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NASA NTRS1995

The design and development of a third generation OSEE instrument

Optically Stimulated Electron Emission (OSEE) has been used to quantify surface contamination in the aerospace community. As advances are made towards the understanding of OSEE, it is desirable to incorporate technological advances with succeeding generations of instrumentation, so that improvements in the practical application of OSEE may be disseminated among the user community. Several studies undertaken by Yost, Welch, Abedin and others have expanded the knowledge base related to the underlying principles of OSEE. The conclusions of these studies, together with inputs from the user community were the foundation upon which the development of a third generation OSEE instrument was based. This manuscript describes the significant improvements incorporated into a third generation OSEE instrument as well as the elements unique to its design.

Perey, D. F.↗

NASA NTRS1994

Feasibility of an integrated X-ray instrument for Mars exobiology and geology

By employing an integrated X-ray instrument on a future Mars mission, data obtained will greatly augment those returned by Viking; details relevant to the possibility of the origin and evolution of life on Mars will be acquired. An integrated combined X Ray Fluorescence/X Ray Detection (XRF/XRD) instrument has been breadboarded and demonstrated to accommodate important exobiology and geology experiment objectives outlined for Mars Environmental Survey (MESUR) and future Mars missions. Among others, primary objectives for the exploration of Mars include: the intense study of local areas on Mars to 'establish the chemical, mineralogical, and petrological character of different components of the surface material; to determine the distribution, abundance and sources and sinks of volatile materials, including an assessment of the biologic potential, now and during past epochs; and to establish the global chemical and physical characteristics of the Martian surface'. The XRF/XRD breadboard instrument identifies and quantifies soil surface elemental, mineralogical, and petrological characteristics and acquires data necessary to address questions on volatile abundance and distribution. Additionally, the breadboard is able to characterize the biogenic element constituents of soil samples providing information on the biologic potential of the Mars environment.

Fonda, M. L.↗

NASA NTRS1993

The extreme ultraviolet spectrograph: A radial groove grating, sounding rocket-borne, astronomical instrument

The design, calibration, and sounding rocket flight performance of a novel spectrograph suitable for moderate-resolution EUV spectroscopy are presented. The sounding rocket-borne instrument uses a radial groove grating to maintain a high system efficiency while controlling the aberrations induced when doing spectroscopy in a converging beam. The instrument has a resolution of approximately 2 A across the 200-330 A bandpass with an average effective area of 2 sq cm. The instrument, called the Extreme Ultraviolet Spectrograph, acquired the first EUV spectra in this wavelength region of the hot white dwarf G191-B2B and the late-type star Capella.

Wilkinson, Erik↗

NASA NTRS1994

Flight experience with lightweight, low-power miniaturized instrumentation systems

Engineers at the NASA Dryden Flight Research Facility (NASA-Dryden) have conducted two flight research programs with lightweight, low-power miniaturized instrumentation systems built around commercial data loggers. One program quantified the performance of a radio-controlled model airplane. The other program was a laminar boundary-layer transition experiment on a manned sailplane. The purpose of this article is to report NASA-Dryden personnel's flight experience with the miniaturized instrumentation systems used on these two programs. This article will describe the data loggers, the sensors, and the hardware and software developed to complete the systems. It also describes how the systems were used and covers the challenges encountered to make them work. Examples of raw data and derived results will be shown as well. For some flight research applications where miniaturized instrumentation is a requirement, the authors conclude that commercially available data loggers and sensors are viable alternatives. In fact, the data loggers and sensors make it possible to gather research-quality data in a timely and cost-effective manner.

LOW POWER MINIATURIZED INSTRUM↗

NASA NTRS1995

Calibration and postlaunch performance of the Meteor 3/TOMS instrument

Prelaunch and postlaunch calibration results for the Meteor 3/total ozone mapping spectrometer (TOMS) instrument are presented here. Ozone amounts are retrieved from measurements of Earth albedo in the 312- to 380-nm range. The accuracy of albedo measurements is primarily tied to knowledge of the reflective properties of diffusers used in the calibrations and to the instrument's wavelength selection. These and other important prelaunch calibrations are presented. Their estimated accuracies are within the bounds necessary to determine column ozone to better than 1%. However, postlaunch validation results indicate some prelaunch calibration uncertainties may be larger than originally estimated. Instrument calibrations have been maintained postlaunch to within a corresponding 1% error in retrieved ozone. Onboard calibrations, including wavelength monitoring and a three-diffuser solar measurement system, are described and specific results are presented. Other issues, such as the effects of orbital precession on calibration and recent chopper wheel malfunctions, are also discussed.

