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NASA NTRS2011

Why Atens Enjoy Enhanced Accessibility For Human Space Flight

In the context of human space flight (HSF), the concept of near-Earth object (NEO) accessibility is highly subjective. Whether or not a particular NEO is accessible critically depends on mass, performance, and reliability of interplanetary HSF systems yet to be designed. Such systems would certainly include propulsion and crew life support with adequate shielding from both solar flares and galactic cosmic radiation. Equally critical architecture options are relevant to NEO accessibility. These options are also far from being determined and include the number of launches supporting an HSF mission, together with whether or not consumables are to be pre-emplaced at the destination. Until the unknowns of HSF to NEOs come into clearer focus, the notion of relative accessibility is of great utility. Imagine a group of NEOs, each with nearly equal HSF merit determined from their individual characteristics relating to crew safety, scientific return, resource utilization, and planetary defense. The more accessible members of this group are more likely to be explored first. A highly accessible NEO could conceivably be deferred in favor of a less accessible HSF destination because the latter is more accessible during a programmatically desirable launch compliant mission trajectory solutions detected in association with a specific NEO. The known NEO population is then surveyed to illustrate in which regions of heliocentric semi-major axis, eccentricity, and inclination (a, e, i) space NEOs with large n values are mapped. The (a, e, i) mapping is also formatted such that membership in each of four NEO orbit classifications, as defined below, is evident. Amors have orbits everywhere superior to (outside of) Earth's. An Amor is therefore defined to have perihelion between 1.017 astronomical units (AU) and the maximum NEO value of 1.3 AU. As of 0 hrs Universal Time on 1 January 2011 (UT epoch 2011.0), Amors numbered 2855 in the Jet Propulsion Laboratory (JPL) Small-Body Database (SBDB), comprising 37.7% of known NEOs. Apollos have orbits crossing Earth's with periods greater than Earth's. An Apollo is therefore defined to have perihelion less than 1.017 AU and a greater than 1.0 AU. As of 2011.0 UT, Apollos numbered 4080 in the SBDB, comprising 53.9% of known NEOs. Atens have orbits crossing Earth's with periods less than Earth's. An Aten is therefore defined to have aphelion greater than 0.983 AU and a less than 1.0 AU. As of 2011.0 UT, Atens numbered 618 in the SBDB, comprising 8.2% of known NEOs. Atiras have orbits everywhere inferior to (inside of) Earth's. An Atira is therefore defined to have aphelion less than 0.983 AU. As of 2011.0 UT, Atiras numbered 11 in the SBDB, comprising 0.1% of known NEOs. It is no surprise that the largest n values are chiefly associated with Apollos and Atens. Because these orbits cross Earth's, distance to be covered in a given round trip mission time delta-t can be far less than is possible for Amors or Atiras . This delta-t or the sum of mission propulsive impulse magnitudes delta-v can more frequently be minimized to enhance NHATS compliance for Apollos and Atens than is generally the case for Amors and Atiras. A less intuitive trend in NHATS results is that Atens nearly outnumber the more numerous Apollos among the most compliant NEOs as measured by n. This trend is completely out of proportion to the degree Atens are represented among the known NEO population. A theory based on geocentric NEO dynamics is presented by this paper to explain why Atens enjoy inherently greater accessibility than do Apollos. Another trend evident from mapping into (a, e, i) space is the dearth of known NEOs at low e when a < 1 AU. Underrepresentation of Atens and Atiras in the NEO catalog is at least in part attributable to observing exclusively from a perspective near Earth. Generally inferior Aten and Atira orbits are rarely, if ever, in Earth's night sky. Until a comprehensive NEO survey is conducted from an appropriateegion remote from Earth, the theory developed in this paper indicates a substantial fraction of the most accessible NEOs will remain unknown. season. Such a season is really yet another undetermined HSF architecture option. A launch season's duration will likely be measured in weeks, and it will be utilized at an indeterminate point almost certainly more than a decade in the future when HSF programmatic maturity is sufficient. Furthermore, current knowledge of the NEO population relevant to HSF is far from complete. In the 100-m-diameter class of greatest interest, only a few percent of the estimated NEO population is known [2, Figure 2.4]. Therefore, any known, lost, or fictitious NEO in a highly accessible orbit is a potential HSF destination of merit. Even if lost, fictitious, small, or hazardous, such a potential target (or another in a similar orbit) may ultimately prove to be an early HSF destination when the pertinent NEO population is more thoroughly catalogued and NEO orbits are more thoroughly maintained at high accuracy. This paper first reviews methodology and pertinent results from NASA-sponsored research performed in late 2010 and dubbed NEO HSF Accessible Targets Study (NHATS, pronounced as "gnats"). A useful accessibility metric developed during this study is n, the tally of NHATS-

