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At least 109 records · Page 6
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NASA NTRS2000

Thin-Film Photovoltaic Solar Array Parametric Assessment

This paper summarizes a study that had the objective to develop a model and parametrically determine the circumstances for which lightweight thin-film photovoltaic solar arrays would be more beneficial, in terms of mass and cost, than arrays using high-efficiency crystalline solar cells. Previous studies considering arrays with near-term thin-film technology for Earth orbiting applications are briefly reviewed. The present study uses a parametric approach that evaluated the performance of lightweight thin-film arrays with cell efficiencies ranging from 5 to 20 percent. The model developed for this study is described in some detail. Similar mass and cost trends for each array option were found across eight missions of various power levels in locations ranging from Venus to Jupiter. The results for one specific mission, a main belt asteroid tour, indicate that only moderate thin-film cell efficiency (approx. 12 percent) is necessary to match the mass of arrays using crystalline cells with much greater efficiency (35 percent multi-junction GaAs based and 20 percent thin-silicon). Regarding cost, a 12 percent efficient thin-film array is projected to cost about half is much as a 4-junction GaAs array. While efficiency improvements beyond 12 percent did not significantly further improve the mass and cost benefits for thin-film arrays, higher efficiency will be needed to mitigate the spacecraft-level impacts associated with large deployed array areas. A low-temperature approach to depositing thin-film cells on lightweight, flexible plastic substrates is briefly described. The paper concludes with the observation that with the characteristics assumed for this study, ultra-lightweight arrays using efficient, thin-film cells on flexible substrates may become a leading alternative for a wide variety of space missions.

Hoffman, David J.↗
NASA NTRS2004

Large Format Arrays for Far Infrared and Millimeter Astronomy

Some of the most compelling questions in modem astronomy are best addressed with submillimeter and millimeter observations. The question of the role of inflation in the early evolution of the universe is best addressed with large sensitive arrays of millimeter polarimeters. The study of the first generations of galaxies requires sensitive submillimeter imaging, which can help us to understand the history of energy release and nucleosynthesis in the universe. Our ability to address these questions is dramatically increasing, driven by dramatic steps in the sensitivity and size of available detector arrays. While the MIPS instrument on the SIRTF mission will revolutionize far infrared astronomy with its 1024 element array of photoconductors, thermal detectors remain the dominant technology for submillimeter and millimeter imaging and polarimetry. The last decade has seen the deployment of increasingly large arrays of bolometers, ranging from the 48 element arrays deployed on the KAO in the late 198Os, to the SHARC and SCUBA arrays in the 1990s. The past years have seen the deployment of a new generation of larger detector arrays in SHARC II (384 channels) and Bolocam (144 channels). These detectors are in operation and are beginning to make significant impacts on the field. Arrays of sensitive submillimeter bolometers on the SPIRE instrument on Herschel will allow the first large areas surveys of the sky, providing important insight into the evolution of galaxies. The next generation of detectors, led by SCUBA II, will increase the focal scale of these instruments by an order of magnitude. Two major missions are being planned by NASA for which further development of long wavelength detectors is essential, The SAFlR mission, a 10-m class telescope with large arrays of background limited detectors, will extend our reach into the epoch of initial galaxy formation. A major goal of modem cosmology is to test the inflationary paradigm in the early evolution of the universe. To this end, a mission is planned to detect the imprint of inflation on the CMB by precision measurement of its polarization. This work requires very large arrays of sensitive detectors which can provide unprecedented control of a wide range of systematic errors, given the small amplitude of the signal of interest. We will describe the current state of large format detector arrays, the performance requirements set by the new missions, and the different approaches being developed in the community to meet these requirements. We are confident that within a decade, these developments will lead to dramatic advances in our understanding of the evolution of the universe.

