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At least 109 records · Page 6

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NASA NTRS1987

SAGE II aerosol extinction and scattering data from balloon-borne photography

Earth limb radiance and extinction near sunset have been observed from a balloon-borne gondola nearly simultaneously and on air masses close to those probed by the SAGE II instrumentation on April 22, 1985. The results show the importance of accuracy of the altitude determination on the aerosol measurements. They indicate an important altitude dependence of the stratospheric aerosol granulometry in agreement with SAGE II results.

Ackerman, M.↗

NASA NTRS1987

Measurement of stratospheric trace constituent distributions from balloon-borne far infrared observations

FIR limb thermal emission spectra obtained from balloon-borne measurements made as a part of the Balloon Intercomparison Campaign (BIC) have been analyzed for retrieval of stratospheric trace-constituent distributions. The measurements were made with a high-resolution Michelson interferometer and covered the 15-180/cm spectral range with an unapodized spectral resolution of 0.0033/cm. The retrieved vertical profiles of O3, H2O, HDO, HCN, CO, and isotopes of O3 are presented. The results are compared with the BIC measurements for O3 and H2O made from the same balloon gondola and with other published data. A comparison of the simultaneously retrieved profiles for several gases with the published data shows good agreement and indicates the validity of the FIR data and retrieval techniques and the accuracy of the inferred profiles.

Abbas, M. M.↗

NASA NTRS1987

Meteorological variations in the middle clouds of Venus from Vega balloon in situ measurements

Instruments aboard the gondolas of the two Vega balloons obtained in situ measurements of pressure, temperature, vertical velocity relative to the balloon, cloud particle backscatter, lightning and the ambient light level. Atmospheric motions at the balloon float altitudes were also determined from earth-based tracking results. To illustrate the history of the balloon flights and to facilitate comparisons between some of the different observed quantities, measurements of pressure, temperature and backscatter are presented as time series for the entire lifetime of each balloon. Both long and short period variations have been detected. In addition, the environmental entropy encountered by each balloon will be discussed.

Elson, Lee S.↗

NASA NTRS1988

In-situ detection of OH in the lower stratosphere with a balloon borne high repetition rate laser system

Midday stratospheric OH density measurements have been carried out within the altitude interval of 31 to 24 km using the laser-induced fluorescence technique deployed on a balloon-borne gondola launched from Palestine, Texas on July 15, 1987. Laser output at 282 nm is produced with a pulsed, 17 kHz repetition rate, copper vapor laser pumped tunable dye laser. The OH mixing ratio ranged from 16 + or - 5 ppt at 31 km to 4 + or - 3 ppt in the 27 to 24 km region. Simultaneous ozone and water vapor measurements were also obtained with separate instruments.

Stimpfle, R. M.↗

NASA NTRS1989

Balloon borne in-situ detection of OH in the stratosphere from 37 to 23 km

The OH number density in the stratosphere has been measured over the altitude interval of 37 to 23 km at midday via a balloon-borne gondola launched from Palestine, Texas on July 6, 1988. OH radicals are detected with a laser-induced fluorescence instrument employing a 17-kHz-repetition-rate copper vapor laser-pumped dye laser optically coupled to an enclosed flow, in-situ sampling chamber. OH abundances ranged from 88 + or - 3l pptv in the 36 to 35 km interval to 0.9 + or - 0.8 pptv in the 24 to 23 km interval. The stated uncertainty includes that from both measurement precision and accuracy. Simultaneous detection of ozone and water vapor densities was carried out with separate on-board instruments.

Stimpfle, R. M.↗

NASA NTRS1990

High resolution solar spectrometer system for measuring atmospheric constituents

A mid-IR Michelson interferometer capable of obtaining 0.002/cm resolution solar spectra has been developed for balloon use. The interferometer is based on the Bomem self-aligning instrument, and is equipped with a solar tracking system, telemetry, and recording systems, as well as temperature control and gondola orientation. The interferometer has made two successful flights in the 7-14-micron interval up to 40 km. The basic systems are described and sample spectra are presented.

Murcray, Frank J.↗

NASA NTRS1990

A cryogenically cooled photofragment fluorescence instrument for measuring stratospheric water vapor

An instrument developed for high-resolution daytime measurements of water vapor in the stratosphere using the technique of photofragment fluorescence is examined. A detailed description of all aspects of the instrument, as well as the results of its first two flights, are presented. The main areas of concern were optical baffling, cryogen transfer, water vapor measurement without contamination, and a dual path absorption measurement. Results of the second flight test indicate that the problems of instrument and gondola contamination, identified in the first flight test, were solved. A signal-to-noise ratio of about 50:1 for 10 sec of averaging throughout the stratosphere is achieved, as well as an altitude resolution of better than 100 m.

