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Thermal control materials of different types are being used on the spacecraft for temperature control viz. Thermal control tapes, Thermal control paints, Anodised surfaces and Optical solar reflectors. This paper covers the measurement of emittance at different temperatures on various Optical Solar Reflectors ( OSR ) both rigid and flexible types. The rigid OSRs evaluated are OCLI - USA, PPE - UK and ISRO - INDIA. The flexible OSR is from SHELDAHL - USA. The emittance of the OSRs were measured in the temperature range 223K - 373K using steady state calorimetric method. Measurements were done on a square sample with OSRs affixed on each face. The sample has a built in heater and an evacuated low temperature radiation receiver is used for the test environment. Experimental results, temperature dependence of the total hemispherical emittance relation for each of these OSRs and error estimation are presented in this paper.

This paper presents a summary of the design, development, and ground verification of the BETSU (Brilliant Eyes Thermal Storage Unit) experiment. The BETSU utilizes 2-methyl pentane as a 120 K PCM (Phase Change Material) and will be flown on board the Shuttle in early 1994. There has been very limited experience with the space flight of cryogenic phase change materials. Space applications for a cryogenic TSU include the storage of energy for the cooling of temperature sensitive sensor components such as focal planes, optics, mirrors, and telescopes. Based on ground test data, trade studies were performed which show the significant weight and cost benefits of the BETSU technology.

Joining of a PdCr Strain Gage with a Hastelloy X carrier shim to Inconel by a rapid infrared processing technique has been investigated at 1150 °C using a nickel based brazing alloy AMS 4777, Ni-7Cr-3Fe-3.2B-4.5Si-.06C in wt%. The effects of the infrared joining parameters on the joint and base material microstructure, joint shear strength, and delamination tendency of the PdCr gage was investigated. Results show that the joint shear strength is as high as 503 MPa when processed at approximately 1150 °C for 120 seconds. Microstructural examinations of the joint with both an optical microscope and a scanning electron microscope indicate that good wetting exists between the brazing alloy with both the Hastelloy X and Inconel 718. And, the Hastelloy X and Inconel 718 exhibits no noticeable change in microstructure due to the rapid processing cycle of the infrared heating process while the stabilized PdCr wire gage shows little change in resistance.

Analytical predictions and laboratory measurements were made for the relative total temperature experienced at the tip diameter of a radial-inflow turbine used in an air turbine starter (ATS). The predictions showed that at freerun conditions the blade tip temperature would be significantly higher than the turbine inlet temperature. Tests to confirm this prediction were performed on an ATS modified to accept an optical pyrometer. The pyrometer was focused on the suction side of the blade at the tip radius. Blade temperature measurements conducted at the maximum attainable speed of the ATS verified the prediction to be within the error of the pyrometer measuring system.

Measurements of the gas state properties in hypersonic propulsion system research present unique problems demanding unconventional diagnostic measurement system design solutions. To resolve transient flowfield structures in these high-speed flows, the diagnostic instruments must have high spatial (on the order of 1 mm) and high temporal (on the order of nanoseconds) resolution. These requirements generally demand implementation of nonintrusive techniques. A review is given of nonintrusive techniques, which have been applied to flowfield diagnostics, including Planar Laser Induced Fluorescence (PLIF), Raman Spectrometry, Coherent Anti-Stokes Raman Spectrometry (CARS), and Rayleigh Scattering. A discussion is given of issues associated with the selection of equipment for PLIF and Raman systems, and of lessons learned in their application.

The Thermal Infrared Radiometer (TIR) is part of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) complement of instruments to be flown on NASA's Earth Observing System (EOS) spacecraft. ASTER'S function is to measure atmospheric and terrestrial optical and thermal emissions. TIR provides coverage of the long wave emissions and utilizes several independent thermal control elements to support the exacting thermal requirements of the optical train and electronic assemblies. The widely differing temperature ranges and narrow control bands of the instrument components dictate the need for a combination of active and passive thermal control techniques. The very low temperature required of the thermal emission detector using a Stirling cycle cooler, contrasts with the moderate temperatures needed by the optical train and blackbody. These components are cooled by uniquely configured remote radiators and thermostatically controlled heaters.