Moseley, Harvey↗
NASA NTRS1999

Effect of Directional Array Size on the Measurement of Airframe Noise Components

A study was conducted to examine the effects of overall size of directional (or phased) arrays on the measurement of aeroacoustic components. An airframe model was mounted in the potential core of an open-jet windtunnel, with the directional arrays located outside the flow in an anechoic environment. Two array systems were used; one with a solid measurement angle that encompasses 31.6 deg.of source directivity and a smaller one that encompasses 7.2 deg. The arrays, and sub-arrays of various sizes, measured noise from a calibrator source and flap edge model setups. In these cases, noise was emitted from relatively small, but finite size source regions, with intense levels compared to other sources. Although the larger arrays revealed much more source region detail, the measured source levels were substantially reduced due to finer resolution compared to that of the smaller arrays. To better understand the measurements quantitatively, an analytical model was used to define the basic relationships between array to source region sizes and measured output level. Also, the effect of noise scattering by shear layer turbulence was examined using the present data and those of previous studies. Taken together, the two effects were sufficient to explain spectral level differences between arrays of different sizes. An important result of this study is that total (integrated) noise source levels are retrievable and the levels are independent of the array size as long as certain experimental and processing criteria are met. The criteria for both open and closed tunnels are discussed. The success of special purpose diagonal-removal processing in obtaining integrated results is apparently dependent in part on source distribution. Also discussed is the fact that extended sources are subject to substantial measurement error, especially for large arrays.

Brooks, Thomas F.↗
NASA NTRS2004

Ka-Band Multibeam Aperture Phased Array Being Developed

Phased-array antenna systems offer many advantages to low-Earth-orbiting satellite systems. Their large scan angles and multibeam capabilities allow for vibration-free, rapid beam scanning and graceful degradation operation for high rate downlink of data to users on the ground. Technology advancements continue to reduce the power, weight, and cost of these systems to make phased arrays a competitive alternative in comparison to the gimbled reflector system commonly used in science missions. One effort to reduce the cost of phased arrays is the development of a Ka-band multibeam aperture (MBA) phased array by Boeing Corporation under a contract jointly by the NASA Glenn Research Center and the Office of Naval Research. The objective is to develop and demonstrate a space-qualifiable dual-beam Ka-band (26.5-GHz) phased-array antenna. The goals are to advance the state of the art in Ka-band active phased-array antennas and to develop and demonstrate multibeam transmission technology compatible with spacecraft in low Earth orbit to reduce the cost of future missions by retiring certain development risks. The frequency chosen is suitable for space-to-space and space-to-ground communication links. The phased-array antenna has a radiation pattern designed by combining a set of individual radiating elements, optimized with the type of radiating elements used, their positions in space, and the amplitude and phase of the currents feeding the elements. This arrangement produces a directional radiation pattern that is proportional to the number of individual radiating elements. The arrays of interest here can scan the main beam electronically with a computerized algorithm. The antenna is constructed using electronic components with no mechanical parts, and the steering is performed electronically, without any resulting vibration. The speed of the scanning is limited primarily by the control electronics. The radiation performance degrades gracefully if a portion of the elements fail. The arrays can be constructed to conform to a mounting surface, and multibeam capability is integral to the design. However, there are challenges for mission designers using monolithic-microwave-integrated-circuit- (MMIC-) based arrays because of reduced power efficiency, higher costs, and certain system effects that result in link degradations. The multibeam aperture phased-array antenna development is attempting to address some of these issues, particularly manufacturing, costs, and system performance.

Reinhart, Richard C.↗
NASA NTRS2008

Contrast Measurements of the Microshutter Arrays for the NIRspec

We have been developing programmable microshutter arrays for the Near Infrared Spectrometer (NIRSpec) on the James Webb Space telescope (JWST). These arrays are an enabling technology that allows to turn NIRSpec into a powerful multi-object spectrometer and tremendously increase its efficiency. The arrays are essentially 2D programmable masks that are designed to operate at cryogenic temperatures of JWST. The primary optical characteristic of the microshutter array is a contrast, that is defined as a ratio of the transmitted light intensity through open shutters to the intensity of the transmitted light through the closed shutters. To eliminate the noise and confusion from other sources in the field of view and therefore to improve the detection limit, the contrast provided by the microshutter array should be very high, with the goal of 10,000. The test system that we have developed specifically for the purpose of the high contrast characterization of the microshutter array devices has been used to test several microshutter arrays. It is capable of measuring contrast values of up to 10^5 and therefore can reliably measure contrast values of the arrays that satisfy the requirements. The arrays have been characterized for the contrast ratio and its behavior with temperature and other array operating parameters. The arrays that we have tested meet or exceed the NiRSpec requirements.

