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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Validation of MIPAS IMK-IAA Temperature, Water Vapor, and Ozone Profiles with MOHAVE-2009 Campaign Measurements

MIPAS observations of temperature, water vapor, and ozone in October 2009 as derived with the scientific level-2 processor run by Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK) and CSIC, Instituto de Astrofısica de Andalucıa (IAA) and retrieved from version 4.67 level-1b data have been compared to co-located field campaign observations obtained during the MOHAVE-2009 campaign at the Table Mountain Facility near Pasadena, California in October 2009. The MIPAS measurements were validated regarding any potential biases of the profiles, and with respect to their precision estimates. The MOHAVE-2009 measurement campaign provided measurements of atmospheric profiles of temperature, water vapor/relative humidity, and ozone from the ground to the mesosphere by a suite of instruments including radiosondes, ozonesondes, frost point hygrometers, lidars, microwave radiometers and Fourier transform infrared (FTIR) spectrometers. For MIPAS temperatures (version V4O_T_204), no significant bias was detected in the middle stratosphere; between 22 km and the tropopause MIPAS temperatures were found to be biased low by up to 2 K, while below the tropopause, they were found to be too high by the same amount. These findings confirm earlier comparisons of MIPAS temperatures to ECMWF data which revealed similar differences. Above 12 km up to 45 km, MIPAS water vapor (version V4O_H2O_203) is well within 10% of the data of all correlative instruments. The well-known dry bias of MIPAS water vapor above 50 km due to neglect of non-LTE effects in the current retrievals has been confirmed. Some instruments indicate that MIPAS water vapor might be biased high by 20 to 40% around 10 km (or 5 km below the tropopause), but a consistent picture from all comparisons could not be derived. MIPAS ozone (version V4O_O3_202) has a high bias of up to +0.9 ppmv around 37 km which is due to a non-identified continuum like radiance contribution. No further significant biases have been detected. Cross-comparison to co-located observations of other satellite instruments (Aura/MLS, ACE-FTS, AIRS) is provided as well.

MIPAS validation↗
NASA NTRS2008

Formation of Large (Approximately 100 micrometers) Ice Crystals Near the Tropical Tropopause

Recent high-altitude aircraft measurements with in situ imaging instruments indicated the presence of relatively large (approx.100 microns length), thin (aspect ratios of approx.6:1 or larger) hexagonal plate ice crystals near the tropical tropopause in very low concentrations (<0.01/L). These crystals were not produced by deep convection or aggregation. We use simple growth-sedimentation calculations as well as detailed cloud simulations to evaluate the conditions required to grow the large crystals. Uncertainties in crystal aspect ratio leave a range of possibilities, which could be constrained by knowledge of the water vapor concentration in the air where the crystal growth occurred. Unfortunately, water vapor measurements made in the cloud formation region near the tropopause with different instruments ranged from <2 ppmv to approx.3.5 ppmv. The higher water vapor concentrations correspond to very large ice supersaturations (relative humidities with respect to ice of about 200%). If the aspect ratios of the hexagonal plate crystals are as small as the image analysis suggests (6:1, see companion paper (Lawson et al., 2008)) then growth of the large crystals before they sediment out of the supersaturated layer would only be possible if the water vapor concentration were on the high end of the range indicated by the different measurements (>3 ppmv). On the other hand, if the crystal aspect ratios are quite a bit larger (approx.10:1), then H2O concentrations toward the low end of the measurement range (approx.2-2.5 ppmv) would suffice to grow the large crystals. Gravity-wave driven temperature and vertical wind perturbations only slightly modify the H2O concentrations needed to grow the crystals. We find that it would not be possible to grow the large crystals with water concentrations less than 2 ppmv, even with assumptions of a very high aspect ratio of 15 and steady upward motion of 2 cm/s to loft the crystals in the tropopause region. These calculations would seem to imply that the measurements indicating water vapor concentrations less than 2ppmv are implausible, but we cannot rule out the possibility that higher humidity prevailed upstream of the aircraft measurements and the air was dehydrated by the cloud formation. Simulations of the cloud formation with a detailed model indicate that homogeneous freezing should generate ice concentrations larger than the observed concentrations (20/L), and even concentrations as low as 20/L should have depleted the vapor in excess of saturation and prevented growth of large crystals. It seems likely that the large crystals resulted from ice nucleation on effective heterogeneous nuclei at low ice supersaturations. Improvements in our understanding of detailed cloud microphysical processes require resolution of the water vapor measurement discrepancies in these very cold, dry regions of the atmosphere.

