giant planets, Space Telescope can improve upon the quality of current optical observations. For spectroscopy, the low resolution mode of the High Resolution Spectrograph (HRS) is particularly well suited to auroral observations because of its spectral range, adequate resolution and high sensitivity. For ultraviolet imaging through appropriate filters, the ST spatial resolution, expected to be of order 5 hundredths of an arc second, is also well suited to determine the spatial properties of the aurorae.     

Measurements of solar total irradiance and its variability

The development of electrically self calibrated cavity pyrheliometric instrumentation that occurred in the early 20th century provided the technological base for experiments to detect variability of the solar total irradiance. Experiments from ground based observatories, aircraft and balloons during the 1st half of the 20th century were unable to achieve sufficient accuracy or long term precision to unambiguously detect irradiance variations of solar origin. Refinements in pyrheliometric technology during the 1960's and 1970's and the accessibility of extended experimental opportunities above the Earth's atmosphere in recent years have provided the first direct observations of solar total irradiance variability and provided the cornerstone observations of a long term database on solar irradiance. A program of solar irradiance monitoring has evolved to sustain the database over at least 22 years, corresponding to a single cycle of solar magnetic activity, and the shortest well identified cycle of climate variation. Direct links between total irradiance variations, solar magnetic activity and the solar global 5 min oscillation phenomena have been derived from recent space flight observations by the SMM/ACRIM I experiment.     

Range Contamination and Its Effect on Measurements

Increased sensitivity and dynamic range of the instrumental techniques used in conjunction with experiments on ballistic ranges have brought to the fore many problems arising from contamination in the ranges themselves. This is seldom discussed when experimental results are presented but is frequently the controlling limitation on the accuracy of the measurements. The authors discuss contamination due to dirt and debris resultant from gun operation, gaseous impurities, and projectile-borne impurities as they have occurred at the Re-entry Simulating Range of Lincoln Laboratory. The effects of these contaminants on measurements are discussed and illustrated, and measures for controlling them are outlined. Finally, a particular range operation is described from the standpoint of impurity control.