Parker Solar Probe Bibliography

2014

<p>We have constructed a semi-analytical model of the energetic-ion foreshock of a CME-driven coronal/interplanetary shock wave responsible for the acceleration of large solar energetic particle (SEP) events. The model is based on the analytical model of diffusive shock acceleration of Bell (1978), appended with a temporal dependence of the cut-off momentum of the energetic particles accelerated at the shock, derived from the theory. Parameters of the model are re-calibrated using a fully time-dependent self-consistent simulation model of the coupled particle acceleration and Alfv\ en-wave generation upstream of the shock. Our results show that analytical estimates of the cut-off energy resulting from the simplified theory and frequently used in SEP modelling are overestimating the cut-off momentum at the shock by one order magnitude. We show also that the cut-off momentum observed remotely far upstream of the shock (e.g., at 1 AU) can be used to infer the properties of the…
2014


<p>Solar Probe Plus, scheduled to launch in 2018, is a NASA mission that will fly through the Sun\textquoterights atmosphere for the first time. It will employ a combination of in situ plasma measurements and remote sensing imaging to achieve the mission\textquoterights primary goal: to understand how the Sun\textquoterights corona is heated and how the solar wind is accelerated. The Solar Wind Electrons Alphas and Protons (SWEAP) instrument suite consists of a Faraday cup and three electrostatic analyzers. In order to accomplish the science objectives, an encounter-based operations scheme is needed. This paper will outline the SWEAP science operations center design and schemes for data selection and down link. \textcopyright (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.</p>
2014


<p>The interpretation of single-point spacecraft measurements of solar wind turbulence is complicated by the fact that the measurements are made in a frame of reference in relative motion with respect to the turbulent plasma. The Taylor hypothesis\textemdashthat temporal fluctuations measured by a stationary probe in a rapidly flowing fluid are dominated by the advection of spatial structures in the fluid rest frame\textemdashis often assumed to simplify the analysis. But measurements of turbulence in upcoming missions, such as Solar Probe Plus, threaten to violate the Taylor hypothesis, either due to slow flow of the plasma with respect to the spacecraft or to the dispersive nature of the plasma fluctuations at small scales. Assuming that the frequency of the turbulent fluctuations is characterized by the frequency of the linear waves supported by the plasma, we evaluate the validity of the Taylor hypothesis for the linear kinetic wave modes in the weakly collisional solar wind…
2014


<p>Motivated by the upcoming Solar Orbiter and Solar Probe Plus missions, qualitative and quantitative predictions are made for the effects of the violation of the Taylor hypothesis on the magnetic energy frequency spectrum measured in the near-Sun environment. The synthetic spacecraft data method is used to predict observational signatures of the violation for critically balanced Alfv\ enic turbulence or parallel fast/whistler turbulence. The violation of the Taylor hypothesis can occur in the slow flow regime, leading to a shift of the entire spectrum to higher frequencies, or in the dispersive regime, in which the dissipation range spectrum flattens at high frequencies. It is found that Alfv\ enic turbulence will not significantly violate the Taylor hypothesis, but whistler turbulence will. The flattening of the frequency spectrum is therefore a key observational signature for fast/whistler turbulence.</p>
2014


2013

<p>The solar and space physics community has recently completed its second decadal survey under the auspices of the National Research Council. An integrated strategy for ground and space based studies of the Sun and space physics has been recommended, with specific recommendations made regarding new instrumentation, programs, and facilities. The ground based component of these recommendations is briefly reviewed here: the Advanced Technology Solar Telescope (ATST), the Frequency Agile Solar Radiotelescope (FASR), and the Coronal Solar Magnetism Observatory (COSMO). Although not considered as part of the decadal portfolio, but of which the community should nevertheless be aware, are the Atacama Large Millimeter/submillimeter Array (ALMA) and the Jansky Very Large Array (VLA). Several additional instruments are briefly mentioned as pathfinders for those instruments recommended by the decadal survey, including the Coronal Multichannel Polarimeter (CoMP) and the Expanded Owens…
2013


