Parker Solar Probe Bibliography

2016

A method to measure an antenna s performance when mounted to an electrically large and complex-shaped spacecraft is described. In the past, either time-intensive numerical simulations or antenna range measurements of an expensive full-scale model of the spacecraft were used to determine the antenna s performance. An alternative method fabricated a reduced-size scaled spacecraft model using 3-D printing processes. The antenna is also reduced in size by the same scale factor as the spacecraft, but the frequency of operation is increased. This combination of a reduced model and increased radiation frequency is equivalent to the full-scale model in terms of scattering. This approach was used to characterize the degradation of an X-Band low gain antenna (LGA) on NASA s Solar Probe Plus (SPP) Spacecraft. The spacecraft and antenna model were reduced in size by a factor of 4.51 and the radiation frequency was scaled upwards by 4.51, from X-Band to Ka-Band. The model was then measured in a…
2016


The migration to Ka-band for science downlink on deep space missions increases data rates significantly, but also presents new challenges to radio and RF system designers. One challenge is to maintain low carrier phase noise on a coherent downlink. Thermal noise on the X-band uplink that is within the bandwidth of the carrier recovery process modulates the phase of the coherent downlink. For missions that use X-band for command uplink and Ka-band for science downlink, such as the NASA Solar Probe Plus mission, the ratio of downlink to uplink frequency acts as a phase noise multiplier on the coherent downlink. Analysis and prototype tests revealed that the additional phase noise degraded both telemetry and navigation performance significantly. Accordingly, an additional software filter is inserted into the Ka-band coherent turnaround path. This filter constrains the phase noise sufficiently to meet all communication and navigation requirements. In this paper we describe the phase noise…
2016


The Solar Probe Plus (SPP) mission to be launched in 2018 is designed to use CFDP (CCSDS File Delivery Protocol) Class 2 Reliable Transfer in the majority of spacecraft commanding as well as for playback of recorded telemetry. A prioritized SSR telemetry playback interface using CFDP was developed on MESSENGER and Van Allen Probes and will be reused on SPP. Similar to MESSENGER, telemetry files of instrument data will be provided directly to the appropriate Science Operations Center (SOC) and not processed by the Mission Operations Center (MOC). The SPP flight software is built to process command files and CCSDS Telecommand packets. The SPP Ground Software has a Database of Commands to create Telecommand packets. SPP will support the Expedited Service (BD Service) of the CCSDS Communications Operations Procedure-1 (COP-1) commanding but will not use the Sequence-Controlled Service (AD Service) of COP-1 commanding. The COP-1 AD Service is not well suited for deep space without…
2016


Deep-space missions typically use a radio link between the Deep Space Network (DSN) ground stations and the spacecraft to transmit telemetry data and to generate the range and Doppler shift measurements that enable precise navigation. The amount of carrier phase noise present in this radio link is an important metric of performance, and radios are often designed to minimize the impact of this noise. From a communication perspective, more noise causes an increase in the system s frame-error rate, and from a navigation perspective more noise causes larger errors in the range and Doppler shift measurements. A thorough understanding of how carrier phase noise enters the spacecraft radio system and how that noise is modified during the communication process enables the radio designers to build a better system. This paper contributes to the current body of knowledge on turnaround noise for Deep Space communication and Doppler data, and how to mitigate the resulting performance degradation.…
2016


2015

<p>Knowledge of the electron density distribution in the solar corona put constraints on the magnetic field configurations for coronal modeling and on initial conditions for solar wind modeling. We work with polarized SOHO/LASCO-C2 images from the last two recent minima of solar activity (1996-1997 and 2008-2010), devoid of coronal mass ejections. The goals are to derive the 4D electron density distributions in the corona by applying a newly developed time-dependent tomographic reconstruction method and to compare the results between the two solar minima and with two magnetohydrodynamic models. First, we confirm that the values of the density distribution in thermodynamic models are more realistic than in polytropic ones. The tomography provides more accurate distributions in the polar regions, and we find that the density in tomographic and thermodynamic solutions varies with the solar cycle in both polar and equatorial regions. Second, we find that the highest-density…
2015