Jaross, G.↗

NASA NTRS1993

An intercomparison of aircraft instrumentation for tropospheric measurements of sulfur dioxide

As part of the NASA Tropospheric Chemistry Program, a series of field intercomparisons have been conducted to evaluate the state-of-the art for measuring key tropospheric species. One of the objectives of the third intercomparison campaign in this series, Chemical Instrumentation Test and Evaluation 3 (CITE 3), was to evaluate instrumentation for making reliable tropospheric aircraft measurements of sulfur dioxide, dimethyl sulfide, hydrogen sulfide, carbon disulfide, and carbonyl sulfide. This paper reports the results of the intercomparisons of five sulfur dioxide measurement methods ranging from filter techniques, in which samples collected in flight are returned to the laboratory for analyses (chemiluminescent or ion chromatographic), to near real-time, in-flight measurements via gas chromatographic, mass spectrometric, and chemiluminescent techniques. All techniques showed some tendency to track sizeable changes in ambient SO2 such as those associated with altitude changes. For SO2 mixing ratios in the range of 200 pptv to a few ppbv, agreement among the techniques varies from about 30% to several orders of magnitude, depending upon the pair of measurements intercompared. For SO2 mixing ratios less than 200 pptv, measurements from the techniques are uncorrelated. In general, observed differences in the measurement of standards do not account for the flight results. The CITE 3 results do not unambiguously identify one or more of the measurement techniques as providing valid or invalid SO2 measurements, but identify the range of 'potential' uncertainty in SO2 measurements reported by currently available instrumentation and as measured under realistic aircraft environments.

Gregory, Gerald L.↗

NASA NTRS1993

An intercomparison of aircraft instrumentation for tropospheric measurements of carbonyl sulfide, hydrogen sulfide, and carbon disulfide

This paper reports results of NASA's Chemical Instrumentation and Test Evaluation (CITE 3) during which airborne measurements for carbonyl sulfide (COS), hydrogen sulfide (H2S), and carbon disulfide (CS2) were intercompared. Instrumentation included a gas chromatograph using flame photometric detection (COS, H2S, and CS2), a gas chromatograph using mass spectrometric detection (COS) and CS2), a gas chromatograph using fluorination and subsequent SF6 detection via electron capture (COS and CS2), and the Natusch technique (H2S). The measurements were made over the Atlantic Ocean east of North and South America during flights from NASA's Wallops Flight Center, Virginia, and Natal, Brazil, in August/September 1989. Most of the intercomparisons for H2S and CS2 were at mixing ratios less than 25 pptv and less than 10 pptv, respectively, with a maximum mixing ratio of about 100 pptv and 50 pptv, respectively. Carbonyl sulfide intercomparisons were at mixing ratios between 400 and 600 pptv. Measurements were intercompared from data bases constructed from time periods of simultaneous or overlapping measurements. Agreement among the COS techniques averaged about 5%, and individual measurements were generally within 10%. For H2S and at mixing ratio greater than 25 pptv, the instruments agreed on average to about 15%. At mixing ratios less than 25 pptv the agreement was about 5 pptv. For CS2 (mixing ratios less than 50 pptv), two techniques agreed on average to about 4 pptv, and the third exhibited a bias (relative to the other two) that varied in the range of 3-7 pptv. CS2 mixing ratios over the ocean east of Natal as measured by the gas chromatograph-mass spectrometer technique were only a few pptv and were below the detection limits of the other two techniques. The CITE 3 data are used to estimate the current uncertainty associated with aircraft measurements of COS, H2S, and CS2 in the remote troposphere.

