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NASA NTRS1989

Laboratory characterization of direct readout Si:Sb and Si:Ga infrared detector arrays

Highlights of recent results obtained at Ames Research Center in performance evaluations of infrared detector arrays are presented. Antimony- and gallium-doped silicon direct readout 58x62 element hybrid devices from Ames' ongoing detector technology development program are described. The observed characteristics meet most of the performance goals specified by the Space Infrared Telescope Facility (SIRTF) instrument teams and compare favorably with the best performance reported for discrete non-integrating extrinsic silicon detectors. Initial results of radiation environment testing are reported, and non-ideal behavior demonstrated by these test devices is discussed.

Mckelvey, Mark E.↗

NASA NTRS1990

Starburst outflows from nearby galaxies

Starburst outflows from NGC 5461, 1569 and M82 are discussed. The Sc I galaxy, M101, is reknowned for the kpc-size superassociations of star clusters and HII regions that dominate its spiral arms. NGC 5461 is one of the brightest of these superassociations, rivaling the Large Magellanic Cloud in H alpha luminosity. The NGC 5461 superassociation is dominated by a single unresolved HII region of outstanding luminosity (approx. 1000 Orion nebulae). Detailed examination of corresponding continuum images indicates that only the southern plume has any sort of stellar counterpart. The other plumes are clearly diffuse with no underlying hot stars. An image of NGC 1569 is discussed. Besides showing the peculiar arm noted by Zwicky (1971) and the filamentary extensions to the North and South (as noted by Hodge 1974), this image also reveals two arc-like features of diffuse ionized gas to the South. Both arcs are concentric with the bright center of the galaxy - where the super star clusters, A and B are located. The inner arc (Arc 1) appears to follow the same curve as the SW arm thus suggesting that the two features represent limb-brightened fragments of vast superbubble that was blown out by a central starburst sometime in the past. As the classic starburst galaxy, M82 displays all the luminous hallmarks of intense high-mass star formation and outflow activity. The diffuse H alpha and x ray emitting gas along the minor axis provides especially good evidence for a bipolar outflow of hot gas which is shock heating the swept-up interstellar medium (ISM) to temperatures of approx. 10(exp 4) K. An image shows the H alpha emission within the disk and along the minor axis. Another image shows the same field in the light of near-infrared. Both figures are based on charge coupled device images taken with the McGraw-Hill 1.3 m telescope (Waller 1989). The longer wavelength emission clearly shows a more extended morphology along the major axis. The morphological discrepancy is most likely due to the greater obscuration by dust suffered by the H alpha photons. A third image shows the map of visual extinction that researchers derive from a pixel-by-pixel comparison of the (SIII) and H alpha fluxes. The greatest extinctions are evident along an arc that includes two especially obscured regions on opposite sides of the bursting nucleus.

Waller, William H.↗

NASA NTRS1994

A NASA/Industry/University Partnership for Development of Dual-Use Vibration Isolation Technology

A partnership is described that was formed as a result of a NASA university grant for the study of wire rope vibration isolation systems. Vibration isolators of this type are currently used in the Space Shuttle Orbiter and engine test facility, and have potential application in the international space station and other space vehicles. Wire rope isolators were considered for use on the Hubble Space Telescope and the military has used wire rope technology extensively. The desire of the wire rope industry to expand sales in commercial markets coupled with results of the prior NASA funded study, led to the formation of a partnership including NASA, the university involved in the research grant, and a small company that designs wire rope systems. Goals include the development of improved mathematical models and a designers handbook to facilitate the use of the new modeling tools.