Kutyrev, Alexander↗
NASA NTRS2006

NASA Solar Array Demonstrates Commercial Potential

A state-of-the-art solar-panel array demonstration site at NASA's Dryden Flight Research Center provides a unique opportunity for studying the latest in high-efficiency solar photovoltaic cells. This five-kilowatt solar-array site (see Figure 1) is a technology-transfer and commercialization success for NASA. Among the solar cells at this site are cells of a type that was developed in Dryden Flight Research Center s Environmental Research Aircraft and Sensor Technology (ERAST) program for use in NASA s Helios solar-powered airplane. This cell type, now denoted as A-300, has since been transferred to SunPower Corporation of Sunnyvale, California, enabling mass production of the cells for the commercial market. High efficiency separates these advanced cells from typical previously commercially available solar cells: Whereas typical previously commercially available cells are 12 to 15 percent efficient at converting sunlight to electricity, these advanced cells exhibit efficiencies approaching 23 percent. The increase in efficiency is due largely to the routing of electrical connections behind the cells (see Figure 2). This approach to increasing efficiency originated as a solution to the problem of maximizing the degree of utilization of the limited space available atop the wing of the Helios airplane. In retrospect, the solar cells in use at this site could be used on Helios, but the best cells otherwise commercially available could not be so used, because of their lower efficiencies. Historically, solar cells have been fabricated by use of methods that are common in the semiconductor industry. One of these methods includes the use of photolithography to define the rear electrical-contact features - diffusions, contact openings, and fingers. SunPower uses these methods to produce the advanced cells. To reduce fabrication costs, SunPower continues to explore new methods to define the rear electrical-contact features. The equipment at the demonstration site includes two fixed-angle solar arrays and one single-axis Sun-tracking array. One of the fixed arrays contains typical less-efficient commercial solar cells and is being used as a baseline for comparison of the other fixed array, which contains the advanced cells. The Sun-tracking array tilts to follow the Sun, using an advanced, real-time tracking device rather than customary pre-programmed mechanisms. Part of the purpose served by the demonstration is to enable determination of any potential advantage of a tracking array over a fixed array. The arrays are monitored remotely on a computer that displays pertinent information regarding the functioning of the arrays.

Creech, Gray↗
NASA NTRS2011

Coupling Between Waveguide-Fed Slot Arrays

Coupling between two waveguide-fed planar slot arrays has been investigated using full-wave analysis. The analysis employs the method-of-moments solution to the pertinent coupled integral equations for the aperture electric field of all slots. In order to compute coupling between two arrays, the input port of the first array is excited with a TE(sub 10) mode wave while the second one is match-terminated. After solving the moment method matrix equations, the aperture fields of all slots are obtained and thereby the TE(sub 10) mode wave received at the input port of the second array is determined. Coupling between two arrays is the ratio of the wave amplitude arriving in the second array port to the incident wave amplitude at the first array port. The coupling mechanism has been studied as a function of spacing between arrays in different directions, e.g. the electric field plane, the magnetic field plane, and the diagonal plane. Computed coupling values are presented for different array geometries. This work is novel since it provides a good understanding of coupling between waveguide-fed slot arrays as a function of spacing and orientation for different aperture distributions and array architectures. This serves as a useful tool for antenna design engineers and system engineers.

Rengarajan, Sembiam↗
NASA NTRSDate not supplied

Government Reference Concept for a 10 kW Lunar South Pole Solar Array

Deployable and relocatable free-standing, solar arrays will be required for future lunar South Pole missions. Major design requirements for these arrays will be low mass, compact launch stowage, and highly reliable deployment and retraction performance. A novel conceptual design referred to as the Relocatable Solar Array (RSA) is presented fora 10 kW solar array to address these requirements. Simply stated, the concept is a pair of solar cell blankets freely hanging from a horizontal cross arm that is supported by a vertical slender telescoping mast, all of which, rests on a deployable tripod base. A major factor in simplifying this array is that the force exerted by lunar gravity is used to deploy and maintain the extension of the hanging array blankets. The other major factor in achieving the desired low mass and high volumetric efficiency is that the resulting array system operates in the vacuum, low-gravity, lunar environment with no deployed vibration frequency requirement. Such an environment enables the use of extraordinarily slender and low mass structural members to support the hanging array blankets. This concept was developed, in part, to serve as a NASA reference solar array concept against which other proposed arrays can be compared.

Space solar arrays, solar array structures, lunar ↗
NASA NTRS2021

Relocatable 10 kW Solar Array for Lunar South Pole Missions

Deployable, relocatable, free-standing solar arrays are being developed to provide modular power for future lunar South Pole missions. Major design requirements for these arrays will be low mass, compact launch stowage, and highly reliable deployment and retraction. This paper presents a novel conceptual design for a10 kW solar array to address these requirements referred to as the Relocatable Solar Array (RSA).Simply stated, the concept is a pair of solar cell blankets freely hanging from a horizontal cross arm supported by a vertical, slender, telescoping mast resting on a deployable tripod base. A major factor in simplifying the design is that the force exerted by lunar gravity is used to deploy and maintain extension of the hanging array blankets. A second major factor in achieving the desired low mass and high volumetric efficiency is that the array operates in the vacuum, low-gravity, lunar environment with no deployed vibration frequency requirement. Such a low-load environment enables use of extraordinarily slender and low mass structural members to support the hanging array blankets. This concept was developed, in part, to serve as a NASA reference solar array concept against which other proposed arrays can be compared.