Gregory, Gerald L.↗

NASA NTRS1994

Comment on 'Intercalibration of solar wind instruments during the International Magnetospheric Study' by S. M. Petrinec and C. T. Russell

In their paper Petrinec and Russell (PR) (1993) claim to have developed a 'more homogeneous and accurate set of solar wind data' by 'correcting' the reported ion densities from three plasma instruments: the Los Alamos National Laboratory (LANL) ion electrostatic analyzer on ISEE 3 and the LANL electrostatic analyzer and the Massachusetts Institute of Technology (MIT) Faraday cup plasma instrument on Interplanetary Monitoring Platform 8 (IMP 8). Their data manipulation techniques are examined. The foundations on which their data set are built, are discussed. Reanalysis by MIT on the MIT instrument (IMP 8) was done. Initial results have been issued. The Petrinec & Russell (1993) (PR) paper does not provide accurate density estimates and is an exercise that will only bring confusion to users of the data. The results of PR should be treated with skepticism.

Paularena, K. I.↗

NASA NTRS1992

The high resoultion dynamics limb sounder (HIRDLS): An instrument for the study of global change

Two groups, in the Unites States and the United Kingdom, proposed to further develop and use infrared limb scanning instruments in atmospheric studies from Earth Observing System (EOS). Subsequent review showed that the scientific objectives and basic measurement approaches were very similar, although there were differences in the proposed instrumentation. Their teams agreed to merge the two investigations into the High Resolution Dynamics Limb Sounder (HIRDLS). Under the resulting understanding, the two teams have combined, and will produce a single design to satisfy the scientific requirements of their investigations. The characteristics of limb scanning and earlier experiments are reviewed. The HIRDLS scientific objectives and requirements on the derived geophysical quantities are presented, and the way in which they drive the design of HIRDLS is indicated. A brief description of the HIRDLS instrument and a summary of HIRDLS capabilities follow.

Gille, J. C.↗

NASA NTRS1995

Long-Lived Linear-Motion Suspension For Cryogenic Instrument

Mechanism suspends optical component in cryogenic instrument in such way to allow component to translate smoothly along one axis, without vibration. Bearings located outside cooled instrument chamber for longer life. Thermal isolators separate bearings from cryogenic environment inside instrument chamber.

Packard, Douglas T.↗

NASA NTRS1995

Instrument technology for magnetosphere plasma imaging from high Earth orbit. Design of a radio plasma sounder

The use of radio sounding techniques for the study of the ionospheric plasma dates back to G. Briet and M. A. Tuve in 1926. Ground based swept frequency sounders can monitor the electron number density (N(sub e)) as a function of height (the N(sub e) profile). These early instruments evolved into a global network that produced high-resolution displays of echo time delay vs frequency on 35-mm film. These instruments provided the foundation for the success of the International Geophysical Year (1958). The Alouette and International Satellites for Ionospheric Studies (ISIS) programs pioneered the used of spaceborne, swept frequency sounders to obtain N(sub e) profiles of the topside of the ionosphere, from a position above the electron density maximum. Repeated measurements during the orbit produced an orbital plane contour which routinely provided density measurements to within 10%. The Alouette/ISIS experience also showed that even with a high powered transmitter (compared to the low power sounder possible today) a radio sounder can be compatible with other imaging instruments on the same satellite. Digital technology was used on later spacecraft developed by the Japanese (the EXOS C and D) and the Soviets (Intercosmos 19 and Cosmos 1809). However, a full coherent pulse compression and spectral integrating capability, such as exist today for ground-based sounders (Reinisch et al., 1992), has never been put into space. NASA's 1990 Space Physics Strategy Implementation Study "The NASA Space Physics Program from 1995 to 2010" suggested using radio sounders to study the plasmasphere and the magnetopause and its boundary layers (Green and Fung, 1993). Both the magnetopause and plasmasphere, as well as the cusp and boundary layers, can be observed by a radio sounder in a high-inclination polar orbit with an apogee greater than 6 R(sub e) (Reiff et al., 1994; Calvert et al., 1995). Magnetospheric radio sounding from space will provide remote density measurements of unprecedented precision and coverage in the plasmasphere, inner magnetosphere and magnetopause, from which the structure, inter-relationship, and variations of different plasma regions can be determined (Armstrong Johnson, 1995). A space-borne Radio Plasma Imager (RPI) could provide a unique global view of the magnetosphere revealing the underlying structure of remote plasma regions, thereby providing a framework for the interpretation of images obtained by other techniques as identified in the technical areas TA1 to TA4 in the MSFC NRA8-8.

