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Statistics compiled from Nimbus-6 temperature retrievals processed during the 18 August-4 September 1975 DST-5, and the 1 February-4 March 1976 DST-6 are addressed. All statistics were compiled from samples of colocated satellite sounding and radiosonde measurements. The colocation window is 222 km in space and 6 hours in time.
The application of the systems engineering process to the planning of the Voyager spacecraft mission is described. The Mission Planning Office prepared guidelines that controlled the use of the project and multimission resources and spacecraft consumables in order to obtain valuable scientific data at an acceptable risk level. Examples of mission planning which are concerned with the design of the Deep Space Network antenna, the uplink window for transmitting computer command subsystem loads, and the contingency and risk assessment functions are presented.
A set of studies was performed to investigate the feasibility of using the Titan III launch vehicle to launch an unmanned prototype HL-20 personnel launch system and, potentially, operational HL-20 missions. The launch of an HL-20 spacecraft on a Titan III poses a unique set of concerns, primarily because the lifting body vehicle is carried on top of the Titan vehicle without a fairing. The Titan III/HL-20 feasibility study addressed the primary vehicle issues of performance, aerodynamics, loads, control and stability, launch availability, and vehicle configuration for the launch of an unmanned HL-20 prototype vehicle. Titan launch operations, launch site systems, and facilities were assessed to determine HL-20 operations compatibility. Additional studies determined the potential launch opportunity and window capabilities of the Titan III for the operational HL-20 mission and the existing Titan III's reliability. The feasibility study determined that the Titan III system, with minor changes, is compatible with the HL-20 vehicle and mission. It could provide nearly daily launch windows for a rendezvous with Space Station Freedom. Titan III reliability, when combined with the HL-20 launch escape system, provides a sufficiently high probability of crew survival to support its consideration as the primary vehicle for HL-20 operational missions.
Transparent conductive thin films are required for a variety of optoelectronic applications: automotive and aircraft windows, and solar cells for space applications. Transparent conductive coatings of indium-tin-oxide (ITO)-magnesium fluoride (MgF2) and aluminum doped zinc oxide (AZO) at several dopant levels are investigated for electrical resistivity (sheet resistance), carrier concentration, optical properties, and atomic oxygen durability. The sheet resistance values of ITO-MgF2 range from 10(exp 2) to 10(exp 11) ohms/square, with transmittance of 75 to 86 percent. The AZO films sheet resistances range from 10(exp 7) to 10(exp 11) ohms/square with transmittances from 84 to 91 percent. It was found that in general, with respect to the optical properties, the zinc oxide (ZnO), AZO, and the high MgF2 content ITO-MgF2 samples, were all durable to atomic oxygen plasma, while the low MgF2 content of ITO-MgF2 samples were not durable to atomic oxygen plasma exposure.
This paper describes a gas turbine simulation system which utilizes the newly developed Java language environment software system. The system provides an interactive graphical environment which allows the quick and efficient construction and analysis of arbitrary gas turbine propulsion systems. The simulation system couples a graphical user interface, developed using the Java Abstract Window Toolkit, and a transient, space- averaged, aero-thermodynamic gas turbine analysis method, both entirely coded in the Java language. The combined package provides analytical, graphical and data management tools which allow the user to construct and control engine simulations by manipulating graphical objects on the computer display screen. Distributed simulations, including parallel processing and distributed database access across the Internet and World-Wide Web (WWW), are made possible through services provided by the Java environment.
Keeping ski goggles from fogging is just one of dozens of uses for anti-fog coating developed at Johnson Space Center to keep spacecraft windows clear before launch. Basic composition of coating includes a liquid detergent, deionized water, an oxygen-compatible, fire resistant oil. Two thin coatings are applied to glass or plastic surface and buffed lightly. Applications include deep sea diving masks, fire protection helmets, eyeglasses, and vehicle windows.
Researchers at NASA Langley Research Center are developing a new electron beam freeform fabrication (EB F(sup 3)) technique to fabricate metal parts. This process introduces metal wire into a molten pool created by a focused electron beam. Potential aerospace applications for this technology include ground-based fabrication of airframe structures and on-orbit construction and repair of space components and structures. Processing windows for reliably producing high quality 2219 aluminum parts using the EB F(sup 3) technique are being defined. The effects of translation speed, wire feed rate, and beam power on the resulting microstructures and mechanical properties are explored. Tensile properties (ultimate tensile strength, yield strength, and elongation) show little effect over the range of processing conditions tested. Basic processing-microstructure-property correlations are drawn for the EB F(sup 3) process.