<p>The evolution of the ion-scale plasma turbulence in the inner heliosphere is studied by associating the plasma parameters for hybrid-code turbulence simulations to the radial distance from the Sun via a Solar wind model based mapping procedure. Using a mapping based on a one-dimensional solar wind expansion model, the resulting ion-kinetic scale turbulence is related to the solar wind distance from the Sun. For this purpose the mapping is carried out for various values of ion beta that correspond to the heliocentric distance. It is shown that the relevant normal modes such as ion cyclotron and ion Bernstein modes will occur first at radial distances of about 0.2-0.3 AU, i.e., near the Mercury orbit. This finding can be used as a reference, a prediction to guide the in situ measurements to be performed by the upcoming Solar Orbiter and Solar Probe Plus missions. Furthermore, a radial dependence of the wave-vector anisotropy was obtained. For astrophysical objects this means…
2015


<p>We extend the kinetic guiding-center model of collisionless coronal hole protons presented in Isenberg \&amp; Vasquez to consider driving by imbalanced spectra of obliquely propagating ion-cyclotron waves. These waves are assumed to be a small by-product of the imbalanced turbulent cascade to high perpendicular wavenumber, and their total intensity is taken to be 1\% of the total fluctuation energy. We also extend the kinetic solutions for the proton distribution function in the resulting fast solar wind to heliocentric distances of 20 solar radii, which will be attainable by the Solar Probe Plus spacecraft. We consider three ratios of outward-propagating to inward-propagating resonant intensities: 1, 4, and 9. The self-consistent bulk flow speed reaches fast solar wind values in all cases, and these speeds are basically independent of the intensity ratio. The steady-state proton distribution is highly organized into nested constant-density shells by the resonant wave-…
2015


<p>The Solar Probe Plus (SPP) spacecraft will explore the near-Sun environment, reaching heliocentric distances less than 10 R<sub>☉ </sub>. Near Earth, spacecraft measurements of fluctuating velocities and magnetic fields taken in the time domain are translated into information about the spatial structure of the solar wind via Taylor\textquoterights \textquotedblleftfrozen turbulence\textquotedblright hypothesis. Near the perihelion of SPP, however, the solar-wind speed is comparable to the Alfv\ en speed, and Taylor\textquoterights hypothesis in its usual form does not apply. In this paper, we show that under certain assumptions, a modified version of Taylor\textquoterights hypothesis can be recovered in the near-Sun region. We consider only the transverse, non-compressive component of the fluctuations at length scales exceeding the proton gyroradius, and we describe these fluctuations using an approximate theoretical framework developed by Heinemann and Olbert. We…
2015


<p>The Solar Orbiter and Solar Probe Plus missions will provide observations of magnetic clouds closer to the Sun than ever before, and it will be good preparation for these missions to make full use of the most recent in situ data sets from the inner heliosphere\textemdashnamely, those provided by MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and Venus Express\textemdashfor magnetic cloud studies. We present observations of the same magnetic cloud made by MESSENGER at Mercury and later by Solar TErrestrial RElations Observatory-B (STEREO-B), while the spacecraft were radially aligned in 2011 November. Few such radial observations of magnetic clouds have been previously reported. Estimates of the solar wind speed at MESSENGER are also presented, calculated through the application of a previously established technique. The cloud\textquoterights flux rope has been analyzed using force-free fitting; the rope diameter increased from 0.18 to 0.41 AU (…
2015


<p>The paper provides a review of the state of the art and prospects of space research in heliophysics, in which a pivotal role belongs to magnetic measurements in the Sun and heliosphere. New space missions, such as the Interhelioprobe, Solar Orbiter, Solar Probe Plus, etc., will follow the currently operating ones (Hinode, SDO, STEREO, etc.) to observe the Sun from short distances and from out-of-ecliptic positions, as well as to conduct in situ measurements in the vicinity of the Sun and outside the ecliptic. The planned coordinated observations within the framework of these missions will allow us to explore the structure and dynamics of magnetic fields in the polar regions of the Sun, to study the mechanisms of the solar dynamo and solar cycle, to gain a deeper insight into the process of corona heating and acceleration of the solar wind, and to get a response to a number of other pressing issues of heliophysics.</p>
2015


