Results for “Solar radio radiation” — Page 14

NASA NTRS1984

Detection of a radio emission at 3 kHz in the outer heliosphere

A radio source in the outer heliosphere has been detected by the plasma wave receivers on Voyagers 1 and 2. The radio emission is observed in the frequency range 2-3 kHz, and is above the local solar wind electron plasma frequency whenever supporting plasma density data are available. The maximum spectral density of the emission recorded is about 10 to the -14th V-squared/m-squared/Hz. The bandwidth of the radio noise is about 1 kHz. Possible sources include continuum radiation from Jupiter's distant magnetotail and radiation at the second harmonic of the plasma frequency at the heliopause. If the latter interpretation is correct, these data represent the first remote observations of the heliopause.

Kurth, W. S.↗

NASA NTRS1990

Measurement of solar magnetic fields from radio observations

Measurements of magnetic fields in the sun's atmosphere using radio observations are discussed. Radio measurements of magnetic fields in the chromosphere and the corona are indirect. In the chromosphere, these are based upon the measurement of polarization of active regions at millimeter wavelengths. In the transition region and the corona, the properties of gyroresonance radiation of active regions at centimeter wavelengths are used. Total intensity and polarization maps and modeling are used to determine which harmonic (second or third) is predominant in the active region emission. A direct method of measuring coronal magnetic fields using cyclotron line emission is discussed, and the relevant data as presently available are presented.

Kundu, M. R.↗

NASA NTRS1974

The earth as a radio source: The non-thermal continuum

A weak nonthermal continuum, radiated by the earth from energetic electrons in the outer radiation zone, is studied. It is shown that the frequency spectrum of the continuum radiation consists of two components, a trapped component, which is permanently trapped within the magnetosphere at frequencies below the solar wind plasma frequency, and an escaping component which propagates freely away from the earth at frequencies above the solar wind plasma frequency. Direction finding measurements and measurements of the spatial distribution of intensity for both components indicated that the continuum radiation is generated (1) in a broad region which extends through the morning and early afternoon immediately beyond the plasmapause boundary, and (2) over a broad range of latitudes, including the magnetic equator. Possible mechanisms by which this radiation is generated, including gyro-synchrotron radiation from energetic electrons in the outer radiation zone, are discussed.

Gurnett, D. A.↗

NASA NTRS1982

High-energy observations of stellar flares - Comparison with the sun

This paper reviews recent observations of flaring activity on flare stars of the UV Ceti type, concentrating on X-ray and radio data in comparison with possible solar analogs. Although detailed differences exist, it is concluded that similar mechanisms may work for both cases. Extending the analogy, the hard X-ray and gamma ray fluxes expected from typical stellar flares are estimated. In the solar case, these radiations give information about accelerated particles in the flare region. Hard X-ray observations of stellar flares may be possible, eventually, but the predicted gamma-ray fluxes are prohibitively weak.

Hudson, H. S.↗

NASA NTRS1983

Decimetric gyrosynchrotron emission during a solar flare

A decimetric, microwave, and hard X-ray burst was observed during a solar flare in which the radio spectrum below peak flux fits an f+2 power law over more than a decade in frequency. The spectrum is interpreted to mean that the radio emission originated in a homogeneous, thermal, gyrosynchrotron source. This is the first time that gyrosynchrotron radiation has been identified at such low decimetric frequencies (900-998) MHz). The radio emission was cotemporal with the largest single hard X-ray spike burst ever reported. The spectrum of the hard X-ray burst can be well represented by a thermal bremsstrahlung function over the energy range from 30 to 463 keV at the time of maximum flux. The temporal coincidence and thermal form of both the X-ray and radio spectra suggest a common source electron distribution. The unusual low-frequency extent of the single-temperature thermal radio spectrum and its association with the hard X-ray burst imply that the source had an area approx. 10(18) sq cm a temperature approx 5x10(8) K, an electron density approx. 7.10(9) cu cm and a magnetic field of approx. 120 G. H(alpha) and 400-800 MHz evidence suggest that a loop structure of length 10,000 km existed in the flare active region which could have been the common, thermal source of the observed impulsive emissions.