Lunar Surface Power↗
NASA NTRS1978

Feasibility Study of Solar Dome Encapsulation of Photovoltaic Arrays

The technical and economic advantages of using air-supported plastic enclosures to protect flat plate photovoltaic arrays are described. Conceptual designs for a fixed, latitude-tilt array and a fully tracking array were defined. Detailed wind loads and strength analyses were performed for the fixed array. Detailed thermal and power output analyses provided array performance for typical seasonal and extreme temperature conditions. Costs of each design as used in a 200 MWe central power station were defined from manufacturing and material cost estimates. The capital cost and cost of energy for the enclosed fixed-tilt array were lower than for the enclosed tracking array. The enclosed fixed-tilt array capital investment was 38% less, and the levelized bus bar energy cost was 26% less than costs for a conventional, glass-encapsulated array design. The predicted energy cost for the enclosed fixed array was 79 mills/kW-h for direct current delivered to the power conditioning units.

Source record↗
NASA NTRS1979

Wind Loads on Flat Plate Photovoltaic Array Fields

The aerodynamic forces resulting from winds acting on flat plate photovoltaic arrays were investigated. Local pressure distributions and total aerodynamic forces on the arrays are shown. Design loads are presented to cover the conditions of array angles relative to the ground from 20 deg to 60 deg, variable array spacings, a ground clearance gap up to 1.2 m (4 ft) and array slant heights of 2.4 m (8 ft) and 4.8 m (16 ft). Several means of alleviating the wind loads on the arrays are detailed. The expected reduction of the steady state wind velocity with the use of fences as a load alleviation device are indicated to be in excess of a factor of three for some conditions. This yields steady state wind load reductions as much as a factor of ten compared to the load incurred if no fence is used to protect the arrays. This steady state wind load reduction is offset by the increase in turbulence due to the fence but still an overall load reduction of 2.5 can be realized. Other load alleviation devices suggested are the installation of air gaps in the arrays, blocking the flow under the arrays and rounding the edges of the array. A wind tunnel test plan to supplement the theoretical study and to evaluate the load alleviation devices is outlined.

Miller, R.↗
NASA NTRS1994

The 20 GHz circularly polarized, high temperature superconducting microstrip antenna array

The primary goal was to design and characterize a four-element, 20 GHz, circularly polarized microstrip patch antenna fabricated from YBa2Cu3O(x) superconductor. The purpose is to support a high temperature superconductivity flight communications experiment between the space shuttle orbiter and the ACTS satellite. This study is intended to provide information into the design, construction, and feasibility of a circularly polarized superconducting 20 GHz downlink or cross-link antenna. We have demonstrated that significant gain improvements can be realized by using superconducting materials for large corporate fed array antennas. In addition, we have shown that when constructed from superconducting materials, the efficiency, and therefore the gain, of microstrip patches increases if the substrate is not so thick that the dominant loss mechanism for the patch is radiation into the surface waves of the conductor-backed substrate. We have considered two design configurations for a superconducting 20 GHz four-element circularly polarized microstrip antenna array. The first is the Huang array that uses properly oriented and phased linearly polarized microstrip patch elements to realize a circularly polarized pattern. The second is a gap-coupled array of circularly polarized elements. In this study we determined that although the Huang array operates well on low dielectric constant substrates, its performance becomes extremely sensitive to mismatches, interelement coupling, and design imperfections for substrates with high dielectric constants. For the gap-coupled microstrip array, we were able to fabricate and test circularly polarized elements and four-element arrays on LaAlO3 using sputtered copper films. These antennas were found to perform well, with relatively good circular polarization. In addition, we realized a four-element YBa2Cu3O(x) array of the same design and measured its pattern and gain relative to a room temperature copper array. The patterns were essentially the same as that for the copper array. The measured gain of the YBCO antenna was greater than that for the room temperature copper design at temperatures below 82K, reaching a value of 3.4 dB at the lowest temperatures.