Tinker, Michael L.↗

NASA NTRS1996

The Michelson Stellar Interferometer Error Budget for Triple Triple-Satellite Configuration

This report presents the results of a study of the instrumentation tolerances for a conventional style Michelson stellar interferometer (MSI). The method used to determine the tolerances was to determine the change, due to the instrument errors, in the measured fringe visibility and phase relative to the ideal values. The ideal values are those values of fringe visibility and phase that would be measured by a perfect MSI and are attributable solely to the object being detected. Once the functional relationship for changes in visibility and phase as a function of various instrument errors is understood it is then possible to set limits on the instrument errors in order to ensure that the measured visibility and phase are different from the ideal values by no more than some specified amount. This was done as part of this study. The limits we obtained are based on a visibility error of no more than 1% and a phase error of no more than 0.063 radians (this comes from 1% of 2(pi) radians). The choice of these 1% limits is supported in the literture. The approach employed in the study involved the use of ASAP (Advanced System Analysis Program) software provided by Breault Research Organization, Inc., in conjunction with parallel analytical calculations. The interferometer accepts object radiation into two separate arms each consisting of an outer mirror, an inner mirror, a delay line (made up of two moveable mirrors and two static mirrors), and a 10:1 afocal reduction telescope. The radiation coming out of both arms is incident on a slit plane which is opaque with two openings (slits). One of the two slits is centered directly under one of the two arms of the interferometer and the other slit is centered directly under the other arm. The slit plane is followed immediately by an ideal combining lens which images the radiation in the fringe plane (also referred to subsequently as the detector plane).

Marathay, Arvind S.↗

NASA NTRS1997

Exotic Molecules in Space: A Coordinated Astronomical, Laboratory, and Theoretical Study

The past year has been a period of spectacular progress in our investigation of exotic molecules of astrophysical interest. During this period an entirely new spectrometer for the investigation of reactive molecules was finished: a Fourier-transform microwave spectrometer with a supersonic molecular beam. The instrument is operating almost flawlessly, and during the above period of less than two years has discovered the 23 new carbon chain and ring-chain molecules. Seventeen research papers, nearly all in leading refereed journals such as the Astrophysical Journal and the Journal of Chemical Physics have been published. At least five more papers are being prepared for publication. Already four of our new molecules have been detected in space with large radio telescopes. In many ways the most interesting of these is HC(11)N, which now ranks as the largest molecule definitely identified beyond the solar system. Nearly all the other new molecules are candidates for astronomical detection, and we will be disappointed if a number of them are not found as more sensitive receivers and larger telescopes are constructed. During the next year we expect this wave of discovery to continue, and to insure rapid progress we have designed an even more sensitive spectrometer which will operate at the temperature of liquid helium. The goal of this system is to enhance the sensitivity of Fourier-transform spectroscopy by a further factor of 20 to 50, achieving this by reducing the amplifier and thermal noise to levels routinely achieved in radio astronomy. This new instrument offers a number of technical challenges in cryogenic and microwave engineering, but none of these appears to be insurmountable, and our current schedule is to have the helium cooled system operating within the next six months. A number of investigations continued with our conventional free space spectrometer, which remains a powerful complement to our new FTM instrument.

Thaddeus, Patrick↗

NASA NTRS1998

Advanced Detector and Waveform Digitizer for Water Vapor DIAL Systems

Measurement of atmospheric water vapor has become a major requirement for understanding moist-air processes. Differential absorption lidar (DIAL) is a technique best suited for the measurement of atmospheric water vapor. NASA Langley Research Center is continually developing improved DIAL systems. One aspect of current development is focused on the enhancement of a DIAL receiver by applying state-of-the-art technology in building a new compact detection system that will be placed directly on the DIAL receiver telescope. The newly developed detection system has the capability of being digitally interfaced with a simple personal computer, using a discrete input/output interface. This has the potential of transmitting digital data over relatively long distances instead of analog signals, which greatly reduces measurement noise. In this paper, we discuss some results from the new compact water vapor DIAL detection system which includes a silicon based avalanche photodiode (APD) detector, a 14-bit, 10-MHz waveform digitizer, a microcontroller and other auxiliary electronics. All of which are contained on a small printed-circuit-board. This will significantly reduce the weight and volume over the current CAMAC system and eventually will be used in a water vapor DIAL system on an unpiloted atmospheric vehicle (UAV) aircraft, or alternatively on an orbiting spacecraft.