Batchelor, D. A.↗

NASA NTRS1993

The magnetic field in the corona above sunspots at the eclipse of 1991 July 11

A partial solar eclipse and an X-ray image are used to study the magnetic field as a function of height in the corona above an active region during the solar eclipse of July 11, 1991. The dominant features of AR 6718 are two leading spots of positive polarity followed by two spots of negative polarity about 3 arcmin to the east. Bright radio emission coincides with the positions of the sunspots, attributable to a gyroresonance radiation from ambient electrons above the spots. A simplified model of the source as a function of frequency based on the interferometer fringe amplitudes is used to obtain brightness temperature spectra for the emission associated with the sunspots. It is deduced that the magnetic field strength at the base of the corona above the leading spots was 1200 G, and about 1100 G above the following spots. The soft X-ray brightness above the sunspots was very low, about 30 times lower than that of the adjacent plage-associated emission.

Gary, D. E.↗

NASA NTRS1985

Remote sensing technologies for Space Missions in the second half of the nineties' decade

The remote sensing research and technology to be used in the development of future NASA missions are discussed, with consideration given to earth sciences, planetary sciences, solar physics, and astrophysics. The remote sensing missions planned in the four application areas, their payload packages, and the particular instruments that will make up these packages are described. The advanced technologies to be used include systems and devices that address the detection of radiation in the radio, microwave, millimeter wave, submillimeter wave, IR, visible, UV, X-ray, and gamma-ray parts of the spectrum, including supporting technologies, such as optics, liquid cryogen transfer systems, and 'smart' sensors.

Sokoloski, M. M.↗

NASA NTRS1960

Preliminary Results from the Space Probe Pioneer V

The space probe Pioneer V was launched March 11, 1960, into an orbit around the sun and inside the orbit of earth. The scientific apparatus included instruments identical with the University of Chicago apparatus used on Explorer VI [Fan, Meyer, and Simpson, 1960b], namely, energetic particle detectors which measure fluxes of protons with energies greater than 75 Mev, electrons with energies greater than 15 Mev, and the bremsstrahlung from electrons and y rays of lower energy. Simultaneously with the measurements in Pioneer V a series of four neutron monitor piles were recording the changes in cosmic radiation intensity at the earth. We report here on some preliminary results obtained from the Chicago experiments during the time within which Pioneer V traveled to a distance of approximately 8 x 10 km from earth. Beginning on March 20, solar activity rapidly increased with many solar flares, radio noise bursts, etc., over a period of 10 days. Most of our results relate to this period. The preliminary data are given in Figures 1 and 2.

Fan, C. Y.↗

NASA NTRS1980

The position and polarization of Type V solar bursts

Observations of the position and polarization of Type V solar radio bursts and their preceding Type III bursts are presented. The polarization, frequency range, source position, source movement, source size and brightness temperature of the bursts were measured using a 24-220 MHz spectropolarimeter, an 8-8000 MHz spectrograph and a three-frequency radioheliograph. Type V radiation is frequently found to have the opposite sense of circular polarization from that of the preceding Type III burst, with a degree of polarization similar to that of harmonic Type III radiation. A reversal of polarization is not observed when the accompanying Type III burst has no fundamental-harmonic structure, or when the Type V radiation is poorly developed. Possible mechanisms for the reversal are examined, including opposite magnetic field directions in Type III and V bursts, changes in mode coupling and a change in the mode of emission from o-mode for Type III to x-mode for Type V, and conditions needed for the mode change which is considered the most likely mechanism, are determined.

Dulk, G. A.↗

NASA NTRS1979

A theory of solar type III radio bursts

A theory of type III bursts is reviewed. Energetic electrons propagating through the interplanetary medium are shown to excite the one dimensional oscillating two stream instability (OTSI). The OTSI is in turn stabilized by anomalous resistivity which completes the transfer of long wavelength Langmuir waves to short wavelengths, out of resonance with the electrons. The theory explains the small energy losses suffered by the electrons in propagating to 1 AU, the predominance of second harmonic radiation, and the observed correlation between radio and electron fluxes.

Goldstein, M. L.↗

NASA NTRS1985

A new luminosity component in 3C 48

The infrared emission from the quasar 3C48 has a luminosity L approximately 5 x 10 to the 12th power solar luminosity and dominates the power output of the quasar system. It is shown that the infrared emission, unlike that of most radio loud quasars, is most likely not an extension of the radio emission of the quasar. It is argued that the infrared emission in 3C48 is probably thermal radiation arising in a highly luminous galaxy surrounding the quasar.