Haines, D. Mark↗

NASA NTRS1995

ASTRO-2 Spacelab Instrument Pointing System mission performance

This paper reports the performance of the Instrument Pointing System (IPS) that flew on the National Aeronautics and Space Administration (NASA) ASTRO-2 Spacelab mission aboard the Space Shuttle Endeavour in March 1995. The IPS provides a stabilizing platform for the ASTRO-2 instrument payload complement that consists of three main experiments (telescopes). The telescopes observe stellar targets in the universe within the ultraviolet portion of the electromagnetic spectrum that must be observed from beyond the earth's atmospheric filtering effects. The three main experiments for observation are the Hopkins Ultraviolet Telescope (HUT), the Ultraviolet Imaging Telescope (UIT), and the Wisconsin Ultraviolet Photo-Polarimetry Experiment (WUPPE). The HUT uses spectroscopy to obtain the structure and chemical makeup of ultraviolet targets. UIT is responsible for wide field photographing to capture the hidden view of the ultraviolet universe. The WUPPE gathers data on the polarization of the ultraviolet electromagnetic energy coming from the astronomical targets. The capability of IPS enables the experiments to 'see' faint celestial objects. A brief explanation of the IPS is given followed by a review of engineering efforts to improve IPS performance over the ASTRO-1 mission. The main focus of improvements was on enhancing the star acquisition capability through improved guide star selection, lab simulations, computer upgrades, data display systems improvements, and software modifications. A star simulator was developed in the lab to enable IPS to be simulated on the ground pre-mission with flight hardware and software in the loop. The paper concludes with results from the ASTRO-2 mission. The number of targets acquired and the IPS pointing accuracy/stability is reported along with recommendations for the future use of the Instrument Pointing System.

Wessling, Francis C., III↗

NASA NTRS1996

Airborne Instruments for the In Situ Detection of ClONO2, NO2, ClO, and BrO in the Stratosphere

Design and construction of an in situ sensor for the detection of stratospheric ClONO2, ClO, BrO, and NO2, was conceived as a two-year program. The experiment has two novel components: a resistive silicon thermal dissociation heater used to fragment ClONO2 into ClO and NO2 and a laser-induced fluorescence sensor for N02. These two new components are integrated into an experiment that uses technology developed in our labs for the ER-2 ClO and ER-2 HO(X) instruments. During the first year we reconstructed our laboratory prototypes for ClONO2 and NO2 detection and made substantial improvements in the calibration apparatus. Results from these laboratory experiments have been used to refine the design of the flight instrument. During this year we began the design of all of the long-lead items required to produce a flight instrument: including the design and fabrication of the air flow system used to direct stratospheric air to our halogen sensors, design and prototyping of an aircraft-compatible thermal dissociation heater, and development and test of a new high powered laser system. Finally, we have designed and released for fabrication several subsystems.

Anderson, James G.↗

NASA NTRS1995

The Polar Plasma Wave Instrument

The Plasma Wave Instrument on the Polar spacecraft is designed to provide measurements of plasma waves in the Earth's polar regions over the frequency range from 0.1 Hz to 800 kHz. Three orthogonal electric dipole antennas are used to detect electric fields, two in the spin plane and one aligned along the spacecraft spin axis. A magnetic loop antenna and a triaxial magnetic search coil antenna are used to detect magnetic fields. Signals from these antennas are processed by five receiver systems: a wideband receiver, a high-frequency waveform receiver, a low-frequency waveform receiver, two multichannel analyzers; and a pair of sweep frequency receivers. Compared to previous plasma wave instruments, the Polar plasma wave instrument has several new capabilities. These include (1) an expanded frequency range to improve coverage of both low- and high-frequency wave phenomena, (2) the ability to simultaneously capture signals from six orthogonal electric and magnetic field sensors, and (3) a digital wideband receiver with up to 8-bit resolution and sample rates as high as 249k samples s(exp -1).

Gurnett, D. A.↗

NASA NTRS1995

Elemental composition in the slow solar wind measured with the MASS instrument on WIND

The MASS instrument on WIND contains the first isochronous time-offlight spectrometer to be flown in the solar wind. The first spectra obtained with this instrument has demonstrated its capability to measure the abundances of several high-and low-FIP elements in the solar wind. The derivation of these abundances requires a careful calibration of the charge exchange efficiencies of the relevant ions in carbon foils. These efficiencies and the corresponding instrument functions have been determined in extensive calibration campaigns at different institutions. We present first and preliminary results obtained in slow solar wind streams and we compare these results with those obtained from previous investigations of solar wind abundances and of coronal abundances as derived from Solar Energetic Particles. Recent models of the FIP related fractionation effect predict a depletion of a factor of typically 4 to 5 for high-FIP elements (He, N, O, Ne, Ar, etc.) relative to low-FIP elements (Mg, Fe, Si, etc.). We also compare our results with the detailed predictions of the different models and we discuss the resulting evidence to validate or to invalidate different physical scenarios explaining the feeding and the acceleration of slow stream solar wind.