Morrow, Jarrett D.↗
NASA NTRS1994

High-performance, flexible, deployable array development for space applications

Flexible, deployable arrays are an attractive alternative to conventional solar arrays for near-term and future space power applications, particularly due to their potential for high specific power and low storage volume. Combined with low-cost flexible thin-film photovoltaics, these arrays have the potential to become an enabling or an enhancing technology for many missions. In order to expedite the acceptance of thin-film photovoltaics for space applications, however, parallel development of flexible photovoltaics and the corresponding deployable structure is essential. Many innovative technologies must be incorporated in these arrays to ensure a significant performance increase over conventional technologies. For example, innovative mechanisms which employ shape memory alloys for storage latches, deployment mechanisms, and array positioning gimbals can be incorporated into flexible array design with significant improvement in the areas of cost, weight, and reliability. This paper discusses recent activities at Martin Marietta regarding the development of flexible, deployable solar array technology. Particular emphasis is placed on the novel use of shape memory alloys for lightweight deployment elements to improve the overall specific power of the array. Array performance projections with flexible thin-film copper-indium-diselenide (CIS) are presented, and government-sponsored solar array programs recently initiated at Martin Marietta through NASA and Air Force Phillips Laboratory are discussed.

Gehling, Russell N.↗
NASA NTRS1995

Planetary and deep space requirements for photovoltaic solar arrays

In the past 25 years, the majority of interplanetary spacecraft have been powered by nuclear sources. However, as the emphasis on smaller, low cost missions gains momentum, the majority of missions now being planned will use photovoltaic solar arrays. This will present challenges to the solar array builders, inasmuch as planetary requirements usually differ from earth orbital requirements. In addition, these requirements often differ greatly, depending on the specific mission; for example, inner planets vs. outer planets, orbiters vs. flybys, spacecraft vs. landers, and so on. Also, the likelihood of electric propulsion missions will influence the requirements placed on solar array developers. The paper will discuss representative requirements for a range of planetary missions now in the planning stages. Insofar as inner planets are concerned, a Mercury orbiter is being studied with many special requirements. Solar arrays would be exposed to high temperatures and a potentially high radiation environment, and will need to be increasingly pointed off sun as the vehicle approaches Mercury. Identification and development of cell materials and arrays at high incidence angles will be critical to the design. Missions to the outer solar system that have been studied include a Galilean orbiter and a flight to the Kuiper belt. While onboard power requirements would be small (as low as 10 watts), the solar intensity will require relatively large array areas. As a result, such missions will demand extremely compact packaging and low mass structures to conform to launch vehicle constraints. In turn, the large are, low mass designs will impact allowable spacecraft loads. Inflatable array structures, with and without concentration, and multiband gap cells will be considered if available. In general, the highest efficiency cell technologies operable under low intensity, low temperature conditions are needed. Solar arrays will power missions requiring as little as approximately 100 watts, up to several kilowatts (at Earth) in the case of solar electric propulsion missions. Thus, mass and stowage volume minimization will be required over a range of array sizes. Concentrator designs, inflatable structures, and the combination of solar arrays with the telecommunications system have been proposed. Performance, launch vehicle constraints, an cost will be the principal parameters in the design trade space. Other special applications will also be discussed, including requirements relating to planetary landers and probes. In those cases, issues relating to shock loads on landing, operability in (possibly dusty) atmospheres, and extreme temperature cycles must be considered, in addition to performance, stowed volume, and costs.

Bankston, C. P.↗
NASA NTRS1995

Ka-band MMIC array system for ACTS aeronautical terminal experiment (Aero-X)

During the summer of 1994, the Advanced Communication Technology Satellite (ACTS) Aeronautical Terminal Experiment (Aero-X) was successfully completed by the NASA Lewis Research Center (LeRC) and the Jet Propulsion Laboratory (JPL). 4.8 and 9.6 Kbps duplex voice links were established between the LeRC Learjet and the ACTS Link Evaluation Terminal (LET) in Cleveland, Ohio, via the ACTS. The antenna system used in this demonstration was developed by LeRC and featured LeRC and US Air Force experimental arrays using GaAs MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The antenna system consisted of three arrays mounted inside the LeRC Learjet, pointing out through the windows. An open loop tracking controller developed by LeRC used information from the aircraft position and attitude sensors to automatically steer the arrays toward ACTS during flight JPL ACTS Mobile Terminal (AMT) system hardware was used as transceivers both on the aircraft and at the LET. The single 32 element MMIC transmit array developed by NASA/LeRC and Texas Instruments has an EIRP of 23.4 dBW at boresight. The two 20 GHz MMIC receive arrays were developed in a cooperative effort with the USAF Rome Laboratory/Electronic System Center, taking advantage of existing USAF array development contracts with Boeing and Martin Marietta. The Boeing array has 23 elements and a G/T of 16/6 db/degK at boresight. The Martin Marietta array has 16 elements and a G/T of 16.1 db/degK at boresight. The three proof-of-concept arrays, the array control system and their integration and operation in the Learjet for Aero-X are described.