Neugebauer, G.↗

NASA NTRS1985

An attempt to detect mass loss from Alpha Lyrae with the VLA

The interpretation of the infrared excess from Alpha Lyrae as seen by the Infrared Astronomy Satellite in terms of thermal emission from a circumstellar shell of large particles follows from the recognition that small dust grains would be removed from the vicinity of the star by radiation pressure and Poynting-Robertson drag. However, this explanation is viable only if there is no resupply of small grains via mass loss from Alpha Lyr itself. Radio-continuum observations were used to constrain the stellar mass loss to less than 3.4 x 10 to the -10th solar mass/yr. The observations thus support the conclusion that the infrared excess is due to residual solid matter from the prestellar nebula.

Hollis, J. M.↗

NASA NTRS1989

Correlation studies between solar wind parameters and the decimetric radio emission from Jupiter

Results of a study comparing long-term time variations in Jupiter's synchrotron radio emission with a variety of solar wind parameters and the 10.7 cm solar flux are reported. Data from 1963 through 1985 were analyzed, and the results suggest that many solar wind parameters are correlated with the intensity of the synchrotron emission produced by the relativistic electrons in the Jovian Van Allen radiation belts. Significant nonzero correlation coefficients appear to be associated with solar wind ion density, ram pressure, thermal pressure, flow velocity, momentum, and ion temperature. The implication of these results is that the solar wind is influencing the supply and/or loss of electrons to Jupiter's inner magnetosphere.

Bolton, S. J.↗

NASA NTRS1994

Constraints on molecular gas in cooling flows and powerful radio galaxies

We searched for molecular gas in a heterogeneous sample of five radio-loud galaxies (three of which are inferred to be in cooling flow clusters) using the Swedish-European Southern Observatory (Swedish-ESO) Submillimeter Telescope. We do not detect CO in emission in any of the cluster sources at a 3 sigma level of typically 15 mK. White et al. (1991) have suggested column densities of N(sub H) approximately 10(exp 21)/sq cm in these clusters with a spatial covering factor of order unity and a total mass of M approximately 10(exp 12) solar mass. Our limits are inconsistent with these column densities and spatial covering factor unless the molecular gas is very cold (kinetic temperature close to 2.7 K) or there only a few clouds along each line of sight. We estimate minimum temperatures in the range approximately 20-30 K. We find that clouds of atomic and molecular hydrogen require strict fine-tuning of parameter space in order to satisfy the requirements for the large column densities N(sub H) approximately 10(exp 21)/sq cm, unit covering factor, and a small number of clouds along the line of sight. Currently the only way molecular gas can be responsible for the X-ray absorption and still be consistent with our observations is if (1) there is of order one cloud along the line of sight and (2) the optical depth in C-12 1 to 0 is less than 10. In addition, we present a Very Large Array (VLA) image of NGC 4696 which suggests this object is a member of the class of 'amorphous cooling flow radio sources.' The C-12 1 to 0 line is detected in emission in PKS 0634-206, a classical double radio galaxy which is rich in extended optical emission line gas. The estimated molecular gas mass is M(sub mol) approximately 3 x 10(exp 9) solar mass and is much larger than that of the ionized component detected in hydrogen alpha suggesting that the emission-line nebula is radiation bounded.

O'Dea, Christopher P.↗

NASA NTRS2023

Development of Two High-Energy Bus ‘Cores’ for Rapid Support of Low-TRL and Educational Payloads: A Software-Configured EPS Combined with Flexible C&DH

