Parker Solar Probe Bibliography

2012

<p>3-D PIC (Particle In Cell) simulations of spacecraft-plasma interactions in the solar wind context of the Solar Probe Plus mission are presented. The SPIS software is used to simulate a simplified probe in the near-Sun environment (at a distance of 0.044 AU or 9.5 <em>R</em><sub>S</sub> from the Sun surface). We begin this study with a cross comparison of SPIS with another PIC code, aiming at providing the static potential structure surrounding a spacecraft in a high photoelectron environment. This paper presents then a sensitivity study using generic SPIS capabilities, investigating the role of some physical phenomena and numerical models. It confirms that in the near- sun environment, the Solar Probe Plus spacecraft would rather be negatively charged, despite the high yield of photoemission. This negative potential is explained through the dense sheath of photoelectrons and secondary electrons both emitted with low energies (2\textendash3 eV). Due to…
2012


<p>The Solar Probe Plus (SP+) mission will approach the Sun as close as 9.5 solar radii in order to understand the origin of the solar corona heating and the acceleration of the solar wind. Submitted to such extreme environmental conditions, a thermal protection system is considered to protect the payload of the SP+ spacecraft. Carbon-based materials are good candidate to fulfill this role and critical point remains the equilibrium temperature reached at perihelion by the heat shield. In this paper, experimental results obtained for the solar absorptivity <em>α</em>, the total hemispherical emissivity <em>ɛ</em> and its ratio <em>α</em>/<em>ɛ</em>, conditioning the equilibrium temperature of the thermal protection system, are presented for different kinds of carbon materials heated at high temperatures with or without vacuum-UV (100\&nbsp;\&lt;\&nbsp;<em>λ</em>\&nbsp;\&lt;\&nbsp;200\&nbsp;nm…
2012


It is proposed that the high-speed nanodust detected by the plasma wave instrument on the STEREO spacecraft could have an origin from the sungrazing comets. Trajectory calculations are performed using a simple analytical coronal magnetic field model to explore the dynamical nature of such charged nanodust in the vicinity of the solar corona. The relevance of this very near-solar source mechanism of nanodust and pickup ions to the Solar Probe Plus mission is also discussed.
2012


We present a method to estimate an upper limit of the mission integrated fluence of hard X-rays (HXRs) produced by solar flares for a probe traveling at heliocentric distances R<1 AU. By using (1) the number and peak of both soft X-ray (SXR) flares and microwave (MW) solar bursts observed during the last three solar cycles, (2) either frequency distributions of HXR flare parameters, or correlations between the HXR fluence and the SXR flare class or the MW burst flux intensity, and (3) virtual launches of the probe at different times throughout the last three solar cycles, we accumulate statistics of the mission-integrated HXR fluences and provide values at the 95\% confidence level. We apply this method to the Solar Probe Plus mission.
2012


A multi-physics computations-based methodology for space debris hypervelocity impact (HVI) damage mitigation is presented. Specifically, improved debris mitigation through development of innovative, lightweight structural designs is described. The methodology has been applied to the design of the Solar Probe Plus (SPP) spacecraft to mitigate extreme solar microdust hypervelocity impacts (50-300 km/s) by the Johns Hopkins University Applied Physics Laboratory (JHU/APL). The methodology combines hydrocode computations of the complex, early-time transient material and structural responses with experimental hypervelocity impact data to directly obtain end-state damage predictions for the requisite hypervelocities that are in excess of available test capabilities (similar to 10 km/s). The computations are validated in the low-velocity regime (<10 km/s) by direct HVI testing and verified in the high-velocity regime (50-300 km/s) by comparisons with bounding energy calculations and…
2012


2011

<p>The expansion of a coronal hole filled with a discrete number of higher density coronal plumes is simulated using a time-dependent two-dimensional code. A solar wind model including an exponential coronal heating function and a flux of Alfv\ en waves propagating both inside and outside the structures is taken as a basic state. Different plasma plume profiles are obtained by using different scale heights for the heating rates. Remote sensing and solar wind in situ observations are used to constrain the parameter range of the study. Time dependence due to plume ignition and disappearance is also discussed. Velocity differences of the order of 50 km s<sup>-1</sup>, such as those found in microstreams in the high-speed solar wind, may be easily explained by slightly different heat deposition profiles in different plumes. Statistical pressure balance in the fast wind data may be masked by the large variety of body and surface waves which the higher density filaments…
2011


<p>A method to estimate both solar energetic particle mission-integrated fluences and solar energetic particle peak intensities for missions traveling through the innermost part of the heliosphere (r \&lt; 1 AU) is presented. By using (1) an extensive data set of particle intensities measured at 1 AU over the last three solar cycles, (2) successive launch dates for the mission traveling close to the Sun over the time interval spanned by our data set, and (3) appropriate radial dependences to extrapolate fluences and peak intensities measured at 1 AU to the heliocentric radial distance of the mission at each specific time, we generate distributions of both mission-integrated fluences and maximum peak intensities. From these distributions we extract the values of mission-integrated fluence and maximum peak intensity at a required confidence level. Results of this method applied to the specific case of the nominal prime mission of Solar Probe Plus are shown.</p>
2011