<p>The Solar Wind Electrons Alphas and Protons (SWEAP) Investigation on Solar Probe Plus is a four sensor instrument suite that provides complete measurements of the electrons and ionized helium and hydrogen that constitute the bulk of solar wind and coronal plasma. SWEAP consists of the Solar Probe Cup (SPC) and the Solar Probe Analyzers (SPAN). SPC is a Faraday Cup that looks directly at the Sun and measures ion and electron fluxes and flow angles as a function of energy. SPAN consists of an ion and electron electrostatic analyzer (ESA) on the ram side of SPP (SPAN-A) and an electron ESA on the anti-ram side (SPAN-B). The SPAN-A ion ESA has a time of flight section that enables it to sort particles by their mass/charge ratio, permitting differentiation of ion species. SPAN-A and -B are rotated relative to one another so their broad fields of view combine like the seams on a baseball to view the entire sky except for the region obscured by the heat shield and covered by SPC.…
2015


<p>recent studies suggest that magnetic reconnection is able to erode substantial amounts of the outer magnetic flux of interplanetary magnetic clouds (MCs) as they propagate in the heliosphere. We quantify and provide a broader context to this process, starting from 263 tabulated interplanetary coronal mass ejections, including MCs, observed over a time period covering 17 years and at a distance of 1 AU from the Sun with Wind (1995-2008) and the two STEREO (2009-2012) spacecraft. Based on several quality factors, including careful determination of the MC boundaries and main magnetic flux rope axes, an analysis of the azimuthal flux imbalance expected from erosion by magnetic reconnection was performed on a subset of 50 MCs. The results suggest that MCs may be eroded at the front or at rear and in similar proportions, with a significant average erosion of about 40\% of the total azimuthal magnetic flux. We also searched for in situ signatures of magnetic reconnection causing…
2015


As a NASA mission to touch the sun Solar Probe Plus (SPP) reveals challenges previously not encountered in space solar panel design and testing. Simulating flight conditions require new testing methods and equipment which have been specifically developed for this unique PV application. Testing under high intensity, high temperature conditions over large areas poses design and logistic challenges, while testing cell performance degradation to a measurement level error of <1% involved fabrication of custom LED simulators.<br/> &copy; 2015 IEEE.
2015


The size of relatively large dynamic conchoidal fractures, i.e., surface spalls, immediately adjacent to and around interplanetary dust (IDP) hypervelocity impact (HVI) craters or pits in glass substrates is relevant to spacecraft solar cell and science instrument lens performance metrics, as well as glass pane design and safety in manned missions. This paper presents an analysis of the diameter of surface spalls in glass for the Solar Probe Plus (SPP) spacecraft, whose solar arrays and instruments must survive a 7-year mission involving significant dust interaction. Previously published data and regressions for surface spalling obtained from ground-HVI-tested and space-returned glass samples and solar cells are collated for this purpose. Analysis of the collective dataset reveals an unexpected and design-relevant finding: spall diameter, D-S, obtained with dust-scale particles (diameter, d(P) < 55 mu m) and solar cells scales differently with impact velocity as compared with…
2015


As part of a larger effort led by the Keck Institute for Space Studies at the California Institute of Technology, the Advanced Concepts Office at NASA&rsquo;s George C. Marshall Space Flight Center conducted a study to assess what low-thrust advanced propulsion system candidates, existing and near term, could deliver a small, Voyager-like satellite to our solar system&rsquo;s heliopause, approximately 100 AU from the center of the sun, within 10 years and within a 2025 to 2035 launch window. The advanced propulsion system trade study consisted of three candidates, including a Magnetically Shielded Miniature (MaSMi) Hall thruster, a solar sail and an electric sail. Two aerial densities, and thus characteristic accelerations, 0.426 mm/s<sup>2</sup> and 0.664 mm/s<sup>2</sup>, were analyzed for the solar sail option in order understand the impact of near and long term development of this technology. Similarly, two characteristic accelerations, 1 mm/s<…
2015