For several years the TechEdSat flight series (TES-n), developed by the Nano Orbital Workshop (NOW) group at NASA Ames, has relied upon an in-house developed unit to serve both EPS (Electrical Power System) and C&DH (Command and Data Handling) roles along with low data-rate telemetry functions, i.e., serving as the ‘core’ of the spacecraft bus. This ‘core’ has a considerable task given the rapid cadence of the TES program and the typically low-TRL of payloads; configurability and compatibility are key to prevent mission-specific hardware. However, at only 15 watts the current core has become insufficient to support the program’s growing missions and increasingly demanding payloads. To this end, the NOW program is developing new cores to support two TES mission classes: a single-PCB ‘MiniCore’ designed to support 80-watt missions 6U or smaller in LEO, and a three-PCB, radiation-tolerant ‘StackCore’ designed to support 6U and larger missions over 500 watts in LEO and beyond. The ‘MiniCore’ design consists of three main segments: a processor-agnostic C&DH, a software-configured EPS, and a backup low data-rate radio. The design philosophy was to enable rapid-manufacture in a turbulent supply chain, hence the design consists of COTS parts with a focus on those able to be drop-in replaced with radiation-tolerant versions when demanded by the mission. As a single PC-104 sized circuit board, power density and ease of integration also dominated design, demanding the use of modern features such as single-point USB-C for easy charging and monitoring of the spacecraft on the ground. The ‘MiniCore’ can support 80 watts of load, 140 watt-hours of storage, and over 20 watts of optimized solar generation with extensive power monitoring throughout. The ‘MiniCore’ supports one battery pack, six solar-panels, six loads, five actuators, Iridium SBD, and an internal 802.15.4 network. Additionally, the processor-agnostic design can accept any PJRC Teensy 3.x or Adafruit Feather microcontroller unit to enable processor scaling with mission requirements or environment. It is expected a development unit of this design will be completed before conference. The ‘StackCore’ design consists of three stacked PC-104 sized circuit boards: one dedicated to power generation and storage, one dedicated to power distribution, and one dedicated to C&DH tasks. This delineation is necessary to support the transition from highly integrated ICs to discrete analog circuitry, enabling a primarily analog control power system able to operate without software in a radiation environment with finer monitoring compared to the ‘MiniCore’ design. The planned base architecture supports over 500 watts of load, 250 watt-hours of storage, and over 80 watts of optimized solar generation. The power distribution board allows for the use of daughter cards hosting custom converters or interfaces for payloads, in addition to the software-configured supplies used on the ‘MiniCore’. This core stack will be managed by a Vorago ARM M4 microcontroller and support the same wireless communications as the ‘MiniCore’, with optional integration of a NOW S-band radio and attitude determination sensors for ‘black box’ functionality. It is expected the prototype will still be in development during conference.

Spacecraft↗

NASA NTRSDate not supplied

Development of Two High-Energy Bus ‘Cores’ for Rapid Support of Low-TRL and Educational Payloads: A Software-Configured EPS Combined with Flexible C&DH

For several years the TechEdSat flight series (TES-n), developed by the Nano Orbital Workshop (NOW) group at NASA Ames, has relied upon an in-house developed unit to serve both EPS (Electrical Power System) and C&DH (Command and Data Handling) roles along with low data-rate telemetry functions, i.e., serving as the ‘core’ of the spacecraft bus. This ‘core’ has a considerable task given the rapid cadence of the TES program and the typically low-TRL of payloads; configurability and compatibility are key to prevent mission-specific hardware. However, at only 15 watts the current core has become insufficient to support the program’s growing missions and increasingly demanding payloads. To this end, the NOW program is developing new cores to support two TES mission classes: a single-PCB ‘MiniCore’ designed to support 80-watt missions 6U or smaller in LEO, and a three-PCB, radiation-tolerant ‘StackCore’ designed to support 6U and larger missions over 500 watts in LEO and beyond. The ‘MiniCore’ design consists of three main segments: a processor-agnostic C&DH, a software-configured EPS, and a backup low data-rate radio. The design philosophy was to enable rapid-manufacture in a turbulent supply chain, hence the design consists of COTS parts with a focus on those able to be drop-in replaced with radiation-tolerant versions when demanded by the mission. As a single PC-104 sized circuit board, power density and ease of integration also dominated design, demanding the use of modern features such as single-point USB-C for easy charging and monitoring of the spacecraft on the ground. The ‘MiniCore’ can support 80 watts of load, 140 watt-hours of storage, and over 20 watts of optimized solar generation with extensive power monitoring throughout. The ‘MiniCore’ supports one battery pack, six solar-panels, six loads, five actuators, Iridium SBD, and an internal 802.15.4 network. Additionally, the processor-agnostic design can accept any PJRC Teensy 3.x or Adafruit Feather microcontroller unit to enable processor scaling with mission requirements or environment. It is expected a development unit of this design will be completed before conference. The ‘StackCore’ design consists of three stacked PC-104 sized circuit boards: one dedicated to power generation and storage, one dedicated to power distribution, and one dedicated to C&DH tasks. This delineation is necessary to support the transition from highly integrated ICs to discrete analog circuitry, enabling a primarily analog control power system able to operate without software in a radiation environment with finer monitoring compared to the ‘MiniCore’ design. The planned base architecture supports over 500 watts of load, 250 watt-hours of storage, and over 80 watts of optimized solar generation. The power distribution board allows for the use of daughter cards hosting custom converters or interfaces for payloads, in addition to the software-configured supplies used on the ‘MiniCore’. This core stack will be managed by a Vorago ARM M4 microcontroller and support the same wireless communications as the ‘MiniCore’, with optional integration of a NOW S-band radio and attitude determination sensors for ‘black box’ functionality. It is expected the prototype will still be in development during conference.

