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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 NTRS2022

The Sun Radio Interferometer Space Experiment (SunRISE) Mission

The Sun Radio Interferometer Space Experiment (SunRISE) will provide an entirely new view on particle acceleration and transport in the inner heliosphere by creating the first low radio frequency interferometer in space to localize heliospheric radio emissions. By imaging and determining the location of decametric-hectometric (DH, 0.1 MHz–23 MHz) solar radio bursts, SunRISE will provide key information on particle acceleration mechanisms associated with coronal mass ejections (CMEs) and the magnetic field topology from active regions into interplanetary space. The SunRISE Observatory will consist of six space vehicles in a passive formation, in orbits designed to keep them within approximately 10 km of each other, and flying in a supersynchronous geosynchronous Earth orbit (GEO). Each space vehicle consists of a Solar DH-GNSS payload and a 6U form factor spacecraft. The SunRISE Observatory together with significant ground-based processing, will enable imaging of the Sun in a portion of the spectrum that is blocked by the ionosphere and cannot be observed from Earth. Key aspects that enable this mission are that only position knowledge of the space vehicles is required, not active control, and that the architecture involves a modest amount of on-board processing coupled with significant ground-based processing for navigation, position determination, and science operations. Mission-enabling advances in software-defined radios, GPS navigation and timing, and small spacecraft technologies, developed and flown on the DARPA High Frequency Research (DHFR) and the Community Initiative for Continuing Earth Radio Occultation (CICERO) have made this mission affordable and low-risk. The SunRISE mission will exploit the multiple spacecraft per aperture (MSPA) capability of NASA’s Deep Space Network (DSN), for more efficient data transfers of larger data volumes, and utilize commercial access to space, in which the SunRISE space vehicles will be carried to their target orbit as secondary payloads in conjunction with a larger host spacecraft intended for GEO.

Neilson, Tim↗
NASA NTRS1999

Enhanced Fair-Weather Electric Fields Soon After Sunrise

The typical fair weather electric field at the ground is between -100 and -300 V/m. At the NASA Kennedy Space Center and US Air Force Cape Canaveral Air Station (KSC) the electric field at the ground sometimes reaches -400 to -1200 V/m within an hour or two after sunrise on days that otherwise seem to be fair weather. We refer to the enhanced negative electric fields as the "sunrise enhancement." To investigate the sunrise enhancement at KSC we measured the electric field (E) in the first few hundred meters above the ground before and during several sunrise enhancements. From these E soundings we can infer the presence of charge layers and determine their thickness and charge density.

Marshall, T. C.↗
NASA NTRS2021

The Sun Radio Interferometer Space Experiment (SunRISE) Mission

The Sun Radio Interferometer Space Experiment (SunRISE) will provide an entirely new view on particle acceleration and transport in the inner heliosphere by creating the first low radio frequency interferometer in space to localize heliospheric radio emissions. By imaging and determining the location of decametric-hectometric (DH) radio bursts from 0.1 MHz–25 MHz, SunRISE will provide key information on particle acceleration mechanisms associated with coronal mass ejections (CMEs) and the magnetic field topology from active regions into interplanetary space. Six small spacecraft, of a 6U form factor, will fly in a supersynchronous geosynchronous Earth orbit (GEO) orbit within about 10 km of each other, in a passive formation, and image the Sun in a portion of the spectrum that is blocked by the ionosphere and cannot be observed from Earth. Key aspects that enable this mission are that only position knowledge of the spacecraft is required, not active control, and that the architecture involves a modest amount of on-board processing coupled with significant ground-based processing for navigation, position determination, and science operations. Mission-enabling advances in software-defined radios, GPS navigation and timing, and small spacecraft technologies, developed and flown on the DARPA High Frequency Research (DHFR), the Community Initiative for Continuing Earth Radio Occultation (CICERO), and the Mars Cube One (MarCO) missions, have made this mission affordable and low-risk. The SunRISE mission will involve utilizing commercial access to space, in which the SunRISE spacecraft will be carried to their target orbit as a secondary payload in conjunction with a larger host spacecraft intended for GEO.

Neilson, Tim↗
NASA NTRSDate not supplied

Expectation vs. Reality: The Sunrise Problem Applied to Probabilistic Risk Assessment

The Sunrise Problem is succinctly stated as a question: “what is the probability that the sun will rise tomorrow?” Attempts to answer this seemingly simple question reveal unexpected incongruities between statistical/probabilistic estimates and “real-world” expectations. Rather than being a purely philosophical problem, similar incongruities can be found in reliability and probabilistic risk assessment (PRA) analyses. These differences between statistical predictions and demonstrated reliability can result in analysis shortcomings that should be addressed and resolved. This presentation will begin by discussing the nature of the Sunrise Problem and how it applies to PRA and reliability. Examples of the Sunrise Problem in a PRA estimate will also be included, along with tips to identify and resolve the shortcomings that result from these anomalous situations.