<p>The NASA Solar Probe Plus (SPP) mission will be the first spacecraft to pass through the sub-Alfv\ enic solar corona. The objectives of the mission are to trace the flow of energy that heats and accelerates the solar corona and solar wind, to determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind, and to explore mechanisms that accelerate and transport energetic particles. The Solar Wind Electrons, Alphas, and Protons (SWEAP) Investigation instrument suite on SPP will measure the bulk solar wind conditions in the inner heliosphere. SWEAP consists of the Solar Probe Cup (SPC), a sun-pointing Faraday Cup, and the Solar Probe ANalyzers (SPAN), a set of 3 electrostatic analyzers that will reside in the penumbra of SPP\textquoterights thermal protection system and measure solar wind ions and electrons. SPP is scheduled to launch in 2018 into an equatorial solar orbit where a sequence of Venus gravity assists will gradually lower its…
2013


<p>We present a new data analysis method enabling the observation of magnetic field fluctuations associated with temperature anisotropy instabilities using the Ulysses spacecraft. The movement of the spacecraft away from the Sun causes the observed plasma conditions, turbulent fluctuation amplitude, magnetic field strength and important physical scales to change. We normalize wavelet power spectra of the magnetic field using local values for the proton gyroscale and large scale magnetic field fluctuation amplitude to remove the effects of varying heliocentric distance. We recover the enhancement of magnetic fluctuations where temperature anisotropy instability growth rates are large, as seen by previous studies in the ecliptic at 1 AU. This method can be applied to any spacecraft data that contains large changes in physical scales, magnetic field strength or other plasma parameters, for example the upcoming Solar Orbiter and Solar Probe Plus missions.</p>
2013


<p>Solar flare accelerated electrons escaping into the interplanetary space and seen as type III solar radio bursts are often detected near the Earth. Using numerical simulations we consider the evolution of energetic electron spectrum in the inner heliosphere and near the Earth. The role of Langmuir wave generation, heliospheric plasma density fluctuations, and expansion of magnetic field lines on the electron peak flux and fluence spectra is studied to predict the electron properties as could be observed by Solar Orbiter and Solar Probe Plus. Considering various energy loss mechanisms we show that the substantial part of the initial energetic electron energy is lost via wave-plasma processes due to plasma inhomogeneity. For the parameters adopted, the results show that the electron spectrum changes mostly at the distances before ̃ 20 R <sub>☉</sub>. Further into the heliosphere, the electron flux spectrum of electrons forms a broken power law relatively similar to…
2013


The Solar Probe Cup (SPC) Instrument is a Sun-facing Faraday Cup instrument slated for launch aboard the Solar Probe Plus (SPP) spacecraft in 2018. SPC is one of two instruments onboard the Solar Wind Electrons Alphas Protons (SWEAP) instrument suite and is the only SPP charged particle instrument that will not be shielded behind the spacecraft s Thermal Protection System (TPS). The 7-year SPP mission will take SPC on 24 solar encounters at perihelia ranging from 35 to 9.86 solar radii (R-S). The SPC components will encounter a large range of temperatures, from in excess of 1500 degrees C at perihelion to -130 degrees C at or near aphelion. This paper details the derived mechanical and structural requirements on the primary SPC mechanical assemblies including its thermal shield, the sensor unit and the strut/adapter assembly. An example of sensor requirements derivation to the component level is provided by the modulator flex ring. Preliminary requirements derivation, definition, and…
2013