Spacecraft↗

NASA NTRSDate not supplied

Development of Two High-Energy Bus ‘Cores’

For several years the TechEdSat flight series (TES-n), developed by the Nano Orbital Workshop (NOW) group at NASA Ames, has relied upon an in-house developed unit to serve both EPS (Electrical Power System) and C&DH (Command and Data Handling) roles along with low data-rate telemetry functions, i.e., serving as the ‘core’ of the spacecraft bus. This ‘core’ has a considerable task given the rapid cadence of the TES program and the typically low-TRL of payloads; configurability and compatibility are key to prevent mission-specific hardware. However, at only 15 watts the current core has become insufficient to support the program’s growing missions and increasingly demanding payloads. To this end, the NOW program is developing new cores to support two TES mission classes: a single-PCB ‘MiniCore’ designed to support 80-watt missions 6U or smaller in LEO, and a three-PCB, radiation-tolerant ‘StackCore’ designed to support 6U and larger missions over 500 watts in LEO and beyond. The ‘MiniCore’ design consists of three main segments: a processor-agnostic C&DH, a software-configured EPS, and a backup low data-rate radio. The design philosophy was to enable rapid-manufacture in a turbulent supply chain, hence the design consists of COTS parts with a focus on those able to be drop-in replaced with radiation-tolerant versions when demanded by the mission. As a single PC-104 sized circuit board, power density and ease of integration also dominated design, demanding the use of modern features such as single-point USB-C for easy charging and monitoring of the spacecraft on the ground. The ‘MiniCore’ can support 80 watts of load, 140 watt-hours of storage, and over 20 watts of optimized solar generation with extensive power monitoring throughout. The ‘MiniCore’ supports one battery pack, six solar-panels, six loads, five actuators, Iridium SBD, and an internal 802.15.4 network. Additionally, the processor-agnostic design can accept any PJRC Teensy 3.x or Adafruit Feather microcontroller unit to enable processor scaling with mission requirements or environment. It is expected a development unit of this design will be completed before conference. The ‘StackCore’ design consists of three stacked PC-104 sized circuit boards: one dedicated to power generation and storage, one dedicated to power distribution, and one dedicated to C&DH tasks. This delineation is necessary to support the transition from highly integrated ICs to discrete analog circuitry, enabling a primarily analog control power system able to operate without software in a radiation environment with finer monitoring compared to the ‘MiniCore’ design. The planned base architecture supports over 500 watts of load, 250 watt-hours of storage, and over 80 watts of optimized solar generation. The power distribution board allows for the use of daughter cards hosting custom converters or interfaces for payloads, in addition to the software-configured supplies used on the ‘MiniCore’. This core stack will be managed by a Vorago ARM M4 microcontroller and support the same wireless communications as the ‘MiniCore’, with optional integration of a NOW S-band radio and attitude determination sensors for ‘black box’ functionality. It is expected the prototype will still be in development during conference.

Avery Brock↗

NASA NTRS1985

Cometary kilometric radio waves and plasma waves correlated with ion pick-up effect at Comet Halley

Bow-shock movements at Comet Halley are inferred from the discrete spectra of the cometary kilometric radiation (30-195 kHz); the observed emissions can be interpreted as being generated and propagating from the moving shock. The shock motion is possibly associated with the time variation of the solar wind and cometary outgassing. It is concluded that these plasma wave phenomena are manifestations of ion pick-up processes, which occur even in a remote region 7 million to 10 million km from the cometary nucleus.

Oya, H.↗