Refaat, Tamer F.↗

NASA NTRS2003

Space Studies Board Annual Report, 2003

The Space Studies Board is a unit of the NRC's Division on Engineering and Physical Sciences (DEPS), and it reports to the Division for oversight. DEPS is one of six major program units of the NRC through which the institution conducts its operations on behalf of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. Within DEPS there are a total of 14 boards that cover a broad range of physical science and engineering disciplines and mission areas. Members of the DEPS Committee on Engineering and Physical Sciences provide advice on Board membership and advise on proposed new projects to be undertaken by the Board or its committees. Every 3 years the DEPS Committee also reviews the overall operations of each of its boards. The last review of the SSB was in 2001. The Board meets three times per year to review the activities of its committees and task groups and to be briefed on and discuss major space policy issues. An internal executive committee composed of seven at-large members of the Board meets at least once a year and may convene via conference call at other times to plan for SSB activities and to advise the chair between meetings. All projects proposed to be conducted by standing committees or ad hoctask groups must first be reviewed and approved by the Board or its executive committee, and the Board monitors the progress of the projects throughout the course of the studies.

National Aeronautics and Space Administration(NASA↗

NASA NTRS2014

NASA's Physics of the Cosmos and Cosmic Origins Technology Development Programs

NASA's Physics of the Cosmos (PCOS) and Cosmic Origins (COR) Program Offices, established in 2011, reside at the NASA Goddard Space Flight Center (GSFC). The offices serve as the implementation arm for the Astrophysics Division at NASA Headquarters. We present an overview of the programs' technology development activities and technology investment portfolio, funded by NASA's Strategic Astrophysics Technology (SAT) program. We currently fund 19 technology advancements to enable future PCOS and COR missions to help answer the questions "How did our universe begin and evolve?" and "How did galaxies, stars, and planets come to be?" We discuss the process for addressing community-provided technology gaps and Technology Management Board (TMB)-vetted prioritization and investment recommendations that inform the SAT program. The process improves the transparency and relevance of our technology investments, provides the community a voice in the process, and promotes targeted external technology investments by defining needs and identifying customers. The programs' goal is to promote and support technology development needed to enable missions envisioned by the National Research Council's (NRC) "New Worlds, New Horizons in Astronomy and Astrophysics" (NWNH) Decadal Survey report [1] and the Astrophysics Implementation Plan (AIP) [2]. These include technology development for dark energy, gravitational waves, X-ray and inflation probe science, and a 4m-class UV/optical telescope to conduct imaging and spectroscopy studies, as a post-Hubble observatory with significantly improved sensitivity and capability.

Technology Management Board (TMB)↗

NASA NTRS2010

Airborne and Ground-Based Measurements Using a High-Performance Raman Lidar

A high-performance Raman lidar operating in the UV portion of the spectrum has been used to acquire, for the first time using a single lidar, simultaneous airborne profiles of the water vapor mixing ratio, aerosol backscatter, aerosol extinction, aerosol depolarization and research mode measurements of cloud liquid water, cloud droplet radius, and number density. The Raman Airborne Spectroscopic Lidar (RASL) system was installed in a Beechcraft King Air B200 aircraft and was flown over the mid-Atlantic United States during July August 2007 at altitudes ranging between 5 and 8 km. During these flights, despite suboptimal laser performance and subaperture use of the telescope, all RASL measurement expectations were met, except that of aerosol extinction. Following the Water Vapor Validation Experiment Satellite/Sondes (WAVES_2007) field campaign in the summer of 2007, RASL was installed in a mobile trailer for groundbased use during the Measurements of Humidity and Validation Experiment (MOHAVE-II) field campaign held during October 2007 at the Jet Propulsion Laboratory s Table Mountain Facility in southern California. This ground-based configuration of the lidar hardware is called Atmospheric Lidar for Validation, Interagency Collaboration and Education (ALVICE). During theMOHAVE-II field campaign, during which only nighttime measurements were made, ALVICE demonstrated significant sensitivity to lower-stratospheric water vapor. Numerical simulation and comparisons with a cryogenic frost-point hygrometer are used to demonstrate that a system with the performance characteristics of RASL ALVICE should indeed be able to quantify water vapor well into the lower stratosphere with extended averaging from an elevated location like Table Mountain. The same design considerations that optimize Raman lidar for airborne use on a small research aircraft are, therefore, shown to yield significant dividends in the quantification of lower-stratospheric water vapor. The MOHAVE-II measurements, along with numerical simulation, were used to determine that the likely reason for the suboptimal airborne aerosol extinction performance during theWAVES_2007 campaign was amisaligned interference filter. With full laser power and a properly tuned interference filter,RASL is shown to be capable ofmeasuring themain water vapor and aerosol parameters with temporal resolutions of between 2 and 45 s and spatial resolutions ranging from 30 to 330 m from a flight altitude of 8 km with precision of generally less than 10%, providing performance that is competitive with some airborne Differential Absorption Lidar (DIAL) water vapor and High Spectral Resolution Lidar (HSRL) aerosol instruments. The use of diode-pumped laser technology would improve the performance of an airborne Raman lidar and permit additional instrumentation to be carried on board a small research aircraft. The combined airborne and ground-based measurements presented here demonstrate a level of versatility in Raman lidar that may be impossible to duplicate with any other single lidar technique.