This paper describes the implementation of a solar simulator, know as the Solar Environment Simulator (SES), that can simulate solar flux levels up to those encountered at 9.8 solar radii. The paper outlines the design, and the challenges of realizing the SES. It also describes its initial uses for proving out the design of the Solar Winds Electrons, Alphas, and Protons (SWEAP) Faraday cup. The upcoming Solar Probe Plus (SPP) mission requires that its in-situ plasma instrument (the Faraday Cup) survive and operate over an unprecedented range of temperatures. One of the key risk mitigation activities during Phase B has been to develop and implement a simulator that will enable thermal testing of the Faraday Cup under flight-like conditions. While still in the initial start-up, the SES has proven to be an instrumental component in the process of predicting the in-flight performance of the SWEAP Faraday Cup. With near continuously variable power control above the threshold of 1.6kW/lamp…
2013


In this paper, the electrostatic sheath of a simplified spacecraft is investigated for heliocentric distances varying from 0.044 to 1 AU, using the 3-D Particle in Cell software Satellite-Plasma Interaction System. The baseline context is the prediction of sheath effects on solar wind measurements for various missions, including the Solar Probe Plus mission (perihelion at 0.044 AU from the sun) and Solar Orbiter (SO) (perihelion at 0.28 AU). The electrostatic sheath and the spacecraft potential could interfere with the low-energy (a few tens of eV) plasma measurements, by biasing the particle distribution functions measured by the detectors. If the spacecraft charges to large negative potentials, the problem will be more severe as low-energy electrons will not be seen at all. The Solar Probe Plus and SO cases will be presented in details and extended to other distances through a parametric study, to investigate the influence of the heliocentric distance to spacecraft. Our main result…
2013


The upcoming Solar Probe Plus (SPP) mission requires novel approaches for in-situ plasma instrument design. SPP s Solar Probe Cup (SPC) instrument will, as part of the Solar Wind Electrons, Alphas, and Protons (SWEAP) instrument suite, operate over an enormous range of temperatures, yet must still accurately measure currents below 1 pico-amp, and with modest power requirements. This paper discusses some of the key technology development aspects of the SPC, a Faraday Cup and one of the few instruments on SPP that is directly exposed to the solar disk, where at closest approach to the Sun (less than 10 solar radii (R-s) from the center of the Sun) the intensity is greater than 475 earth-suns. These challenges range from materials characterization at temperatures in excess of 1400 degrees C to thermal modeling of the behavior of the materials and their interactions at these temperatures. We discuss the trades that have resulted in the material selection for the current design of the…
2013


This paper presents a methodology for the selection of critical design-parameters for the design of Micro Meteoroid and Orbital Debris (MMOD) spacecraft protection based on a modified implementation of the concept of the Probability of No Impact (PNI). The PNI methodology, based on Poisson s discrete statistics, has been widely used to determine critical particle sizes for the design of protection systems. However, it does not provide guidelines for the selection of the design impact speed, especially when the impact speed has a very wide statistical distribution like that encountered in interplanetary missions. The modifications to the PNI methodology presented here allows for the selection of both, a design particle size and impact speed, based on the same discrete probability theory. This methodology is applied to determine critical design parameters for the Solar Probe Plus (SPP) spacecraft; a mission currently under study funded by the NASA s Office of Space Science - Sun-Earth…
2013


Titanium alloy, Ti-6Al-4V, and commercially pure (CP) Titanium will be used to protect the Solar Probe Plus (SPP) spacecraft against hypervelocity impacts by solar dust particles. The results of six hypervelocity impact (HVI) tests performed on Ti-6Al-4V and CP monolithic samples (3 each) arc evaluated in terms of cratering and spall damage, and compared with crater depth and spall initiation predictions using the Ballistic Limit Equation (BLE) for Titanium shields developed at NASA Johnson Space Center and hydrocode computations. In the tests, 2017-T4 aluminum spheres with a diameter of 2.35 mm were used to impact the shields at an impact velocity of about 7 km/s. In general, the measured and predicted values of crater depth are found to be in good agreement with each other, regardless of the type of Titanium alloy. In terms of spall damage, two of the three Ti-6Al-4V samples exhibit a noticeable incipient spall and one sample shows a very faint incipient spall, whereas only one of…
2013


2012