Sunrise Problem↗
NASA NTRS1995

Satellite observations of zonal electric fields near sunrise in the equatorial ionosphere

We report here on a number of examples of anomalous enhancements of eastward electric fields near sunrise in the equatorial ionospheric F-region. These examples were selected from the data base of the equatorial satellite, San Marco D (1988), which measured ionospheric electric fields during a period of solar minimum. The eastward electric fields reported correspond to vertical plasma drifts. The examples studied here are similar in signature and polarity to the pre-reversal electric field enhancements seen near sunset from ground-based radar systems. The morphology of these sunrise events, which are observed on about 14% of the morning-side satellite passes, are studied as a function of local zonal velocity, magnetic activity, geographic longitude and altitude. The nine events studied occur at locations where the zonal plasma flow is generally measured to be eastward, but reducing as a function of local time and at satellite longitudes where the magnetic declination has the opposite polarity as the declination of the sunrise terminator.

Aggson, T. L.↗
NASA NTRS1971

Rocket measurements of ion and electron densities in the D- and lower E-regions near sunrise

Positive-ion and electron densities were measured in the 75 to 110 km altitude range with the aid of two rockets launched from White Sands near sunrise. The solar zenith angles were 91 and 79 deg respectively. The densities were derived from measurements made by an ion collector and from data obtained with a Faraday rotation technique capable of detecting electrons in the D-region. It has been found that in the 80-95 km altitude range, electron detachment from negative ions takes place mainly at zenith angles of less than 91 deg. The source of the high positive-ion density (N(+) approximately 700/cu cm) at an altitude of 75 km just before sunrise is presumed to be scattered Lyman alpha radiation which is ionizing nitric oxide.

Pedersen, A.↗
NASA NTRS1970

An investigation of the ionospheric D region at sunrise

The growth over sunrise of the C and D layers of the ionosphere is investigated. The model which is analyzed includes the negative ion species O(-), O2(-), O3(-), O4(-), NO3(-), CO3(-), and CO4(-). Ionization sources due to galactic cosmic rays, precipitated electrons, ionization of NO by scattered Lyman alpha radiation, and the direct solar radiation ionization are also included. The photodetachment of most of the negative ions is discussed, as well as the time variation of these parameters. The time variations of the electron, negative ion, and positive ion densities are calculated over sunrise. From these data, the mesospheric C and D layer development is plotted. Several model parameters are varied until the best agreement with experimentally determined electron densities is obtained. The results are discussed in light of several atmospheric parameters including the O and NO concentrations and the electron-ion recombination coefficient.

Turco, R. P.↗
NASA NTRS1971

Rocket measurements of ion and electron densities in the D-region during sunrise.

Results from two rockets launched near sunrise at White Sands, N. Mex., when positive ion and electron densities were measured in the D-region for solar zenith angles of 91 and 79 deg. The measurements cover the height range 80 to 110 km and complement previous vlf observations and rocket measurements of electron density. It is shown that the majority of negative ions in this height range are detached near to after ground sunrise. On the basis of these measurements it is possible to discuss electron affinity of negative ions and ion production functions during twilight.

Pedersen, A.↗
NASA NTRS1975

Determination of nitric oxide concentrations from sunrise E-region electron density measurements

Midlatitude sunrise electron density profiles have been analyzed in order to determine nitric oxide concentrations in the range 100-160 km. In general, the determinations are restricted to heights for which the ionization of nitric oxide by direct solar Lyman-alpha radiation is the main contribution to the growth of the E region. The concentrations obtained are larger, by factors of approximately 3 to 4, than those obtained from the midlatitude airglow measurements of other workers. Concentrations have been obtained from one sunset measurement and these are significantly lower than the sunrise values. The results also give a clear indication of increasing nitric oxide concentrations above 120 km with increasing solar activity.

Monro, P. E.↗
NASA NTRS1989

Stratospheric N2O5 profiles at sunrise and sunset from further analysis of the ATMOS/Spacelab 3 solar spectra

Data obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment during the Spacelab 3 (SL3) mission (April 29 to May 6, 1985) indicated the presence of N2O5 in the stratosphere. This paper presents additional analyses of the ATMOS/SL3 spectra carried out to obtain quantitative information on stratospheric N2O5. Results of this analysis include the detection and measurement of weak N2O5 absorption at sunset in the lower stratosphere, the inversion of a precise (about 10 percent) N2O5 sunrise vertical distribution between 25.5 and 37.5 km altitude, and the identification and measurement of absorption by the N2O5 743/cm band at sunrise. Results confirm model predictions that not all of the N2O5 is photodissociated during the day, except in polar regions during the extended daylight of summer.

Rinsland, C. P.↗
NASA NTRS1990

The sunrise and sunset variation of ClO in the lower stratosphere

The abundances of ClO have been measured, in situ, in the lower stratosphere during sunrise and sunset. Measurements were made with an instrument mounted on the NASA ER-2 aircraft, which was flown at an altitude of 20 km and latitudes between 35 and 47 deg N during a morning and an evening flight. The abundances of ClO were observed over a dynamic range of 20 from a detection threshold of 1 part per trillion volume (pptv). These data confirm the sunrise variation of the photolysis of chlorine nitrate that is predicted by a zero-dimensional photochemical model. They also suggest that the absolute photolysis and termolecular formation of chlorine nitrate occur at rates consistent with nominal ClONO2 and NO2 concentrations.

Brune, W. H.↗