<p>The aim of the Solar Probe Plus (SP+) mission is to understand how the solar corona is heated and how the solar wind is accelerated. To achieve these goals, in situ measurements are necessary and the spacecraft has to approach the Sun as close as 9.5 solar radii. This trajectory induces extreme environmental conditions such as high temperatures and intense Vacuum Ultraviolet radiation (VUV). To protect the measurement and communication instruments, a heat shield constituted of a carbon material is placed on the top of the probe. In this study, the physical and chemical behavior of carbon materials is experimentally investigated under high temperatures (1600-2100 K), high vacuum (10<sup>-4</sup> Pa) and VUV radiation in conditions near those at perihelion for SP+. Thanks to several in situ and ex situ characterizations, it was found that VUV radiation induced modification of outgassing and of mass loss rate together with alteration of microstructure and morphology…
2011


In this paper, the concentrated solar energy is used as a source of high temperatures to study the physical and chemical behaviors and intrinsic properties of refractory materials. The atmospheres surrounding the materials have to be simulated in experimental reactors to characterize the materials in real environments. Several application fields are concerned such as the aerospace and the energy fields: examples of results will be given for the heat shield of the Solar Probe Plus mission (NASA) for the SiC/SiC material that can be used as cladding materials for next nuclear reactor (gas-cooled fast reactor-GFR, Generation IV) and for new advanced materials for solar absorbers in concentration solar power (CSP) plant. Two different facilities-REHPTS and MEDIASE-implemented at the focus of two different solar furnaces of the PROMES-CNRS laboratory-5 kW and 1 MW-are presented together with some experimental results on the behavior of high temperature materials. [DOI: 10.1115/1.4004241]
2011


2010

<p>Magnetic field reconnection is often invoked to explain electromagnetic energy conversion in planetary magnetospheres, stellar coronae, and other astrophysical objects. Because of the huge dynamic range of magnetic fields in these bodies, it is important to understand energy conversion as a function of magnetic field strength and related parameters. It is conjectured theoretically and shown experimentally that the energy conversion rate per unit area in reconnection scales as the cube of an appropriately weighted magnetic field strength divided by the square root of an appropriately weighted density. With this functional dependence, the energy release in flares on the Sun, the large and rapid variation of the magnetic flux in the tail of Mercury, and the apparent absence of reconnection on Jupiter and Saturn, may be understood. Electric fields at the perihelion of the Solar Probe Plus mission may be tens of V/m.</p>
2010


<p>NASA plans to launch the first mission to the Sun, named Solar Probe Plus, as early as 2015, after a comprehensive feasibility study that significantly changed the original Solar Probe mission concept. The original Solar Probe mission concept, based on a Jupiter gravity assist trajectory, was no longer feasible under the new guidelines given to the mission. A complete redesign of the mission was required, which called for developing alternative trajectories that excluded a flyby of Jupiter. Without the very powerful gravity assist from Jupiter it was extremely difficult to get to the Sun, so designing a trajectory to reach the Sun that is technically feasible under the new mission guidelines became a key enabler to this highly challenging mission. Mission design requirements and challenges unique to this mission are reviewed and discussed, including various mission scenarios and six different trajectory designs utilizing various planetary gravity assists that were considered…
2010


<p>A three-dimensional, self-consistent code is employed to solve for the static potential structure surrounding a spacecraft in a high photoelectron environment. The numerical solutions show that, under certain conditions, a spacecraft can take on a negative potential in spite of strong photoelectron currents. The negative potential is due to an electrostatic barrier near the surface of the spacecraft that can reflect a large fraction of the photoelectron flux back to the spacecraft. This electrostatic barrier forms if (1) the photoelectron density at the surface of the spacecraft greatly exceeds the ambient plasma density, (2) the spacecraft size is significantly larger than local Debye length of the photoelectrons, and (3) the thermal electron energy is much larger than the characteristic energy of the escaping photoelectrons. All of these conditions are present near the Sun. The numerical solutions also show that the spacecraft\textquoterights negative potential can be…
2010


The Solar Probe Plus (SPP) spacecraft will orbit as closely as 9.5 solar radii from the sun; so close that its thermal protection shield (TPS) will reach a peak temperature of 1,400C. To work in this environment, the solar array will use pressurized water cooling and operate in the penumbra formed by the TPS at a 68 degrees angle of incidence. Even with these mitigations, the array will be subject to extremely high intensity and temperature. This paper will summarize the array s environment, present a preliminary design, outline development plans and describe phase A test plans.
2010


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1986

<p>This paper reports on the transient photocurrent measurements made with test structures fabricated on sapphire substrates, and the computer simulation model which was developed to use the test results. Predictions of logic upset for a 4 K RAM CMOS/SOS compared with measured upset rates showed agreement within a factor of 2. The test structure results indicate that the sapphire photoconductance is 6.3 x 10 to the -19th mhos/(rads/s)-micron. The use of this value in the present simulation model will increase the predicted upset rate, and thus, increase the disagreement by more than a factor of two.</p>
1986