Raquet, Charles A.↗
NASA NTRS1997

The Effects of Linear Microphone Array Changes on Computed Sound Exposure Level Footprints

Airport land planning commissions often are faced with determining how much area around an airport is affected by the sound exposure levels (SELS) associated with helicopter operations. This paper presents a study of the effects changing the size and composition of a microphone array has on the computed SEL contour (ground footprint) areas used by such commissions. Descent flight acoustic data measured by a fifteen microphone array were reprocessed for five different combinations of microphones within this array. This resulted in data for six different arrays for which SEL contours were computed. The fifteen microphone array was defined as the 'baseline' array since it contained the greatest amount of data. The computations used a newly developed technique, the Acoustic Re-propagation Technique (ART), which uses parts of the NASA noise prediction program ROTONET. After the areas of the SEL contours were calculated the differences between the areas were determined. The area differences for the six arrays are presented that show a five and a three microphone array (with spacing typical of that required by the FAA FAR Part 36 noise certification procedure) compare well with the fifteen microphone array. All data were obtained from a database resulting from a joint project conducted by NASA and U.S. Army researchers at Langley and Ames Research Centers. A brief description of the joint project test design, microphone array set-up, and data reduction methodology associated with the database are discussed.

Mueller, Arnold W.↗
NASA NTRS1998

Design and Use of Microphone Directional Arrays for Aeroacoustic Measurements

An overview of the development of two microphone directional arrays for aeroacoustic testing is presented. These arrays were specifically developed to measure airframe noise in the NASA Langley Quiet Flow Facility. A large aperture directional array using 35 flush-mounted microphones was constructed to obtain high resolution noise localization maps around airframe models. This array possesses a maximum diagonal aperture size of 34 inches. A unique logarithmic spiral layout design was chosen for the targeted frequency range of 2-30 kHz. Complementing the large array is a small aperture directional array, constructed to obtain spectra and directivity information from regions on the model. This array, possessing 33 microphones with a maximum diagonal aperture size of 7.76 inches, is easily moved about the model in elevation and azimuth. Custom microphone shading algorithms have been developed to provide a frequency- and position-invariant sensing area from 10-40 kHz with an overall targeted frequency range for the array of 5-60 kHz. Both arrays are employed in acoustic measurements of a 6 percent of full scale airframe model consisting of a main element NACA 632-215 wing section with a 30 percent chord half-span flap. Representative data obtained from these measurements is presented, along with details of the array calibration and data post-processing procedures.

Humphreys, William M., Jr.↗
NASA NTRS2000

The DS1 Mission and the Validation of the SCARLET Advanced Array

On October 24, 1998, the first of the NASA New Millenium Spacecraft, DS1, was successfully launched into Space. The objectives for this spacecraft are to test advanced technologies that can reduce the cost or risk of future missions. One of these technologies is the SCARLET concentrating solar array. Although part of the advanced technology validation study, the array is also the spacecraft's power source. Funded by BMDO, the SCARLET concentrator solar array is the first application of a refractive lens concentrator designed for space applications. As part of the DS1 validation process, the amount of diagnostics data that will be acquired is more extensive than would be the norm for a more conventional solar array. These data include temperature measurements at numerous locations on the 2-wing, 4-panel per wing, solar array. For each panel, one 5-cell module in one of the circuit strings is wired so that a complete I-V curve can be obtained. This data is used to verify sun pointing accuracy and array output performance. In addition, the spacecraft power load can be varied in a number of discrete steps from a small fraction of the array total power capability, up to maximum power. For each of the power loads, array operating voltage can be measured along with the current output from each wing. Preliminary in-space measurements suggest SCARLET performance is within one (1) percent of predictions made from ground data. This paper will briefly discuss the SCARLET configuration and critical features. Emphasis will be given to the results of the in-space validation, including array performance as a function of changing solar distance and array performance compared to pre-launch predictions.

Stella, Paul M.↗