On April 12, 2002, NASA Administrator Sean O Keefe opened a new window to the future of space exploration with these words in his Pioneering the Future address. Thus began the conceptual framework for structuring the new Education Enterprise. The Agency s mission is to understand and protect our home planet; to explore the universe in search for life; and to inspire the next generation of explorers as only NASA can. In adopting this mission, education became a core element and is now a vital part of every major NASA research and development mission. NASA s call to inspire the next generation of explorers is now resounding throughout the NASA community and schools of all levels all around the country. The goal is to capture student interest, nurture their natural curiosities, and intrigue their minds with new and exciting scientific research; as well as to provide educators with the creative tools they need to improve America s scientific literacy. The future of NASA begins with America s youngest scholars. According to Administrator O Keefe s address, if NASA does not motivate the youngest generation now, there is little prospect this generation will choose to pursue scientific disciplines later. Since embracing Administrator O Keefe s educational mandate over a year ago, NASA has been fully devoted to broadening its roadmap to motivation. The efforts have generated a whole new showcase of thoughtprovoking and fun learning opportunities, through printed material, Web sites and Webcasts, robotics, rocketry, aerospace design contests, and various other resources as only NASA can.
Current state-of-the-art commercial sensors and actuators do not meet many of NASA s next generation spacecraft and instrument needs. Nor do they satisfy the DoD needs for satellite missions, especially micro/nano satellite missions. In an effort to develop advanced optical devices and instruments that meet mission requirements, NASA Langley recently completed construction of a new cleanroom housing equipment capable of fabricating high performance active optic and adaptive optic technologies including deformable mirrors, reconfigurable lenses (both refractive and diffractive), spectrometers, spectro-polarimeters, tunable filters and many other active optic devices. In addition to performance, these advanced optic technologies offer advantages in speed, size, weight, power consumption, and radiation tolerance. The active optic devices described in this paper rely on birefringent liquid crystal materials to alter either the phase or the polarization of the incoming light. Design considerations and performance evaluation results for various NASA applications are presented. Applications presented will include large space telescopes, optical communications, spacecraft windows, coronagraphs, and star trackers. Keywords: Photonics, Adaptive Optics, Tunable Filters, MEMs., MOEMs, Coronagraph, Star Tracker
The inclusive WZ production cross section is measured in proton-proton collisions at a centre-of-mass energy of 13.6 TeV, using data collected during 2022 with the CMS detector, corresponding to an integrated luminosity of 34.7 fb −1 . The measurement uses multileptonic final states and a simultaneous likelihood fit to the number of events in four different lepton flavour categories: eee, ee μ , μμ e, and μμμ . The selection is optimized to minimize the number of background events, and relies on an efficient prompt lepton discrimination strategy. The WZ production cross section is measured in a phase space defined within a 30 GeV window around the Z boson mass, as σ total (pp → WZ) = 55.2 ± 1.2 (stat) ± 1.2 (syst) ± 0.8 (lumi) ± 0.3 (theo) pb. In addition, the cross section is measured in a fiducial phase space closer to the detector-level requirements. All the measurements presented in this paper are in agreement with standard model predictions.
Passive cooling devices take advantage of the partially transparent properties of the atmosphere in the longwave spectral band from 8 to 13 μ m (the so-called “atmospheric window”) to reject radiation to outer space. Spectrally designed thermophotonic devices have raised substantial attention recently for their potential to provide passive and carbon-free alternatives to air conditioning. However, the level of transparency of the atmospheric window depends on the local content of water vapor in the atmosphere and on the optical depth of clouds in the local sky. Thus, the radiative cooling capacity of solar reflectors not only depends on the optical properties of their surfaces but also on local meteorological conditions. In this work, detailed radiative cooling resource maps for the contiguous United States are presented with the goal of determining the best climates for large-scale deployment of passive radiative cooling technologies. The passive cooling potential is estimated based on ideal optical properties, i.e., zero shortwave absorptance (maximum reflectance) and blackbody longwave emittance. Both annual and season-averaged maps are presented. Daytime and nighttime cooling potential are also computed and compared. The annual average cooling potential over the contiguous United States is 50.5 m -2 . The southwestern United States has the highest annual averaged cooling potential, over 70 W m -2 , due to its dry and mostly clear sky meteorological conditions. The southeastern United States has the lowest potential, around 30 W m -2 , due to frequent humid and/or overcast weather conditions. In the spring and fall months, the Arizona and New Mexico climates provide the highest passive cooling potential, while in the summer months, Nevada and Utah exhibit higher potentials. Passive radiative cooling is primarily effective in the western United States, while it is mostly ineffective in humid and overcast climates elsewhere.