Jensen, E. J.↗
NASA NTRS1969

Battery charge-discharge controller

Charge-discharge controller contains punched-tape programmer capable of programming 305 discrete steps in the battery load. The indicating instrumentation includes meters for ampere-hours, watt-hours, voltage, current, and internal temperature and pressure. It also generates analog signals for recording the displayed data.

Ciccanti, A. D.↗
NASA NTRS1976

Investigation of TC-1 flight failure using power spectral analysis

During the Titan Centaur 1 test flight a failure involving at least one of the Centaur propellant boost pumps occurred. Also, neither of the boost pump speed instruments indicated pump rotation. Accelerometer data from the Titan Centaur 1 flight failure were analyzed using power spectral density methods to determine boost pump speed during attempted starts of the Centaur. The technique was demonstrated on a reference flight. The hydrogen boost pump speed transient was determined for the TC-1 flight. Other trends are seen in the data. However, these are not believed to be the oxygen boost pump. Discussion of data enhancement techniques is also presented.

Lorenzo, C. F.↗
NASA NTRS1976

Cooled infrared telescope development

The feasibility of the design concept for a 1-m-aperture, cryogenically cooled telescope for Spacelab is assessed. The device makes use of double-folded Gregorian reflective optics. The planned cryogen is helium, and beryllium will be used for the 1.2 m primary mirror. Results of studies based on smaller instruments indicate that no new technology will be required to construct a Shuttle Infrared Telescope Facility which will offer improvement over the sensitivity of conventional telescopes by a factor of 1000 at 10 micrometers.

Young, L. S.↗
NASA NTRS1979

"Blind" position indicator

Position-indicating instrument helps operator align parts without seeing them. Device is useful in industrial operations where parts must be blind-positioned accurately.

Cruzan, R. C.↗
NASA NTRS1982

Space Shuttle autoland design

The Orbiter Autoland system is activated at 10,000 ft altitude and performs energy control through speedbrake modulation, vertical path tracking with acceleration commands to the pitch control system, lateral path tracking through bank angle commands to the roll control system, and brings the vehicle to main gear touchdown. A nominal 19 degree glide slope is flown down to 2000 ft, followed by a 1.5 deg path to flare and subsequent soft landing. The flight path is similar to that which a pilot would fly, a feature which increases safety factors should manual takeover be necessary during landing maneuvers. A block diagram of the autoland control interfaces is provided, and attention is given to the use of a reference trajectory, the guidance laws, lateral guidance, the speed control system, pitch rate control, and the rollout system. Conditions and instrument indications leading to pilot takeover are outlined.

Tsikalas, G. M.↗
NASA NTRS1982

Solar flare energetics

A review is presented regarding the current knowledge of the energetics of solar flares. Recent observations by the Solar Maximum Mission and by balloon-borne instrumentation indicate that the flare hard X-ray emission arises from nonthermal bremsstrahlung - the collisions of fast electrons into a cold ambient medium (Ee much greater than kT). Under this interpretation, most of the energy released for many flares is initially contained in the energetic electrons. These electrons can produce most of the observed flare phenomena via interactions with the solar atmosphere. In large flares a shock wave may result from explosive heating of the solar atmosphere by these electrons. This shock wave can accelerate nuclei to relativistic energies. It is argued that recent SMM observations of fast gamma-ray bursts are consistent with this picture of shock acceleration of nuclei.

Lin, R. P.↗
NASA NTRS1983

Observational evidence for solar wind acceleration at the base of coronal holes

An EUV spectrometer with a microchannel plate detector was developed to measure Doppler shifts of coronal and transition region lines. The results of three sounding rocket fights of this instrument indicate that EUV resonance emission lines are systematically shifted toward shorter wavelength within coronal holes. This "blue-shift" signature, first identified within compact low latitude holes, was also observed in a well developed polar coronal hole. The maximum measured shift within these coronal holes corresponds to a velocity relative to the remaining solar disc of 12 km/s in lambda 625 Mg X T to the approximately 10 to the 6.15 K power and 7 km /s/ in lambda 629 OV (T to the approximately 10 to the 5.4 K power). The existing data indicate that these blue-shifts are a common (and possibly universal) signature of coronal holes. These data provide important information on the acceleration of coronal plasma in open magnetic field regions, although the interpretation of observed Doppler shifts to derive a systematic mass flux is to some extent model dependent. A straightforward hypothesis is that the blueshift signature is a direct manifestation of the high speed solar wind deep within the transition region and inner corona.