Barbee, Brent↗
NASA NTRS2017

Detection and Interpretation of Long-lived X-Ray Quasi-Periodic Pulsations in the X-Class Solar Flare on 2013 May 14

Quasi-periodic pulsations (QPP) seen in the time derivative of the GOES soft X-ray light curves are analyzed for the X3.2 event on 2013 May 14. The pulsations are apparent for a total of at least two hours from the impulsive phase to well into the decay phase, with a total of 163 distinct pulses evident to the naked eye. A wavelet analysis shows that the characteristic timescale of these pulsations increases systematically from approx. 25 s at 01:10 UT, the time of the GOES peak, to approx. 100 s at 02:00 UT. A second ridge in the wavelet power spectrum, most likely associated with flaring emission from a different active region, shows an increase from approx. 40 s at 01:40 UT to approx. 100 s at 03:10 UT. We assume that the QPP that produced the first ridge result from vertical kink-mode oscillations of the newly formed loops following magnetic reconnection in the coronal current sheet. This allows us to estimate the magnetic field strength as a function of altitude given the density, loop length, and QPP timescale as functions of time determined from the GOES light curves and Ramaty High Energy Solar Spectroscopic Imager (RHESSI) images. The calculated magnetic field strength of the newly formed loops ranges from approx. 500 G at an altitude of 24Mm to a low value of approx. 10 G at 60 Mm, in general agreement with the expected values at these altitudes. Fast sausage-mode oscillations are also discussed and cannot be ruled out as an alternate mechanism for producing the QPP.

Dennis, Brian R.↗
NASA NTRS2018

Nitrogen Oxides in the Global Upper Troposphere: Interpreting Cloud-Sliced NO2 Observations from the OMI Satellite Instrument

Nitrogen oxides (NOx≡NO+NO2) in the upper troposphere (UT) have a large impact on global tropospheric ozone and OH (the main atmospheric oxidant). New cloud-sliced observations of UT NO2 at 450–280 hPa (∼6–9 km) from the Ozone Monitoring Instrument (OMI) produced by NASA and the Royal Netherlands Meteorological Institute (KNMI) provide global coverage to test our understanding of the factors controlling UT NOx. We find that these products offer useful information when averaged over coarse scales (20°×32°, seasonal), and that the NASA product is more consistent with aircraft observations of UT NO2. Correlation with Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) satellite observations of lightning flash frequencies suggests that lightning is the dominant source of NOx to the upper troposphere except for extratropical latitudes in winter. The NO2 background in the absence of lightning is 10–20 pptv. We infer a global mean NOx yield of 280±80 moles per lightning flash, with no significant difference between the tropics and midlatitudes, and a global lightning NOx source of 5.9±1.7 Tg N a(exp −1). There is indication that the NOx yield per flash increases with lightning flash footprint and with flash energy.

