Parker Solar Probe Bibliography

2017

The Solar Probe Plus (SPP) mission plans to launch a spacecraft to explore the Sun in 2018. Attitude control is maintained with a 3-axis stabilized, closed-loop control system. One of the first tasks for this system is acquiring attitude knowledge and establishing attitude control after separation from the launch vehicle. Once control is established, the spacecraft must be moved through a sequence of attitudes to meet power and thermal constraints and reach a powerpositive state. This paper describes the options selected for the sequence of initial attitudes and gives results for expected performance for nominal and contingency timelines after separation.<br/>
2017


As the Solar Probe Plus (SPP) program moves into the flight hardware build phase, the final testing of the qualification panel has been completed. The rigorous testing is many orders of magnitude more intensive than that used for standard earth-orbit missions. Testing under high irradiance, high temperature conditions over large areas poses design and logistic challenges, which have spurred innovation in steady state illumination. New test hardware of interest include a large area LED simulator capable of 6X AM0 string currents while the panel is under vacuum, along with an LED light source to supply greater than 22X AM0 string currents while the panel is at atmosphere. In addition, silicone degradation comparison via LED and broadband light sources is presented, along with a novel method to improve the EOL performance of the SPP solar arrays through pre-flight ultraviolet illuminated outgassing.<br/> &copy; 2017 IEEE.
2017


Solar Probe Plus (SPP) is a NASA mission that will go within ten Solar Radii of the sun. One of the crucial technologies in this system is the Thermal Protection System (TPS), which shields the spacecraft from the sun. The TPS is made up of carbon-foam sandwiched between two carbon-carbon panels, and is approximately eight feet in diameter and 4.5 inches thick. At its closest approach, the front surface of the TPS is expected to reach 1200&deg;C, but the foam will dissipate the heat so the back surface will only be about 300&deg;C. Solar Probe Plus is scheduled to launch in 2018, and the program is in the beginning stages of integration and testing. As part of the testing process, SPP s cooling system and the full spacecraft will undergo thermal tests. Radiation from the back of the TPS plays a large part in both of these systems thermal environment. To get the back surface of the TPS to 300&deg;C, large amounts of energy needs to be put into the top of the TPS. However,…
2017


The Frontier Radio for the Solar Probe Plus mission offers a host of hardware design and manufacturing improvements. These improvements build on the technology readiness level (TRL)-9 radio platform that was flown on the Van Allen Probes mission in a duplexed S-band configuration and several development tasks funded by NASA Headquarters. Prior RF slice designs consisted of two separate circuit boards: one for lower frequencies and one for high-frequencies; advances in technology enabled the use of a high-frequency multilayer laminate with highly integrated miniature components to create a single circuit board, thereby simplifying manufacturing. This change also enabled an improved circuit topology in the upconverter in both exciters producing lower phase noise and better I/Q modulation accuracy. RF shielding performance was improved using compartmentalized plates and Spira-Shield gaskets. Use of a magnesium alloy for the slice packaging reduced the overall radio mass. A design-variant…
2017


NASA s Parker Solar Probe (PSP) spacecraft (formerly Solar Probe Plus) is scheduled for launch in July 2018 with a planned heliocentric orbit that will carry it on a series of close passes by the Sun with perihelion distances that eventually will get below 10 solar radii. Among other in-situ and imaging sensors, the PSP payload includes the two-instrument "Integrated Science Investigation of the Sun" suite, which will make coordinated measurements of energetic ions and electrons. The high-energy instrument (EPI-Hi), operating in the MeV energy range, consists of three detector-telescopes using silicon solid-state sensors for measuring composition, energy spectra, angular distributions, and time structure in solar energetic particle events. The expected performance of this instrument has been studied using accelerator calibrations, radioactive-source tests, and simulations. We present the EPI-Hi measurement capabilities drawing on these calibration data and simulation results…
2017


The Johns Hopkins University Applied Physics Lab (JHU/APL) has developed a flight qualified, hermetically sealed, I/Q modulator Ka-band Multi-chip Module (MCM). Prototypes of this device have been developed over the years, but Solar Probe Plus (SPP) will be the first mission to use a flight qualified version of the MCM. This MCM enables a first for a deep-space mission: primary science data downlink with simultaneous data and navigation over Ka-band. SPP will also be the first JHU/APL mission to use Ka-band for downlink. The MCM contains three gallium arsenide (GaAs) monolithic microwave integrated circuit (MMIC) die, two of which are commercial off the shelf (COTS) parts, and the third is a custom die designed at JHU/APL. The MCM takes an X-band input, multiplies the signal up to Ka-band, modulates I/Q data directly onto the Ka-band carrier and outputs a signal in the +10dBm range, capable of driving an external SSPA or TWTA. Improvements made over previous prototype designs include…
2017