Rottman, G. J.↗
NASA NTRS1987

A multispacecraft study of the injection and transport of solar energetic particles

The November 22, 1977 and December 27, 1977 solar energetic particle (SEP) events observed simultaneously by the Helios and the Voyager space probes and the ISEE 1 satellite are described. The spacecraft instruments indicated flux increases for H, He, and (for November 22) for O and Fe, with the energy range of 0.5-20 MeV per nucleon. It was found that the data can be well fitted by a model based on the spherically symmetric Fokker-Planck equation including convection, diffusion, and adiabatic deceleration, assuming that the radial interplanetary diffusion coefficient increases in proportion to the heliocentric radius to the power of 0.6 and that there is an extended particle injection at the sun. This extended injection is of crucial importance for the event of November 22, where the injection functions are strongly dependent on times associated with a soft energy spectrum.

Beeck, J.↗
NASA NTRS1988

Ordinary mode auroral kilometric radiation fine structure observed by DE 1

The fine structure observed with intense right-hand extraordinary (R-X) mode auroral kilometric radiation (AKR) has received major theoretical attention. Data from the Dynamics Explorer 1 plasma wave instrument indicate that left-hand ordinary (L-O) mode AKR possesses similar fine structure. Several theories have been proposed to explain the fine structure of the R-X mode AKR. In order to account for the L-O mode fine structure, these theories will have to be modified to produce the L-O mode directly or will have to rely on mode conversion processes from the R-X to the L-O mode.

Benson, Robert F.↗
NASA NTRS1988

The effects of fire on biogenic soil emissions of nitric oxide and nitrous oxide

Measurements of biogenic soil emissions of nitric oxide (NO) and nitrous oxide (N2O) before and after a controlled burn conducted in a chaparral ecosystem on June 22, 1987, showed significantly enhanced emissions of both gases after the burn. Mean NO emissions from heavily burned and wetted (to simulate rainfall) sites exceeded 40 ng N/sq m s, and increase of 2 to 3 compared to preburn wetted site measurements. N2O emissions from burned and wetted sites ranged from 9 to 22 ng N/sq m s. Preburn N2O emissions from these wetted sites were all below the detection level of the instrumentation, indicating a flux below 2 ng N/sq m s. The flux of NO exceeded the N2O flux from burned wetted sites by factors ranging from 2.7 to 3.4. These measurements, coupled with preburn and postburn measurements of ammonium and nitrate in the soil of this chaparral ecosystem and measurements of NO and N2O emissions obtained under controlled laboratory conditions, suggest that the postfire enhancement of NO and N2O emissions is due to production of these gases by nitrifying bacteria.

Levine, Joel S.↗
NASA NTRS1990

Two Tethered Balloon Systems

Systems take meteorological measurements for variety of research projects. Report describes work done by NASA Langley Research Center in atmospheric research using tethered balloon systems composed of commercially available equipment. Two separate tethered balloon systems described in report have payloads and configurations tailored to requirements of specific projects. Each system capable of measuring atmospheric parameter or species in situ and then telemetering this data in real time to ground station. Meteorological data and concentration of ozone typically measured. Indicates instrumented tethered balloon systems have distinct advantages over other systems for gathering data on troposphere.