Marais, Eloise A.↗
NASA NTRSDate not supplied

In-Situ Detection of Process-Induced Porosity During Cure of Out-of-Autoclave Composites

Composite materials offer unique benefits in aerospace applications, including high strength-to-weight ratio, and are becoming increasingly used by industry manufacturers. Current manufacturing and processing methods can lead to defects in the composites, which are identified after fabrication using inspection methods. This study utilized a high-temperature ultrasonic inspection system to detect process-induced porosity in an out-of-autoclave (OOA) composite panel during cure. In order to perform ultrasonic scans in-situ during cure, the system needed to be able to operate at oven temperatures up to 200 °C. There are no commercially available ultrasonic scanning systems that can operate continuously at these temperatures, so an enclosure was fabricated to insulate the ultrasonic system in the curing oven. The enclosure housed a MISTRAS® motorized X-Y raster scanner and contact transducer (Olympus® X2002). The Olympus® X2002 contact transducer is a continuous high-temperature delay line transducer with a center frequency of 2.25 MHz. In order to prevent the inside of the enclosure from reaching high temperatures, a sparge pipe inside the cooling enclosure was connected to a liquid nitrogen (LN2) tank outside of the oven via insulated hoses. The cooling system was automatically controlled by a temperature controller that was programmed to open a solenoid valve along the hose at 31 ℃ and close at 28 ℃ inside the cooling enclosure. When the solenoid valve was open, LN2 would flow from the LN2 tank and vaporize prior to reaching cooling enclosure. A U-shaped sparge pipe had holes drilled along its length to uniformly introduce cold nitrogen gas into the cooling enclosure. This prevented the motors from ever reaching the maximum desired operating temperature of 38 ℃. In the bottom of the enclosure, the tool plate was placed with the composite facing the outside of the enclosure, exposing it to the temperatures of the oven. The tool plate was 63.5 mm thick borosilicate glass, which was chosen for its low ultrasonic attenuation and moderate thermal conductivity. A thin layer of ultrasonic couplant was placed on the tool plate. The transducer sent and received ultrasonic waves through the tool plate into the composite. A MISTRAS® Remote UT System performed all wave generation, analog to digital conversion, and data acquisition and processing. The transducer was connected directly to the Remote UT System via a high-temperature BNC cable (CD International, RG-316). Polyimide insulated copper wire was used to connect the scanner to a 2-axis motor drive, which was connected to the Remote UT System. The motor drive and Remote UT System were located outside the industrial oven. A diagram of the ultrasonic system is shown in Figure 1. Figure 1: Diagram of ultrasonic in-situ defect detection system. In this study, a porosity gradient was introduced into the carbon fiber reinforced polymer (CFRP) composite through a misfit of the part and caul plate. A 24-ply quasi-isotropic ([0/90, ±45]12S) composite panel was laid up using Newport® AS4C-M/NB321 out-of-autoclave (OOA) plain weave (PW) prepreg (42% resin content, 195 g/m2). The first 16 plies were 203 mm × 203 mm. Ply drops were incorporated into the panel by decreasing the length of plies 17-24. The sizes of each ply are included in Table 1. All plies were centered along their length (x-axis) creating a trapezoidal type cross-section. Table 1: Ply sizes Plies Length (mm) Width (mm) 1-16 203 203 17-18 102 203 19-20 85 203 21-22 68 203 23-24 51 203 A 15-5 stainless steel caul plate (Size: 203 × 203 × 1.2 mm) was placed on the laminate. The composite and caul plate were vacuum bagged to the tool plate. Per the product datasheet, Newport 321 can be cured between 121 °C and 149 °C, depending on service temperature, with a hold for 90-120 minutes. Based on prior thermal testing of the cooling enclosure, the desired composite temperature cycle could be attained when the air temperature of the oven was ramped to 160 °C at a rate of 1.7 °C/min with a 3 hour hold. The extended hold was not necessary to cure the composite, but did allow for additional scans at the cure temperature during preliminary testing. The composite panel was under vacuum pressure for the entire cure cycle. Under vacuum, the caul plate deformed causing high and low pressure regions. The low-pressure regions formed high porosity in the composite part. The ultrasonic data collected showed that the inspection system was able to monitor the evolution of porosity within the composite throughout the cure cycle. Fifty scans of a 203 mm × 51 mm (8 in. × 2 in.) area of the composite were completed throughout the cure cycle. The scan speed was set to 43 mm/s in the x-direction and 36 mm/s in the y-direction, with a 1.0 mm/pixel resolution in both directions. Each scan took approximately five minutes to complete. Figure 2 shows C-scan amplitude data (top view) from one scan during the cure cycle. The color map indicates the maximum amplitude (%) measured with a time gate that contains reflections from the back surface (furthest from the transducer in contact with the caul plate) of the composite. Because porosity in the composite increases the ultrasonic attenuation in the composite part, a higher amplitude (red) indicates low porosity and a lower amplitude (blue) indicates high porosity. The regions where the caul plate was applying increased pressure (center and ends of the panel) resulted in reduced porosity, whereas the ply drop regions had reduced pressure and thus had higher porosity. Figure 2: Amplitude C-scan (top view) of OOA composite from one scan during the 160 °C temperature hold. Higher amplitude (red) indicates low porosity. Lower amplitude (blue) indicates high porosity. A B-scan is a two-dimensional image plotting the ultrasonic signals from a single y-position at every x-location of the composite panel. The travel time (μs) of the ultrasonic wave (representing the through-thickness location) is plotted along the y-axis, and the ultrasonic wave signal is represented as a contour map. Based on the B-scan data, the location of the defects with respect to the composite thickness was able to be determined. The ply drop regions had high porosity near the front (tool plate) surface of the composite (Figure 3). Figure 3: B-scan (cross-section view) of OOA composite from one scan during the 160 °C temperature hold. Using the data obtained from amplitude C-scans and B-scans throughout the cure cycle, the high and low porosity regions within the composite laminate were detected and localized with high spatial resolution. This paper will discuss the evolution of porosity content in the OOA composite during cure. OOA tests aided the transition of this system to an autoclave, which is the primary method of curing aerospace-grade thermoset composites.