Weinstock, Elliot M.↗

NASA NTRS1990

The Balloon Intercomparison Campaigns - An introduction and overview

The Balloon Intercomparison Campaigns of 1982 and 1983 involved a comparison of measurements by 21 instruments from seven countries, assembled on four gondolas, assigned to collect data on the vertical profiles of HCl, HNO3, NO2, NO, O3, and many other stratospheric constituents. Most of these sensors supplied data on more than two constituents. This paper describes the instruments and the constituents measured by each of the sensor and the parameters of each balloon flight, together with some results.

Watson, R. T.↗

NASA NTRS1990

In situ measurement of water vapor in the stratosphere with a cryogenically cooled Lyman-alpha hygrometer

In situ measurements of water vapor in the stratosphere with a new instrument are reported. The instrument has been designed to observe daytime water vapor from a multiinstrument balloon gondola that simultaneously measures free radicals such as OH, HO2, and O3 in the stratosphere up to 40 km. Lyman-alpha photofragment fluorescence is used to measure water molecules in a flowing sample of ambient air. A brief description of the instrument is given, followed by the results of the first four balloon flights. The measured mixing ratio for this flight varies from 3.0-5.5 ppmv over the altitude range of 17-34 km. Adjustments in the cooling protocol for the flights of July 6, 1988, July 28, and August 25, 1989, result in a much higher signal-to-noise ratio. Profiles from these three flights are similar to, but somewhat higher, than the 1987 profile. Implications of measurements are discussed, as are the issues of short- and long-term variability of stratospheric water vapor.

Schwab, J. J.↗

NASA NTRS1991

Unbalanced Rotating Masses For Scanning

Unbalanced rotating masses low-cost, low-power, lightweight means of generating scanning torques for scientific instruments. Imparts variety of scanning patterns; continuous circular, back-and-forth linear, and, with aid of indexing mechanism, raster. Scanning rate determined by sizes of moment arms and rotational velocities. System of unbalanced rotating masses proposed for scanning gimbaled sensors that observe Sun from balloon-borne gondola. Two unbalanced masses move sensor aim in circular pattern around center of the Sun.

Polites, Michael E.↗

NASA NTRS1991

Oxygen isotope fractionation in stratospheric CO2

A new cryogenic collection system has been flown on board a balloon gondola to obtain separate samples of ozone and carbon dioxide without entrapping major atmospheric gases. Precision laboratory isotopic analysis of CO2 samples collected between 26 and 35.5 km show a mass-independent enrichment in both O-17 and O-18 of about 11 per mil above tropospheric values. Ozone enrichment in its heavy isotopes was 9 to 16 percent in O3-50 and 8 to 11 percent in O3-49, respectively (Schueler et al., 1990). A mechanism to explain the isotope enrichment in CO2 has been recently proposed by Yung et al. (1991). The model is based on the isotope exchange between CO2 and O3 via O(1D), resulting in a transfer of the ozone isotope enrichment to carbon dioxide. Predicted enrichment and measured values agree well.

Thiemens, M. H.↗

NASA NTRS1991

A balloon-borne payload for imaging hard X-rays and gamma rays from solar flares

Hard X-rays and gamma rays provide direct evidence of the roles of accelerated particles in solar flares. An approach that employs a spatial Fourier-transform technique for imaging the sources of these emissions is described, and the development of a balloon-borne imaging device based on this instrumental technique is presented. The detectors, together with the imaging optics, are sensitive to hard X-ray and gamma-ray emission in the energy-range from 20 to 700 keV. This payload, scheduled for its first flight in June 1992, will provide 11-arc second angular resolution and millisecond time resolution with a whole-sun field of view. For subsequent flights, the effective detector area can be increased by as much as a factor of four, and imaging optics with angular resolution as fine as 2 arcsec can be added to the existing gondola and metering structures.

Crannell, Carol J.↗

NASA NTRS1991

Joint US-USSR Long duration Antarctic Mars calibration Balloon (LAMB) mission

The Long duration Antarctic Mars calibration Balloon (LAMB) project has been established at Goddard Space Flight Center for the evaluation and cross calibration of U.S. and USSR remote sensing gamma-ray and neutron detectors. These detectors are analogs of those flown on the Soviet Phobos mission around Mars and those to be flown on the upcoming U.S. Mars Observer mission. Cosmic rays, which are normally filtered out by the atmosphere, and the earth's magnetic field, will induce gamma-ray and neutron emissions from about a half ton of simulated Mars soil aboard the gondola. The cross calibration of these instruments should greatly facilitate the data analysis from both missions and play a role in U.S.-USSR cooperation in space.

Floyd, S. R.↗

NASA NTRS1991

Recovery system termination load reduction through the use of a central load core

A study is presented of the development and testing of a parachute central load core, an adaptive device whose primary function is to minimize parachute stored elastic energy while providing adequate rotational stiffness to prevent shroud line fouling from twisting and sufficient resistive torque for any balloon gondola positioning requirements. Empirical relations are given for the uninhibited drag area growth which are derived in the classical nondimensional form. Attention is given to development considerations and design along with model simulations, small and midscale drop test data, full-scale flight data, and instrumentation applications.