In 2012, The Johns Hopkins Applied Physics Laboratory (APL) was approved by the National Aeronautics and Space Administration (NASA) to move forward with Phase B of the Solar Probe Plus (SPP) Mission to design and build the first spacecraft to fly into the Sun s outer atmosphere and study its effects on planetary systems and human activities. While APL had successfully utilized its earned value management system (EVMS) on the Van Allen Probes mission, the SPP contract called for a "certified" EVMS, which required an in-depth government compliance review, validation, and approval. Historically, government agencies and contractors were dependent on the availability of the Defense Contract Management Agency (DCMA) to conduct EVMS compliance reviews, but in June 2013 NASA decided to perform the reviews in lieu of DCMA. This review was formally conducted May 11-15, 2015. This paper details the cost and schedule tools, methods, and processes APL used to satisfy the 32 guide lines…
2017


To assure mission success of the Solar Probe Plus (SPP) spacecraft, defined by achieving its final mission orbit with a perihelion distance of less than 10 solar radii, 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. Recently, we presented an experimentally validated approach being developed at the Johns Hopkins University Applied Physics Laboratory (JHU/APL) for designing and analyzing MLI to meet this challenge. This paper extends the results to Whipple shield configurations consisting of an MLI bumper, 0-1&prime; standoff, and an Aluminum honeycomb rear wall. With 0&prime; MLI-honeycomb standoff, 0.05 g/cm<sup>2</sup> MLI layered in a manner similar to that found in actual blankets and an Aluminum honeycomb consisting of 8 mil-thk. facesheets, 0.125&prime;-dia. cells and 1<sup>…
2017


Solar Probe Plus (SPP) is a NASA mission developed to visit and study the sun closer than ever before. SPP is designed to orbit as close as 7 million km (9.86 solar radii) from Sun center. One of its instruments: WISPR (Wide-Field Imager for Solar Probe Plus) will be the first local imager to provide the relation between the large-scale corona and the in-situ measurements.<br/> &copy; 2017 SPIE.
2017


The Solar Probe Plus (SPP) mission, part of NASA s Living With a Star program, is set to launch in July of 2018 on a trip to travel through the Sun s corona. The first component that will be integrated to the spacecraft is the Power Distribution Unit (PDU). The SPP PDU was based on the PDU design utilized for the Van Allen Probes (formerly Radiation Belt Storm Probes) mission, but with some very significant differences. Due to the fact that the SPP spacecraft is a much more complex vehicle, it requires nearly twice as many power services as the Van Allen mission which resulted in a PDU twice the size. Also, the Van Allen PDU utilized a single non-redundant Inter-Integrated Circuit (I2C) bus and command/telemetry interface (since the PDU redundancy was considered to be built into the dual spacecraft design) and the SPP PDU utilizes a dual redundant E2C bus along with 2 separate command and telemetry interfaces. Additionally, the command and telemetry Interface (I/F) paradigm between…
2017


2016

<p>We analyze the heavy ion components (A \&gt;4 amu ) in collisionally young solar wind plasma and show that there is a clear, stable dependence of temperature on mass, probably reflecting the conditions in the solar corona. We consider both linear and power law forms for the dependence and find that a simple linear fit of the form T<sub>i</sub>/T<sub>p</sub>=(1.35 \textpm.02 )m<sub>i</sub>/m<sub>p</sub> describes the observations twice as well as the equivalent best fit power law of the form T<sub>i</sub>/T<sub>p</sub>=(m<sup><sub>i</sub>/m<sub>p</sub>) 1.07 \textpm.01</sup> . Most importantly we find that current model predictions based on turbulent transport and kinetic dissipation are in agreement with observed nonthermal heating in intermediate collisional age plasma for m /q \&lt;3.5 , but are not in quantitative or qualitative agreement with the lowest…
2016


<p>The first in situ measurements of electric and magnetic fields in the near-Sun environment (\&lt; 0.25 AU from the Sun) will be made by the FIELDS instrument suite on the Solar Probe Plus mission. The Digital Fields Board (DFB) is an electronics board within FIELDS that performs analog and digital signal processing, as well as digitization, for signals between DC and 60 kHz from five voltage sensors and four search coil magnetometer channels. These nine input signals are processed on the DFB into 26 analog data streams. A specialized application-specific integrated circuit performs analog to digital conversion on all 26 analog channels simultaneously. The DFB then processes the digital data using a field programmable gate array (FPGA), generating a variety of data products, including digitally filtered continuous waveforms, high-rate burst capture waveforms, power spectra, cross spectra, band-pass filter data, and several ancillary products. While the data products are…
2016