Whiteman, David N.↗

NASA NTRS1986

Instrumentation for optical remote sensing from space; Proceedings of the Meeting, Cannes, France, November 27-29, 1985

Papers are presented on such topics as the development of the Imaging Spectrometer for Shuttle and space platform applications; the in-flight calibration of pushbroom remote sensing instruments for the SPOT program; buttable detector arrays for 1.55-1.7 micron imaging; the design of the Improved Stratospheric and Mesospheric Sounder on the Upper Atmosphere Research Satellite; and SAGE II design and in-orbit performance. Consideration is also given to the Shuttle Imaging Radar-B/C instruments; the Venus Radar Mapper multimode radar system design; various ISO instruments (ISOCAM, ISOPHOT, and SWS and LWS); and instrumentation for the Space Infrared Telescope Facility.

Seeley, John S.↗

NASA NTRS2019

Persistent Assets in Zero-G and on Planetary Surfaces: Enabled by Modular Technology and Robotic Operations

Space operations are on the cusp of a revolutionary new operational paradigm that leverages modular systems and recurring robotic visits to “Persistent Assets” enabling asset maintenance, repair, and enhancement. A “Persistent Asset” is defined here as any zero-g or planetary surface system that benefits from in-space assembly (ISA) or multiple visits for servicing, repairs, and upgrades. This term is an extension of the term “Persistent Platform” used by Ms. Pam Melroy at the Defense Advanced Research Projects Agency to describe the vision of the Agency for a geosynchronous Earth orbiting platform. In this paper, the term “Persistent Asset” is introduced to encompass not only zero-g systems; such as telecommunication platforms, Earth observing science platform, Department of Defense platforms, and scientific telescope systems, but also planetary surface systems that support missions such as human outposts, science stations, and in-situ resource utilization systems. In contrast to the current state of the art, where space systems are typically launched as a single unit and operated without any further physical intervention after launch; future systems will be maintained, enhanced and reconfigured in-situ as new technology becomes available or mission needs change. Visits to the persistent asset can be regularly scheduled or dictated by funding constraints enabling a pay-as-you-go approach, which is largely independent of time-constraints and able to exploit launches of opportunity. In this paper, historical in-space assembly activities which relied heavily on astronaut extra-vehicular activity will be reviewed as well as early robotic assembly activities. These approaches will be contrasted with emerging modular approaches supporting realization of a new Persistent Asset operational paradigm. The paper will define attributes of the Persistent Asset paradigm and illustrate advantages by applying the paradigm to two relevant applications: 1) a large space telescope backing structure and 2) the backbone structure for a solar electric transport vehicle. Finally, recently developed unique Persistent Asset elements (modules, and interface approaches) will be described.