Robbins, ED↗

NASA NTRS1991

EXITE/IPC observations of SN1987A and southern targets

The Energetic X-ray Imaging Telescope Experiment (EXITE) was developed to a flight-ready status and conducted two flights (May 18, 1988, and May 8-10, 1989) from Alice Springs, Australia, as part of the campaigns to observe the supernova SN1987A. The basic operation of the detector and gondola systems in the laboratory was tested on the first flight and found to meet expected performance values. A bizarre 'balloon tape' insulation problem, however, prevented normal telescope pointing on the first flight so no data on SN1987A or other targets were obtained. Following a successful second EXITE flight from Ft. Sumner, NM, in October 1988, the experiment was flown again on a successful 30 hour flight as part of the final 1989 supernova campaign. A second x-ray imaging experiment from MSFC was also flown (piggy-back) for this third flight. Good data were obtained on the supernova and a variety of high priority galactic targets, and final analysis is still in progress. Preliminary results from this flight are presented.

Grindlay, Jonathan E.↗

NASA NTRS1989

Feasibility study of a long duration balloon flight with NASA/GSFC and Soviet Space Agency Gamma Ray Spectrometers

A feasibility study of conducting a joint NASA/GSFC and Soviet Space Agency long duration balloon flight at the Antarctic in Jan. 1993 is reported. The objective of the mission is the verification and calibration of gamma ray and neutron remote sensing instruments which can be used to obtain geochemical maps of the surface of planetary bodies. The gamma ray instruments in question are the GRAD and the Soviet Phobos prototype. The neutron detectors are supplied by Los Alamos National Laboratory and the Soviet Phobos prototype. These are to be carried aboard a gondola that supplies the data and supplies the power for the period of up to two weeks.

Sharp, William E.↗

NASA NTRS1993

Scientific ballooning payload termination loads

NASA's high altitude balloon borne scientific payloads are typically suspended from a deployed flat circular parachute. At flight termination, the recovery train is pyrotechnically separated at the parachute apex and balloon nadir interface. The release of elastic energy stored in the parachute at zero initial vertical velocity in the rarefied atmosphere produces high canopy opening forces that subject the gondola to potentially damaging shock loads. Data from terminations occurring at altitudes to 40 km with payloads up to 2500 kg on parachutes up to 40 m in diameter are presented. Measured loads are markedly larger than encountered via packed parachute deployment for similar canopy loadings. Canopy inflation is significantly suppressed in the early stages and then accelerated during final blossoming. Data interpretation and behavioral phenomena are discussed along with proposed shock attenuation techniques.

Robbins, E.↗

NASA NTRS1993

Multiorder etalon sounder (MOES) development and test for balloon experiment

The Fabry-Perot interferometer (FPI), with its high throughput and high spectral resolution has been used in the remote-sensing measurements of the earth's atmospheric composition, winds, and temperatures. The most recent satellite instruments include the Fabry-Perot interferometer flown on the Dynamics Explorer-2 (DE-2), the High Resolution Doppler Imager (HRDI), and the Cryogenic Limb Array Etalon Spectrometer (CLAES) flown on the Upper Atmosphere Research Satellite (UARS). These instruments measure the Doppler line profiles of the emission and absorption of certain atmospheric species (such as atomic oxygen) in the visible and infrared spectral region. The successful space flight of DE-FPI, HRDI, and CLAES on UARS demonstrated the extremely high spectral resolution and ruggedness of the etalon system for the remote sensing of earth and planetary atmospheres. Recently, an innovative FPI focal plane detection technique called the Circle-to-Line Interferometer Optical (CLIO) system was invented at the Space Physics Research Laboratory. The CLIO simplifies the FPI focal plane detection process by converting the circular rings or fringes into a linear pattern similar to that produced by a conventional spectrometer, while retaining the throughput advantage of the etalon interferometer. The combination of FPI and CLIO allows the development of more sensitive Fabry-Perot interferometers in the infrared for the remote sensing of the lower atmospheres of Earth and possibly other planets. The Multiorder Etalon Sounder (MOES), a combination of the rugged etalon and the CLIO, compares very favorably to other space-borne optical instruments in terms of performance versus complexity. The new instrument is expected to be rugged, compact, and very suitable for an operational temperature and moisture sounder. With this technique, the contamination of radiance measurements by emissions of other gases is also minimized. At the Space Physics Research Laboratory (SPRL), the MOES concept and laboratory experiments were worked on for the past several years. Both theoretical studies and laboratory prototype experiments showed that MOES is very competitive compared with other high resolution sounders in terms of complexity and performance and has great potential as a compact and rugged high resolution atmospheric temperature and trace species sounder from the polar platform or the geostationary platform. The logical next step is to convert our laboratory prototype to a balloon instrument, so that field test of MOES can be carried out to prove the feasibility and capability of this new technology. Some of the activities related to the development of MOES for a possible balloon flight demonstration are described. Those research activities include the imaging quality study on the CLIO, the design and construction of a MOES laboratory prototype, the test and calibration of the MOES prototype, and the design of the balloon flight gondola.

Hays, Paul B.↗