Tyler B. Hudson↗
NASA NTRS2020

A Double Disturbed Lunar Plasma Wake

Under nominal solar wind conditions, a tenuous wake forms downstream of the lunar nightside. However, the lunar plasma environment undergoes a transformation as the Moon passes through the Earth's magnetotail, with hot subsonic plasma causing the wake structure to disappear. We investigate the lunar wake response during a passing coronal mass ejection (CME) on March 8, 2012 while crossing the Earth's magnetotail using both a magnetohydrodynamic (MHD) model of the terrestrial magnetosphere and a three-dimensional hybrid plasma model of the lunar wake. The CME arrives at 1 AU around 10:30 UT and its impact is first detected inside the geomagnetic tail after 11:10 UT by the Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun (THEMIS-ARTEMIS) satellites in lunar orbit. A global magnetospheric MHD simulation using Wind data for upstream conditions with the OpenGGCM model reveals the magnetosheath compression to the lunar position from 11:20–12:00 UT, accompanied by multiple flux rope or plasmoid-like features developing and propagating tailward. MHD results support plasma changes observed by the THEMIS-ARTEMIS satellites. Lunar-scale simulations using the Amitis hybrid code show a short and misaligned plasma wake during the Moon's brief entry into the magnetosheath at 11:20 UT, with plasma expansion into the void being aided by the higher plasma temperatures. Sharply accelerated flow speed and a compressed magnetic field lead to an enhanced electric field in the lunar wake capable of generating sudden changes to the nightside near-surface electric potential.