Bochsler, P.↗

NASA NTRS1995

Elemental and charge state composition of the fast solar wind observed with SMS instruments on WIND

The elemental composition and charge state distributions of heavy ions of the solar wind provide essential information about: (1) atom-ion separation processes in the solar atmosphere leading to the 'FIP effect' (the overabundance of low First Ionization potential (FIP) elements in the solar wind compared to the photosphere); and (2) coronal temperature profiles, as well as mechanisms which heat the corona and accelerate the solar wind. This information is required for solar wind acceleration models. The SWICS instrument on Ulysses measures for all solar wind flow conditions the relative abundance of about 8 elements and 20 charge states of the solar wind. Furthermore, the Ulysses high-latitude orbit provides an unprecedented look at the solar wind from the polar coronal holes near solar minimum conditions. The MASS instrument on the WIND spacecraft is a high-mass resolution solar wind ion mass spectrometer that will provide routinely not only the abundances and charge state of all elements easily measured with SWICS, but also of N, Mg, S. The MASS sensor was fully operational at the end of 1994 and has sampled the in-ecliptic solar wind composition in both the slow and the corotating fast streams. This unique combination of SWICS on Ulysses and MASS on WIND allows us to view for the first time the solar wind from two regions of the large coronal hole. Observations with SWICS in the coronal hole wind: (1) indicate that the FIP effect is small; and (2) allow us determine the altitude of the maximum in the electron temperature profile, and indicate a maximum temperature of approximately 1.5 MK. New results from the SMS instruments on Wind will be compared with results from SWICS on Ulysses.

Gloeckler, G.↗

NASA NTRS1996

Using Fast-Steering Mirror Control to Reduce Instrument Pointing Errors Caused by Spacecraft Jitter

The scope of this study was to investigate the benefit of using feedback control of a Fast Steering Mirror (FSM) to reduce instrument pointing errors. Initially, the study identified FSM control technologies and categorized them according to their use, range of applicability, and physical requirements. Candidate payloads were then evaluated according to their relevance in use of fast steering minor control technologies. This leads to the mission and instrument selection which served as the candidate mission for numerical modeling. A standard SmallSat was designed in order to accommodate the payload requirements (weight, size, power, etc.). This included sizing the SmallSat bus, sizing the solar array, choosing appropriate antennas, and identifying an attitude control system (ACS). A feedback control system for the FSM compensation was then designed, and the instrument pointing error and SmallSat jitter environment for open-loop and closed-loop FSM control were evaluated for typical SmallSat disturbances. The results were then compared to determine the effectiveness of the FSM feedback control system.

Antol, Jeffery↗

NASA NTRS1995

Subminiaturization for ERAST instrumentation (Environmental Research Aircraft and Sensor Technology)

We are focusing on the Argus as an example to demonstrate our philosophy on miniaturization of airborne analytical instruments for the study of atmospheric chemistry. Argus is a two channel, tunable-diode laser absorption spectrometer developed at NASA for the measurement of nitrogen dioxide (N2O) (4.5 micrometers) and ammonia (CH3) (3.3 micrometers) at the 0.1 parts per billion (ppb) level from the Perseus aircraft platform at altitudes up to 30 km. Although Argus' mass is down to 23 kg from the 197 kg Atlas, its predecessor, our goal is to design a next-generation subminiaturized instrument weighing less than 1 kg, measuring a few cm(exp 3) and able to eliminate dewars for cooling. Current designs enable use to make a small,inexpensive, monolithic spectrometer without the required sensitivity range. Further work is on its way to increase sensitivity. We are continuing to zero-base the technical approach in terms of the specifications for the given instrument. We are establishing a check list of questions to hone into the best micromachining approach and to superpose on the answers insights in scaling laws and flexible engineering designs to enable more relaxed tolerances for the smallest of the components.

Madou, Marc↗