Doggett, William R.↗

NASA NTRS2018

Persistent Assets in Zero-G and on Planetary Surfaces: Enabled by Modular Technology and Robotic Operations

William R Doggett↗

NASA NTRS2006

Space Studies Board Annual Report, 2006

The 2006 Annual Report of the Space Studies Board provides an opportunity to comment not only on the SSB's activities for the past year but also on the environment that has shaped those activities. As has been true for the past several years, and may well be for years to come, we live in an environment that is continually changing. NASA has continued to pursue the Vision for Space Exploration laid down by President George W. Bush in 2004, but it has obtained only limited resources to do so, requiring continuing adjustments in other NASA programs and reconsideration of our plans for the future. In this environment, the activities of the Space Studies Board are of particular importance. We can, through the National Research Council reports that we charter, provide advice on the issues most important to the execution and planning of the space program. Through our Congressional testimony and public statements, we call attention to the concerns and dilemmas that confront NASA and the science community that it supports. The Space Studies Board itself is also in transition. The year 2006 marked the arrival of a new Director, Marcia Smith, who is the permanent replacement for the long-serving and much admired Joe Alexander. As is evident in this Annual Report, Marcia has had to experience a year that has been among the busiest for the Space Studies Board. And that level of activity appears only to be increasing, as we attempt to help navigate the space program through the technical challenges and political turbulence that are expected in the years ahead.

National Aeronautics and Space Administration(NASA↗

NASA NTRS1997

New Research by CCD Scanning for Comets and Asteroids

The purpose of Spacewatch is to explore the various populations of small objects within the solar system. Spacewatch provides data for studies of comets and asteroids, finds potential targets for space missions, and provides information on the environmental problem of possible impacts. Moving objects are discovered by scanning the sky with charge-coupled devices (CCDs) on the 0.9-meter Spacewatch Telescope of the University of Arizona on Kitt Peak. Each Spacewatch scan consists of three drift scan passes over an area of sky using a CCD filtered to a bandpass of 0.5-1.0 microns (approximately V+R+I with peak sensitivity at 0.7 micron). The effective exposure time for each pass is 143 seconds multiplied by the secant of the declination. We have been finding some 30,000 new asteroids per year and applying their statistics to the study of the collisional history of the solar system. As of the end of the observing run of Nov. 1997, Spacewatch had found a total of 153 Near-Earth Asteroids (NEAs) and 8 new comets since the project began in the 1980s, and had recovered one lost comet. The total number of NEAs found by Spacewatch big enough to be hazardous if they were to impact the Earth is 36. Spacewatch is also efficient in recovery of known comets and has detected and reported positions for more than 137,000 asteroids, mostly new ones in the main belt, including more than 16,000 asteroids designated by the Minor Planet Center (MPC).

Gehrels, Tom↗

DOE OSTI2023

Possible routes to a strong science case for a joint CLEoPATRA-Roman microlensing survey

The Contemporaneous LEnsing Parallax and Autonomous TRansient Array (CLEoPATRA) is a mis sion concept for a space-based microlensing survey, proposed to enhance science for the Roman Space Telescope (RST) microlensing survey. From CLEoPATRA’s planned vantage point in geosynchronous equatorial orbit (GEO), it will observe microlensing events simultaneously and from a different point of view to RST at L2. This joint L2-GEO observation baseline gives a projected angular separation of order the size of the characteristic angular lensing scale of Free-Floating-Planets (FFPs) in the Galaxy, making it powerful for constraining FFP properties. We find that a strong science case will demonstrate which parts of the FFP parameter space a joint RST-CLEoPATRA survey will give lead ing lens constraints compared with competing ground- and space- based RST observatory companions (e.g., PRIME, Euclid). Both the simulations and framework that connect telescope capabilities to physical constraints already exist for RST FFPs and can be used to demonstrate the power of joint RST-CLEoPATRA survey, with the addition of a simulated CLEoPATRA event blending distribution. Population-level FFP constraints could also be calculated by adapting ongoing black hole microlensing research at Lawrence Livermore National Laboratory. We also find that considering CLEoPATRA as a third space-based observatory (in addition to RST and Euclid/PRIME), which will break microlensing degeneracies leading to unambiguous FFP constraints, is worth investigating as part of a science case. Finally, we highlight possible auxiliary CLEoPATRA science cases including relieving tension between the RST Core Community Surveys.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2001