A. P. Rasca↗
NASA NTRS2007

Connecting Surface Emissions, Convective Uplifting, and Long-Range Transport of Carbon Monoxide in the Upper Troposphere: New Observations from the Aura Microwave Limb Sounder

Two years of observations of upper tropospheric (UT) carbon monoxide (CO) from the Aura Microwave Limb Sounder are analyzed; in combination with the CO surface emission climatology and data from the NCEP analyses. It is shown that spatial distribution, temporal variation and long-range transport of UT CO are closely related to the surface emissions, deep-convection and horizontal winds. Over the Asian monsoon region, surface emission of CO peaks in boreal spring due to high biomass burning in addition to anthropogenic emission. However, the UT CO peaks in summer when convection is strongest and surface emission of CO is dominated by anthropogenic source. The long-range transport of CO from Southeast Asia across the Pacific to North America, which occurs most frequently during boreal summer, is thus a clear imprint of Asian anthropogenic pollution influencing global air quality.

upper tropospheric (UT)↗
NASA NTRS1974

Pioneer Solar Plasma and Magnetic Field Measurements in Interplanetary Space During August 2-17, 1972

Solar wind plasma and magnetic field measurements from Pioneers 9 and 10 during August 2-17, 1972, reveal complex and large-amplitude variations on a one-hour time scale and numerous discontinuities. During this time period an approximate radial alignment of the two spacecraft as seen from the Sun occurred with heliocentric distances of 0.8 AU for Pioneer 9 and 2.2 AU for Pioneer 10, both at 45 deg east of the Earth's solar longitude. The peak hourly average solar wind proton bulk velocity measured at Pioneer 9 was 990 km sec (exp -1) during hour 0 UT of August 5. The peak hourly average proton number density was 62 cm (exp -3) during hour 11 UT of August 3. The peak solar wind speeds are generally much reduced at Pioneer 10 compared with those observes at Pioneer 9. The peak 30 minute average magnetic field magnitude was 85 gamma during 1245 - 1315 UT of August 3. The Pioneer 9 data indicate passage of four fast forward interplanetary shocks, and one slow forward interplanetary shock.

Mihalov, J. D.↗
NASA NTRS1979

Physical parameter analysis of an intense, compact subflare

Results of analysis of Skylab X-ray proportional counter data (10-s averages) and X-ray telescope filtergrams for the August 9, 1973 (SN/M2) subflare from McMath 12474 (NOAA AR 185) are presented. The event flux profiles and profiles of temperature, volume emission-measure, and a quantity equivalent to thermal energy content are shown. Using the proportional counter data, a peak temperature in excess of 20,000,000 K at 1552:05 UT, a peak volume emission measure of 7 x 10 to the 48th per cu cm at 1553:25 UT, and a peak value of thermal energy content of 2 x 10 to the 16th evgs/cm to the 3/2 power at 1552:45 UT were derived. Based on the analysis of spatially-resolved X-ray images during the period near flare-peak through flare-decay, the flare is observed to be both intense and compact and to consist of at least two identifiable loops whose volumes remained essentially unchanged throughout the event.

Wilson, R. M.↗
NASA NTRS1980

Spectrum synthesis of EUV solar flare line profiles

A classic double ribbon flare of importance 1B occurred at approximately 1405 UT on June 15, 1973, reached an H alpha maximum at 1413 UT, and ended at 1455 UT. The flare occurred in an old and simplifying bipolar region at N18 W32. This flare was studied due to the extensive temporal data available. A total of 136 spectra of wavelength ranges from 1100 to 3000 A were taken during the flare's duration by the Naval Research Laboratory normal incidence slit spectrograph. Using this data the nature of the solar chromosphere of a flare event as a function of time was determined.