This paper develops algorithms for multivariable state-space identification which can be used to estimate models in any operator of interest i.e., delta-rule, shift, Laplace s, etc. The approach is based on the State-Space from Frequency Data (SSFD) algorithm which was designed specifically to eliminate distortions from windowing effects.
Impact sites in glass affect its fracture strength. An analytical model that predicts fracture strength from grey-field polariscope (GFP) readings (photoelastic retardations) has been developed and reported in the literature. The model is suggestive that stress fields, resulting from impact damage, destablizes sites within the glass, which lead to pathways that cause strength degradation. Using data collected from fused silica specimens fabricated from outer window panes that were designed for the space shuttle, the model was tested against four categories of inflicted damage. The damage sites were cored from the window carcasses, examined with the GFP and broken using the ASTM Standard C1499-09 to measure the fracture strength. A correlation is made between the fracture strength and the photoelastic retardation measured at the damage site in each specimen. A least-squares fit is calculated. The results are compared with the predictions from the model. A plausible single-sided NDE damage site inspection method (a version of which is planned for glass inspection in the Orion Project) that relates photoelastic retardation in glass components to its fracture strength is presented.
The detection of gravity waves will open a new window of observation on the universe. Unlike typical observatories, which detect electromagnetic waves traveling through space-time, the Laser Interferometer Space Antenna (LISA) will detect ripples in space-time itself. Science targets include galactic binaries, merging supermassive black holes, intermediate-mass/seed black holes, and cosmological backgrounds. Gravity waves are detected by measuring the strain in space, i.e. the change in distance between a set of masses (test masses or proof masses) separated by a great distance. Ground based detection of gravity waves by Laser Interferometer Gravitational Wave Observatory (LIGO) and other observatories are possible with laser interferometry; hut the relatively short arm length (4 km) and seismic noise limit the measurement band to above 10 Hz on Earth. LISA also uses laser interferometric measurement of the change in distance between test masses, but does it in space. Each LISA spacecraft embodies two test masses. Space allows very long arm lengths (5 million km for LISA) and a very quiet acceleration environment (3.5x10(exp -15) meters per second squared/Hertz (sup 0.5) for LISA), which allows for the detection of gravity wave strains to a best sensitivity of 3x10(exp -24) strain/Hertz (sup 0.5) over the measurement band of 10(exp -4) to 10(exp -1) Hertz for a one-year observation. The LISA mission consists of three spacecraft in heliocentric orbit. The orbits are chosen so that the three spacecraft form a roughly equilateral triangle with its center located at a radius of 1 AU and 20 degrees behind the Earth, as shown. Requirements are placed on the rotational and translational dynamics of each spacecraft to ensure that the proper sensitivity for science measurements can be achieved.
The design and development of high temperature antennas for the space shuttle orbiter are discussed. The antenna designs were based on three antenna types, an annular slot (L-Band), a linear slot (C-Band), and a horn (C-Band). The design approach was based on combining an RF window, which provides thermal protection, with an off-the-shelf antenna. Available antenna window materials were reviewed and compared, and the materials most compatible with the design requirements were selected. Two antenna window design approaches were considered: one employed a high temperature dielectric material and a low density insulation material, and the other an insulation material usable for the orbiter thermal protection system. Preliminary designs were formulated and integrated into the orbiter structure. Simple electrical models, with a series of window configurations, were constructed and tested. The results of tests and analyses for the final antenna system designs are given and show that high temperature antenna systems consisting of off-the-shelf antennas thermally protected by RF windows can be designed for the Space Shuttle Orbiter.