Past papers demonstrated advancements made on developing scientific PMOS/NMOS CMOS imagers that match or exceed CCD performance. New data and discussions presented in this paper present further progress on subject matters that include: 1). subcarrier read noise performance with understandings for how the noise floor can be reduced further, 2). comprehensive correlated double sampling (CDS) signal processing noise fundamentals in response to random telegraph and flicker noise sources, 3). high energy radiation damage test data from NASA s BSI SoloHi/WISPR CMOS imager and 4). update on a new scientific BSI PMOS/NMOS stitched Mk x Nk x 10 um 5TPPD pixel imager being fabricated for Lawrence Livermore National Lab (LLNL) and NASA s Europa Clipper mission.
2015


Three metallic coatings with textured surfaces, made of rhenium, tungsten and molybdenum, were studied in the frame of the Solar Probe Plus mission (NASA) as candidate materials. The role of these coatings is to dissipate a maximum of energy from a hot instrument facing the Sun, by the mean of their high total hemispherical emissivity. The total hemispherical emissivity of the three coatings was measured in the temperature range 1100-1900 K, as well as over time in order to study their high temperature stability. Various emissivity levels were obtained depending on the surface texture. The highest total hemispherical emissivity was obtained on a rhenium coating, with an emissivity of 0.8 in the temperature range 1300-1700 K. However, this rhenium coating with a fine, sharp surface texture, presented an instability at high temperature, which might limit its optimal operating temperature to about 1500 K. As for the tungsten coating, the total hemispherical emissivity was increased by a…
2015


The Solar Probe Plus mission (NASA) will be the first mission to enter the solar corona. The spacecraft will orbit the Sun at 8.5 solar radii from the Sun s surface at closest approach. Some metallic parts of the two on-board instruments, SWEAP (a Faraday cup) and FIELDS (antennas), will directly face the Sun, while the rest of the payload will be protected by a heat shield. For application to these instruments, a candidate refractory material, tungsten, was studied, confronting conditions similar to the ones expected close to the Sun: high radiative flux leading to high temperatures (1100-2500 K) and proton bombardment (1 and 4 keV; 10(16), 10(17) and 10(18) ions m(-2) s(-1)) to simulate the solar wind in high vacuum (10(-4) Pa). Total directional and hemispherical emissivities in the two wavelength ranges 0.6-2.8 and 0.6-40 mu m were recorded in situ during treatments. Material characterization was performed before and after each high temperature and bombardment experiment to…
2015


The size of relatively large dynamic conchoidal fractures, i.e., surface spalls, immediately adjacent to and around interplanetary dust (IDP) hypervelocity impact (HVI) craters or pits in glass substrates is relevant to spacecraft solar cell and science instrument lens performance metrics, as well as glass pane design and safety in manned missions. This paper presents an analysis of the diameter of surface spalls in glass for the Solar Probe Plus (SPP) spacecraft, whose solar arrays and instruments must survive a 7-year mission involving significant dust interaction. Previously published data and regressions for surface spalling obtained from ground-HVI-tested and space-returned glass samples and solar cells are collated for this purpose. Analysis of the collective dataset reveals an unexpected and design-relevant finding: spall diameter, D<inf>S</inf>, obtained with dust-scale particles (diameter, d<inf>P</inf>< 55 &mu;m) and solar cells scales…
2015


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


The Solar Probe Plus (SPP) mission, under NASA&rsquo;s Living With a Star program, will fly a spacecraft (S/C) through the sun&rsquo;s outer corona with orbit perihelia that gradually approach as close as 9.86 solar radii from the center of the sun. The mission will gather data on the processes of coronal heating, solar wind acceleration, and production, evolution, and transport of solar energetic particles. The S/C is powered by two actively cooled photovoltaic solar array (S/A) wings. Because of the extreme environments near the sun, the S/C body is protected behind a solar shield, which the wings will utilize to provide shading in the penumbra behind the solar shield the wings will also tilt at a high angle of incidence to the sun. The S/A power and temperature are extremely sensitive to the wing angle, S/C pointing variations, mechanical vibrations, sun distance, and other environmental disturbances in these harsh conditions. A novel S/A control algorithm autonomously…
2014