Tripp, D. A.↗
NASA NTRS1980

Observations of the Crab Nebula, NGC 4151, Cyg X1 and Cyg X3 at medium gamma ray energies

The paper analyzes observations of the Crab Nebula, NGC 4151, Cyg X1, and Cyg X3 taken with the UCR gamma ray telescope at a residual atmospheric depth of about 3.5 g/sq cm on a balloon launched from Palestine, Texas, 4.5 GV, 2000 local time LT (0100 UT), on September 29, 1978. The data consists of continuous observations from 0430 LT (0930 UT) on September 30 to 1800 LT (2300 UT) on October 1, 1979. A flux increase is observed at the right ascension of the Crab Nebula within about a 10 min uncertainty of telescope source position determination, eliminating the SAS-2, CG 195+4, and the two COS-B sources in the antigalactic center direction as the origin of the gamma rays. The total flux of gamma rays for the Crab Nebula from 1.2 to 10 MeV is (6.1 + or - 1.5) x 10 to the -3rd photons/sq cm-s, with an upper limit at 10-20 MeV of 7 x 10 to the -5th photons/sq cm-s. Results for the NGC 4151, Cyg X1, and Cyg X3 are also discussed and flux upper limits are given.

Zanrosso, E. M.↗
NASA NTRS1982

Observation and modeling of energetic particles at synchronous orbit on July 29, 1977

In the 12 hours immediately after a worldwide storm sudden commencement at 0027 UT on July 29, there was a series of at least four magnetospheric substorms, the last and largest of which exhibited an expansion phase onset at approximately 1200 UT. Data from six spacecraft in three general local time groupings (0300, 0700, and 1300 LT) are examined, and vector magnetic field data and energetic electron and ion data from approximately 15 keV to more than 2MeV are employed. Four primary types of studies are carried out: (1) timing and morphology of energetic particle injections; (2) variation of particle phase space densities, using local magnetic field and particle flux data; (3) measurement of boundary motions, using high-energy ion gradient anisotropies; and (4) adiabatic modeling, which included injection, large-scale convection, corotation, and gradient drifts. For the 1200 UT substorms, it is concluded that there was a substantial flux dropout in a broad sector near local midnight because of a large-scale boundary motion, followed by a recovery to a predropout configuration.

Baker, D. N.↗
NASA NTRS1982

The observation of a coronal transient directed at earth

The paper reports the observation of a large coronal transient that can only be interpreted as a three-dimensional structure. Its form is one which has not been observed before: a gradually expanding, sun-centered disk of excess brightness, whose projected radius increased from 4 to 8 solar radii during 0832-0958 UT on November 27, 1979. This earth-directed transient was the source of an interplanetary shock wave that reached ISEE 3 at 0649 UT, November 30, and earth at 0738 UT, November 30. Fitting the shock speed at ISEE 3 and the average transit speed from the sun to ISEE 3 to a power law of the form V = (V sub 0)(r exp -n), it is found that V sub 0 = 1980 km/s and n = 0.294, in good agreement with shock wave models. The shock speed predicted by the power law at 10 solar radii is 1000 km/s, in good agreement with the estimated frontal speed of the transient.

Howard, R. A.↗
NASA NTRS1985

Injection of energetic particles following the gamma-ray flares on June 7, 1980, as observed on Helios 1

On June 7, 1980, two flares with impulsive gamma-ray emission were observed at 0117 Ut and 0312 UT. Measurements of the University of Kiel cosmic-ray experiment on HELIOS-1 are presented. The first approx. 0.5 MeV electrons escaped from the Sun to interplanetary space simultaneously with the hard X-ray burst. For the 0312 UT flare the protons and alpha-particle in the 3 - 20 MeV/nucleon range were injected from the Sun with a delay of approx. 40 min, followed by two subsequent new emissions.

Neustock, H. H.↗
NASA NTRS1985

Electric fields in the plasma sheet and plasma sheet boundary layer

Results obtained by Forbes et al. (1981) on the basis of time delay measurements between ISEE 1 and ISEE 2 imply that the plasma flow and the boundary contracting velocity were nearly the same, whereas the expanding boundary velocity was not accompanied by any significant plasma sheet plasma motion. In the present study, this observation is discussed in conjunction with electric field data. The study is based on electric field data from the spherical double probe experiment on ISEE 1. Electric field data from GEOS 2 are used to some extent to monitor the electric fields near the geostationary orbit during the considered eve nts. Electric field data during CDAW 6 events are discussed, taking into account positions of ISEE 1/ISEE 2 and GEOS 2; March 22, 0600-1300 UT; and March 22, UT; and March 31, 1400-2400 UT.