On-board, tactical airborne sensor systems perform functions such as target acquisition, track, designation, identification, recognition, threat warning, threat count, missile launch detection and ground mapping in support of situation awareness, self-defense, navigation, target attack, weapon support and reconnaissance. Next generation tactical aircraft in development want those functions performed by sensor suits which exploit modular avionics concepts; exhibit low signature and enhanced stealthiness; have increased availability through increased functional redundancy; and are easy and less costly to maintain. Integrated IR sensors incorporating modular avionics concepts can satisfy those needs. Current IR systems for airborne tactical applications are packaged in either aftermarket pod mounted configurations or in chin mounted protuberances.

Solar flares which produce significant numbers of energetic protons are accompanied by optical, radio and x-ray emissions. Thus the capability for providing early warning of solar proton events (SPEs) is possible if the particle fluxes can be correlated with the electromagnetic signatures from the sun. We have continued to develop and refine the correlations between the proton fluxes in the SPE's and their electromagnetic emissions. Data from over most of solar cycle 21 and the early portion of cycle 22 have been used to extend our data base and improve the correlations between peak proton fluxes and the x-ray fluences which arrive at the earth earlier than the protons. A simple relationship has been derived between the probability of occurrence of an SPE and the observed x-ray fluence.

Laser Velocimetry (LV) is often utilized as an off-the-shelf nonintrusive measurement technique for low speed, steady state flows. However, in complex, supersonic flows, the application of LV becomes highly specialized. Setups must often contend with limited optical access, poor signal-to-noise ratios, and limited tunnel run times. Furthermore, seeding particles must survive large ranges of flow temperatures and pressures, and extensive data analysis and interpretation are required to ascertain whether measured particle velocities are representative of the fluid flow. Several examples of LV studies in the supersonic regime demonstrate recent advancements and the current state-of-the-art of this measurement technique. Results are included from three wind tunnel facilities, operating at freestream Mach numbers of 1.9, 3, and 6, and track an evolution of applications from flat plate boundary layers to the complex flowfield of a supersonic inlet.

Aerodynamics plays a major role in the design of all kinds of vehicles throughout automotive history. Initially the main topic under investigation was the aerodynamic drag reduction to achieve high-energy efficiency, however in the late ‘60s the vertical aerodynamic forces gained traction, particularly in high performance cars. The automotive market usually treats design, aerodynamics and vehicle dynamics in different departments. This paper proposes an integrated approach for the aerodynamics development in which a sport car is defined as reference vehicle. The objective of the concurrent engineering operation is to control the aerodynamic forces by implementing active surfaces control finally improving vehicle lap time. The vehicle dynamics analysis is carried out in cooperation with vehicle aerodynamics in order to perform the hardware and software design of the active system.

This paper focuses on the design, construction, preliminary testing, and potential applications of three forms of miniaturized analytical instrumentation. The first is an optical fiber instrument for monitoring pH and other cations in aqueous solutions. The instrument couples chemically selective indicators that have been immobilized at porous polymeric films with a hardware package that provides the excitation light source, required optical components, and detection and data processing hardware. The second is a new form of a piezoelectric mass sensor. The sensor was fabricated by the deposition of a thin (5.5 μm) film of piezoelectric aluminum nitride (AlN). The completed deposition process yields a thin film resonator (TFR) that is shaped as a 400 μm square and supports a standing bulk acoustic wave in a longitudinal mode at frequencies of ∼1 GHz.

Life support systems for manned exploration missions are becoming increasingly complex. In next-generation manned space exploration, closed-loop control of all life support systems must be established, particularly for missions requiring extended human occupation of space or the lunar or martian surface. To accomplish this control, sensors must be developed that are capable of monitoring and feeding back information on the concentrations of a number of chemical and biochemical substances. Two critical sets of variables that must be monitored are: oxygen concentration and flow in crew air supply (both in capsules and in suits and masks); carbon dioxide, oxygen, and moisture content in hydroponic or other food- and oxygen-producing life support systems.

Aircraft modifications have been developed to make F/A-18D Hornets capable of being converted to a reconnaissance configuration which includes both optical and infrared sensors. A major design challenge was to prevent fog formation on the two exterior moldline windows used for viewing by these sensors. Antifogging was required during a rapid 7620 m/min (25,000 ft/min) descent into humid atmospheric conditions following a sustained cold soak at altitude. This paper describes the design development and laboratory verification testing of the two unique antifog systems selected to meet this requirement.