Youngbluth, Otto↗
NASA NTRS1989

Morphology and compositional differentiation of the surface of comets

The spacecraft missions to Comet Halley gave us the first detailed view of a comet nucleus. What was suspected before, that the nucleus surface was heterogeneous, was confirmed. The Halley Multicolor Camera aboard Giotto recorded jet-like dust features emanating from active regions covering approximately 15 percent of the surface that were responsible for emitting most of the dust and gas. An intensity gradient across the nucleus originating at the active areas and falling off to the darker, inactive region on the night side is caused by small particles that are more easily entrained by surface winds than larger particles that tend to remain in the jets. Data from the PIA (Giotto) and PUMA (Vega 1,2) instruments indicate that the smallest dust particles are enriched with organics (CHON particles). Some of this fine dust gravitationally settles creating a thin surface layer rich in organics. Particularly strong dust jets may cause wind-blown surface structures over inactive areas, such as, leeward dust accumulation behind hills. At close heliocentric distances the fine dust may be sintered on the surface.

Huebner, W. F.↗
NASA NTRS1991

Use of satellite data to constrain the model-calculated atmospheric lifetime for N2O - Implications for other trace gases

Model calculations of the zonal-mean concentrations of N2O in the upper stratosphere are presented showing that about 80 percent of N2O is removed in the stratosphere between 30 deg N and 30 deg S. A comparison of calculated N2O values with remote data on N2O concentrations obtained from Nimbus 7 SAMS instrument indicated that the two-dimensional model of Ko and Sze (1982) may have underestimated the concentration of N2O in the tropical lower stratosphere. It is concluded that the calculated lifetimes for N2O and chlorofluorocarbon-source gases could be 30 percent shorter than previously reported values.

Ko, Malcolm K. W.↗
NASA NTRS1992

A case of type I polar stratospheric cloud formation by heterogeneous nucleation

The NASA ER-2 aircraft flew on January 24, 1989, from Stavanger to Spitsbergen, Norway, at the 430-440 K potential temperature surface (19.2-19.8 km pressure altitude). Aerosols were sampled continuously by an optical particle counter (PMS-FSSP300) for concentration and size analyses, and during five 10-min intervals by four wire and one replicator impactor for concentration, size, composition, and phase analysis. During sampling, the air saturation of H2O with respect to ice changed from 20 to 100 percent, and of HNO3 with respect to nitric acid trihydrate (NAT) from subsaturation to supersaturation. Data from both instruments indicate a condensation of hydrochloric acid and, later, nitric acid on the background aerosol particles as the ambient temperature decreases along the flight track. This heterogeneous nucleation mechanism generates type I polar stratospheric cloud particles of 10-fold enhanced optical depth, which could play a role in stratospheric ozone depletion.

Pueschel, R. F.↗
NASA NTRS1986

Practical design of magnetic heading sensors

Although fluxgate magnetometers have been in use for many years, and a number of theoretical studies of these sensors are available, very little information has been published on the engineering choices relating to the detailed design of magnetometers intended for navigational applications in aircraft and other vehicles. This paper addresses some of the problems encountered in the design of the sensing head, the choice of operating mode, and the design of the supporting electronics for a simple low-cost magnetometer system which will produce a digital readout of the magnetic heading of the vehicle in which it is mounted. A major goal of this study has been to develop a design which minimizes circuit complexity, is easy to fabricate and calibrate, and utilizes a minimum of specialized components. Such a magnetometer system is intended either as a stand-alone indicating instrument or as a source of magnetic heading information for a more sophisticated navigational system.

Garner, H. D.↗
NASA NTRS1994

Counting particles emitted by stratospheric aircraft and measuring size of particles emitted by stratospheric aircraft

The ER-2 condensation nuclei counter (CNC) has been modified to reduce the diffusive losses of particles within the instrument. These changes have been successful in improving the counting efficiency of small particles at low pressures. Two techniques for measuring the size distributions of particles with diameters less than 0.17 micrometers have been evaluated. Both of these methods, the differential mobility analyzer (DMA) and the diffusion battery, have fundamental problems that limit their usefulness for stratospheric applications. We cannot recommend either for this application. Newly developed, alternative methods for measuring small particles include inertial separation with a low-loss critical orifice and thin-plate impactor device. This technique is now used to collect particles in the multisample aerosol collector housed in the ER-2 CNC-2, and shows some promise for particle size measurements when coupled with a CNC as a counting device. The modified focused-cavity aerosol spectrometer (FCAS) can determine the size distribution of particles with ambient diameters as small as about 0.07 micrometers. Data from this instrument indicates the presence of a nuclei mode when CNC-2 indicates high concentrations of particles, but cannot resolve important parameters of the distribution.

Wilson, James Charles↗