Pedersen, A.↗
NASA NTRS1985

Suprathermal O(+) and H(+) ion behavior during the March 22, 1979 (CDAW 6), substorms

The present investigation has the objective to report on the behavior of energetic (approximately 130 keV) O(+) ions in the earth's plasma sheet, taking into account observations by the ISEE 1 spacecraft during a magnetically active time interval encompassing two major substorms on March 22, 1979. Attention is also given to suprathermal H(+) and He(++) ions. ISEE 1 plasma sheet observations of the proton and alpha particle phase space densities as a function of energy per charge during the time interval 0933-1000 UT on March 22, 1979 are considered along with the proton phase space density versus energy in the energy interval approximately 10 to 70 keV for the selected time periods 0933-1000 UT (presubstorm) and 1230-1243 UT (recovery phase) during the 1055 substorm on March 22, 1979. A table listing the proton energy density for presubstorm and recovery periods is also provided.

Ipavich, F. M.↗
NASA NTRS1986

UT/longitudinal variations of composition in DE data

Composition data obtained by the quadrupole mass spectrometer (NACS) carried aboard the DE-B satellite were examined for variations in the polar regions during magnetically quiet conditions. The corresponding predictions of the MSIS-83 model are often used for comparison. The MSIS-83 model is used to emphasize the variations of interest by suppressing all other variations. A persistent enhancement of N2 density and a depletion of He density are present in the vicinity of the magnetic poles with maximum density response in the morning hours (magnetic) on average. A universal time (UT) variation in average density levels is evident near both the geographic and magnetic poles. There are systematic morphology changes with UT and between summer and winter which are qualitatively consistent with the simple concept that thermospheric heating effects are shifted or spread in the downwind direction of the global circulation systems driven by EUV and magnetospheric sources. The magnitude of the UT variations is larger in the southern hemisphere and is larger in local winter than summer.

Hedlin, A. E.↗
NASA NTRS1986

Compact, variable, moving sources observed on the sun at 2 centimeters wavelength

The Very Large Array (VLA) was used to observe the active region AT 4508 in the C-configuration between 1530 and 2330 UT on June 4, 1984. The position of this region was N06 E57 at 1300 UT on this day. Followup observations were made between 1500 and 2300 UT on January 17, 1986 in the D-configuration. Observations were compared with Mt. Wilson magnetograms. Results are discussed.

Lang, Kenneth R.↗
NASA NTRS1989

Middle atmosphere measurements of small-scale electron density irregularities and ion properties during the MAC/Epsilon campaign

Rocket payloads designed to measure small scale electron density irregularities and ion properties in the middle atmosphere were flown with each of the three main salvos of the MAC/Epsilon campaign conducted at the Andoya Rocket Range, Norway, during October to November 1987. Fixed bias, hemispheric nose tip probes measured small scale electron density irregularities, indicative of neutral air turbulence, during the rocket's ascent; and subsequently, parachute-borne Gerdien condensers measured the region's polar electrical conductivity, ion mobility and density. One rocket was launched during daylight (October 15, 1052:20 UT), and the other two launches occurred at night (October 21, 2134 UT: November 12, 0021:40 UT) under moderately disturbed conditions which enhanced the detection and measurement of turbulence structures. A preliminary analysis of the real time data displays indicates the presence of small scale electron density irregularities in the altitude range of 60 to 90 km. Ongoing data reduction will determine turbulence parameters and also the region's electrical properties below 90 km.

Blood, S. P.↗