Full-Time, Eye-Safe Cloud and Aerosol Lidar Observation at Atmospheric Radiation Measurement Program Sites: Instruments and Data Analysis

Atmospheric radiative forcing, surface radiation budget, and top of the atmosphere radiance interpretation involves a knowledge of the vertical height structure of overlying cloud and aerosol layers. During the last decade, the U.S. Department of Energy through I the Atmospheric Radiation Measurement (ARM) program has constructed four long- term atmospheric observing sites in strategic climate regimes (north central Oklahoma, In Barrow. Alaska, and Nauru and Manus Islands in the tropical western Pacific). Micro Pulse Lidar (MPL) systems provide continuous, autonomous observation of all significant atmospheric cloud and aerosol at each of the central ARM facilities. Systems are compact and transmitted pulses are eye-safe. Eye-safety is achieved by expanding relatively low-powered outgoing Pulse energy through a shared, coaxial transmit/receive telescope. ARM NIPL system specifications, and specific unit optical designs are discussed. Data normalization and calibration techniques are presented. A multiple cloud boundary detection algorithm is also described. These techniques in tandem represent an operational value added processing package used to produce normalized data products for Cloud and aerosol research and the historical ARM data archive.

Campbell, James R.↗

NASA NTRS2005

Determining the Locations of Brown Dwarfs in Young Star Clusters

Brown dwarfs are stellar objects with masses less than 0.08 times that of the Sun that are unable to sustain nuclear fusion. Because of the lack of fusion, they are relatively cold, allowing the formation of methane and water molecules in their atmospheres. Brown dwarfs can be detected by examining stars' absorption spectra in the near-infrared to see whether methane and water are present. The objective of this research is to determine the locations of brown dwarfs in Rho Ophiuchus, a star cluster that is only 1 million years old. The cluster was observed in four filters in the near-infrared range using the Wide-Field Infra-Red Camera (WIRC) on the 100" DuPont Telescope and Persson's Auxiliary Nasymith Infrared Camera (PANIC) on the 6.5-m Magellan Telescope. By comparing the magnitude of a star in each of the four filters, an absorption spectrum can be formed. This project uses standard astronomical techniques to reduce raw frames into final images and perform photometry on them to obtain publishable data. Once this is done, it will be possible to determine the locations and magnitudes of brown dwarfs within the cluster.

Porter, Lauren A.↗

NASA NTRS2012

Adhesive Wear of Rollers in Vacuum

This work was done to support NASA's James Webb Space Telescope that is equipped with a Near Infrared Camera and Spectrograph and Micro Shutter Assembly (MSA). A MSA mechanism's qualification test in cryogenic vacuum at 30deg K for 96K cycles resulted in roller wear and formation of some debris. Lab tests in vacuum were conducted at NASA Glenn Research Center (GRC) to understand the wear of Ti6Al4V mated with 440F steel rollers. Misalignment angle was found to have the most significant effect on debris formation. At misalignment angle of 1.4deg, significant amount of wear debris were formed within 50,000 cycles. Very few wear particles were found for a zero misalignment angle, and the total wear was small even after 367,000 cycles. The mode of wear in all the tests was attributed to adhesion, which was clearly evident from video records as well as the plate-like amalgamated debris material from both rollers. The adhesive wear rate was found to be approximately proportional to the misalignment angle. The wear is a two-way phenomenon, and the mixing of both roller materials in wear debris was confirmed by x-ray fluorescence (XRF) and EDX spectra. While there was a net loss of mass from the steel rollers, XRF and energy dispersive x-ray (EDX) spectra showed peaks of Ti on steel rollers, and peaks of Fe on Ti rollers. These results are useful for designers in terms of maintaining appropriate tolerances to avoid misalignment of rolling elements and the resulting severe wear

Shaeef, Iqbal↗