We have developed two modules for use in computer-aided design (CAD) of crewstation environments that enhance the designer's appreciation of factors influencing the pilot's vision and visual processing capacity. The Binocular Optics Module (BOM) is an interactive tool for visualizing geometric aspects of 1) how retinal imagery of the environment changes on the pilot's retinas under conditions of eye and object motion, and 2) how visual capabilities that can be modeled as regions or contours on the retinas, affect spatial perception of the environment. The Visual Performance Module (VPM) contains a signal processing model of human visual discrimination that quantitatively predicts visual discrimination performance. The outputs of the VPM are retinal contours that represent performance probabilities. These contours may be used as inputs to the BOM for visualizing those volumes of space within the crewstation that bound different levels of the pilot's of visual discrimination capability.

An experimental-and-analytical thermal control coatings (TCC) degradation process research methods based on flight test data has been discussed. The application of this method allows to set up a diagnostic experiment using spacecraft (SC) on-board systems, to identify radiation parameter values based on indirect information on transient temperature changes of the TCC test specimens, and to perform a long-term prediction of the TCC's integrated absorptance variations. An alternative approach to implement the strategies for increasing accuracy and information capacity of the test dates based of the inverse non-linear problem solution concept has proposed. Computation techniques and algorithms based on multidimensional random search and iterative reqularization methods have presented.

The MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) instrument is part of the payload of the European Space Agency's (ESA) earth observation satellite ENVISAT-1. The instrument analyses the electromagnetic radiation from the earth atmosphere in the spectral region of 4μ to 14μ wavelength. In this way vertical concentration profiles of trace gases in the atmosphere can be determined. The instrument consists of two subassemblies: the optics module and the electronics module. The optics module is a casing in which the optical imaging equipment and the signal detectors are located. The electronics module houses the control units for the instrument and consists of several boxes mounted on the S/C in the vicinity of the optics module, interconnected with harness. In a previous paper the thermal design of the instrument was explained. This paper will focus on the thermal design verification of the optics module.

Advanced environmental monitoring and control technologies are required for future human exploration of the solar system, where the spacecraft air supply must be recycled for continuous use over a period of months to years. Primary target compounds and 180-day Spacecraft Maximum Acceptable Concentration (SMAC's) limits have been identified for several classes of contaminants. For the identified major species, O2, CO, CO2 and CH4, room-temperature, near-IR tunable diode laser absorption sensors have already been demonstrated with ∼1 ppm-meter detection limits (at or below many of the current SMAC limits) and continuous response band widths on the order of 1 Hz. Additional sensitivity can be achieved using compact long pathlength multipass optical cells. These new generation diode laser sensors use communications-type diode lasers in compact, fiber-coupled packages ideal for remote and autonomous sensor applications.

Increasingly complex missions with reduced budgets has placed a premium on “better, cheaper, faster” system approaches for producing spacecraft. The natural consequence of this pressure to improve quality while reducing process time and expense is that activities once considered essential to design and development are now viewed as luxuries. To produce timely inputs during the condensed design phase, the spacecraft subsystem architect must continually improve the efficiency of analysis activities. This type of improvement is particularly necessary in the area of thermal analysis, which is often viewed as a peripheral activity. However, through the use of enhanced software analysis tools, the thermal engineer can ensure a comprehensive spacecraft thermal analysis that yields timely system design inputs in a cost-effective manner.

In the paper the we discuss how the thermal behavior of the Advanced X-ray Astrophysics Facility (AXAF) optical system has been modeled and tested, and how these efforts have influenced the design of the telescope, especially as it relates the imaging performance. This includes the passive/active system covering the space-facing aperture known as the thermal “precollimator”, the mechanical support system that allows the large optical elements to survive the rigors of test in one-G and launch yet minimally affecting on-orbit optical performance, and the active thermal control design of the telescope. Methodologies for the frequently difficult task of transferring results from thermal analysis software to mechanical finite-element analyzers to model thermal deformations are discussed. The complexity of these distortions of the surfaces of the mirror elements required the use of optical raytrace models to assess imaging performance of the telescope.

A microhygrometer has been developed at JPL's Microdevices Laboratory based on the principle of dewpoint/frostpoint detection. The surface acoustic wave device used in this instrument is approximately two orders of magnitude more sensitive to condensation than the optical sensor used in chilled-mirror hygrometers. In tests in the laboratory and on the NASA DC8, the SAW hygrometer has demonstrated more than an order of magnitude faster response than commercial chilled-mirror hygrometers, while showing comparable accuracy under steady-state conditions. Current development efforts are directed toward miniaturization and optimization of the microhygrometer electronics for flight validation experiments on a small radiosonde balloon.