Aerogravity assist is an orbital transfer technique that enhances the effect of gravity assist maneuvers by utilizing aerodynamic lift in addition to gravity. This enables greater turning angles from a planetary assist, potentially cutting years off a conventional gravity assisted trajectory with multiple flybys or significantly reducing required launch C<inf>3</inf>. One of the major challenges are the extreme heat loads and heat fluxes present when flying through atmospheres at interplanetary speeds. Incorporating an active cooling system and reusing the heated coolant as propellant may be an elegant way to address both the heating and drag loss problems simultaneously. This concept is explored in the context of the Solar Probe mission, which aims to send a spacecraft to a close orbit of the Sun. The aerodynamic, aerothermal, cooling, and propulsion requirements are examined for a 44 solar radii perihelion trajectory and a notional vehicle concept is presented.<br/>
2014


The Solar Probe Plus (SPP) spacecraft is expected to encounter unprecedented levels of interplanetary dust particle (IDP) exposure during its approximately 7-year journey. To assure mission success it is necessary to define the dust hypervelocity impact (HVI) protection levels provided by its Multi-Layer Insulation (MLI)/thermal blankets with a reliability that is on par with that available for metallic Whipple shields. Development of a new ballistic limit equation (BLE) in the 7-150 km/s HVI range for representative 2-wall Whipple shields in which spacecraft MLI is the bumper material impacted by fused silica dust, was necessitated and is presented. A baseline SPP configuration was adopted for analysis: 0.0176 cm-thk. Kapton bumper (monolithic and layered), 2.54 cm standoff and 0.0762 cm-thk. Ti-6Al-4V rear wall. With a solid Kapton bumper, the critical particle diameter for incipient spall, which is chosen to be the failure criterion for SPP, is found to be in the &sim;650-1100…
2014


The Johns Hopkins University Applied Physics Laboratory (JHU/APL) is dedicated to solving critical challenges as set forth by the National Aeronautics and Space Administration and the Department of Defense. JHU/APL participates fully in the nation s formulation of space science and exploration priorities, providing the needed science, engineering, and technology, including the production and operation of unique spacecraft, instruments, and subsystems. Built in 1983, JHU/APL s spacecraft integration and test facility has supported numerous successful missions ranging from the first, GEOSAT-A, which launched in 1985, to the most recent, Van Allen Probes, which launched in 2012. But even with all of the successful spacecraft developed in the facility, the building was beginning to show its limitations in terms of its ability to support larger, more complex missions. It became apparent in 2008 that additional spacecraft and instrument development facilities were desperately needed in…
2014


Downlink scheduling methods that minimize either contact time or data latency are described. For deep-space missions these two methods yield very different schedules. Optimal scheduling algorithms are straightforward for ideal mission scenarios. In practice, additional schedule requirements preclude a tractable optimal algorithm. In lieu of an optimal solution, an iterative sub-optimal algorithm is described. These methods are motivated in part by a need to balance mission risk, which increases with data latency, and mission cost, which increases with contact time. Cost is reduced by delaying downlink contacts until higher data rates are available. Previous work described optimization of individual Ka-band contacts in the presence of time-varying and statistical link parameters. The present study builds on previous work by using a downlink capacity profile to optimize the downlink schedule over the duration of a mission. The downlink schedule for the NASA mission Solar Probe Plus is…
2014


The spacecraft for the Solar Probe Plus mission, due to launch in 2018, will encounter an extreme near-Sun thermal and plasma environment. Outgassing of materials such as silicone adhesives in this previously unexplored environment can result in deposits on solar arrays, instrument components, and other sensitive spacecraft surfaces. Array surfaces exposed to UV can cause those deposits to be fixed to the surface, degrading their performance. To assess the severity of the deposits, the Solar Probe Plus program has undertaken a wholespacecraft modeling effort. At the Applied Physics Laboratory (APL), we have built a geometrical model of the spacecraft, selected appropriate material properties, and used the outgassing module of the Systema modeling package to evaluate emission and deposition of silicone. Presented here are the methods and results from the modeling effort.<br/>
2014


Predicting the output of the Solar Probe Plus (SPP) solar array presents unique challenges as the array operates at very high temperatures and irradiances, and has a water-cooled substrate. A further complication arises because, close to perihelion, each string operates at an irradiance and temperature different from the other strings. This paper provides the methodology and results for computing the output of the array over a range of irradiances from zero to seventy suns, temperatures from -80&deg;C to 164&deg;C, and angles of up to 70&deg; between the array normal and the sun line.<br/> &copy; 2014 IEEE.
2014