After more than fifty years of space activities, the near-Earth environment is polluted with man-made orbital debris. The collision between Cosmos 2251 and the operational Iridium 33 in 2009 signaled a potential collision cascade effect, also known as the "Kessler Syndrome", in the environment. Various modelling studies have suggested that the commonly-adopted mitigation measures will not be sufficient to stabilize the future debris population. Active debris removal must be considered to remediate the environment. This paper summarizes the key issues associated with debris removal and describes the technology and engineering challenges to move forward. Fifty-four years after the launch of Sputnik 1, satellites have become an integral part of human society. Unfortunately, the ongoing space activities have left behind an undesirable byproduct orbital debris. This environment problem is threatening the current and future space activities. On average, two Shuttle window panels are replaced after every mission due to damage by micrometeoroid or orbital debris impacts. More than 100 collision avoidance maneuvers were conducted by satellite operators in 2010 to reduce the impact risks of their satellites with respect to objects in the U.S. Space Surveillance Network (SSN) catalog. Of the four known accident collisions between objects in the SSN catalog, the last one, collision between Cosmos 2251 and the operational Iridium 33 in 2009, was the most significant. It was the first ever accidental catastrophic destruction of an operational satellite by another satellite. It also signaled the potential collision cascade effect in the environment, commonly known as the "Kessler Syndrome," predicted by Kessler and Cour-Palais in 1978 [1]. Figure 1 shows the historical increase of objects in the SSN catalog. The majority of the catalog objects are 10 cm and larger. As of April 2011, the total objects tracked by the SSN sensors were more than 22,000. However, approximately 6000 of them had yet to be fully processed and entered into the catalog. This population had been dominated by fragmentation debris throughout history. Before the anti-satellite test (ASAT) conducted by China in 2007, the fragmentation debris were almost all explosion fragments. After the ASAT test and the collision between Iridium 33 and Cosmos 2251, the ratio of collision fragments to explosion fragments was about one-to-one. It is expected that accidental collision fragments will further dominate the environment in the future.
Developing an objective field-of-view methodology for studying vehicle window placement has been somewhat difficult. It is not surprising that considerable effort has been directed at specific problems of visibility from vehicles. Aeronautical design engineers know when designing an aircraft cockpit, the pilot must have an adequate view for approaching and landing on an airfield. However, compromise between the ergonomic preference for the largest possible viewing envelope and the practicalities of arranging a structure that is lightweight and strong will always plague the cockpit’s transparent area’s size and shape. The human’s visual sense, when operating any kind of vehicle, is the main source of the vast majority of information needed to drive or fly safely. However, vehicle design can affect a driver’s visual performance for satisfying their need for information. For any vehicle, be it an automobile or a spacecraft, the visibility quantity is the sum total of the visual access to the environment as defined by the window placement of that vehicle. The Alternate Multiple Mission Space Exploration Vehicle (AMMSEV) configuration is much like a large cargo truck where there is no direct visual access to the rear of the vehicle or the rear sides of the vehicle; thus, making the forward and side views of greater importance to the situational awareness of the crew if obstructions are creating visual issues. The National Aeronautics and Space Administration (NASA) tested a new theoretical model for Field-of-View (FOV) of spacecraft windows in NASA’s own Neutral Buoyancy Laboratory (NBL). The NBL is an essential tool for design, testing and development of future space exploration hardware for upcoming NASA operational missions. Using water, with its natural propensity for giving a human the perception of dynamic body motion under a weightless or partial gravity conditions, gives human factors investigators a vigorous space-like environment to study new methods of collecting dynamic field-of-view for future exploration vehicle designs.
Abstract A variational autoencoder (VAE) is a type of unsupervised neural network which is able to learn meaningful data representations in a reduced dimensional space. We present an application of VAE in identifying the operational stability boundary of tokamak plasma discharges. This model was implemented using a dataset of over 3000 discharges from the high beta tokamak-extended pulse (HBT-EP) device. We found the VAE model to be capable of forming a continuous low-dimensional operational space map and identifying the operational boundaries using a specified warning time window. By projecting the operational parameters onto the same reduced space, this provides an intuitive way for the machine operator or an automated control system to perform disruption avoidance using a relevant control actuator as a discharge approaches a boundary. Pre-programmed GPU control experiments were conducted to demonstrate this control technique using HBT-EP’s saddle control coils as a horizontal position actuator, showing the ability to avoid the oncoming disruptive event and extend the duration of the discharge.