<p>Solar Probe Plus (SPP) will be the first spacecraft to fly into the low solar corona. SPP\textquoterights main science goal is to determine the structure and dynamics of the Sun\textquoterights coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. Understanding these fundamental phenomena has been a top-priority science goal for over five decades, dating back to the 1958 Simpson Committee Report. The scale and concept of such a mission has been revised at intervals since that time, yet the core has always been a close encounter with the Sun. The mission design and the technology and engineering developments enable SPP to meet its science objectives to: (1) Trace the flow of energy that heats and accelerates the solar corona and solar wind; (2) Determine the structure and dynamics of the plasma and magnetic fields at the sources of the solar wind; and (3) Explore mechanisms that…
2016


<p>Simple estimates of the number of Coulomb collisions experienced by the interplanetary plasma to the point of observation, I.e., the \textquotedblleftcollisional age\textquotedblright, can be usefully employed in the study of non-thermal features of the solar wind. Usually these estimates are based on local plasma properties at the point of observation. Here we improve the method of estimation of the collisional age by employing solutions obtained from global three-dimensional magnetohydrodynamics simulations. This enables evaluation of the complete analytical expression for the collisional age without using approximations. The improved estimation of the collisional timescale is compared with turbulence and expansion timescales to assess the relative importance of collisions. The collisional age computed using the approximate formula employed in previous work is compared with the improved simulation-based calculations to examine the validity of the simplified formula. We also…
2016


The Solar Probe Plus (SPP) mission, under NASA s Living with a Star program, will fly a spacecraft (S/C) through the sun s outer corona. The mission will gather data on the processes of coronal heating, solar wind acceleration, and production, evolution and transport of solar energetic particles. The spacecraft has an Electrical Power System or EPS that has to undergo testing before delivery to the spacecraft for integration and testing. The specific unit to be delivered is called the Power System Electronic box or PSE. The PSE relies on a novel S/A control algorithm which autonomously positions the wings to optimize the thermal load while maintaining adequate electrical power. A Wrap Around Automated Testbed (WAAT) containing various Ground Support Equipment (GSE) has been designed to test the PSE in real-time. The major components of the Testbed consist of a dynamic solar array simulator (SAS); A Battery Simulator to emulate the spacecraft flight battery; An EPS emulator to control…
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


The NASA&rsquo;s Solar Probe Plus spacecraft must endure extreme heat loads while passing near the Sun. Due to its high incident heatload and temperature, the spacecraft Thermal Protection System (TPS) must be simulated using a custom thermal simulator during spacecraft thermal vacuum testing. As part of the development of the TPS thermal simulator, subscale testing was performed. The design, testing, results and lessons learned are described in this paper. Especially useful are the design aspects needed to achieve the high temperatures, low spatial gradients, and strict contamination requirements required by the program. Following successful subscale testing, the program is moving forward to the fabrication and test of the full scale simulator.<br/> &copy; 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
2016


The Solar Probe Plus (SPP) mission is preparing to launch in 2018, and will directly investigate the outer atmosphere of our star. At 9. 86 solar radii, SPP must operate in an unexplored regime. The environment and aspects of the mission design present some unique challenges for navigation, particularly in terms of modeling the dynamics. Non-gravitational force models, unique to this mission, are given with analytical expressions. For each of these models (and error sources), a maximum bound on the force perturbation magnitude is quantified numerically. Additionally, the effect of charged particles on ra-diometric observables is discussed, along with methods being employed to pre-process the measurements. This survey is an overview of unique modeling employed by SPP navigation, but also a reference for future missions traveling near the Sun.<br/> &copy; 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.
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


As the Solar Probe Plus (SPP) program moves into the flight hardware build phase, the final testing of the qualification panel has been completed. The rigorous testing is many orders of magnitude more intensive than that used for standard earth-orbit missions. Testing under high irradiance, high temperature conditions over large areas poses design and logistic challenges, which have spurred innovation in steady state illumination. New test hardware of interest include a large area LED simulator capable of 6X AM0 string currents while the panel is under vacuum, along with an LED light source to supply greater than 22X AM0 string currents while the panel is at atmosphere. In addition, silicone degradation comparison via LED and broadband light sources is presented, along with a novel method to improve the EOL performance of the SPP solar arrays through pre-flight ultraviolet illuminated outgassing.<br/> &copy; 2016 IEEE.
2016


The Solar Probe Plus 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, and evolution and transport of solar energetic particles. The S/C is powered by two actively cooled photovoltaic solar array (S/A) wings. A novel power system electronics (PSE) box facilitates power delivery to the S/C in a tightly packaged, single-fault-tolerant system. The PSE contains a central digital controller to maximize power throughput from the S/A while protecting the battery, S/A, and downstream loads. The PSE is configurable and scalable up to 900-W output power. A novel grounding and isolation scheme is presented with the detailed architecture and digital control implementation.<br/> &copy; 2016, American…
2016


Radio receivers for deep space telecommunications require tracking loops that are robust in low signal-to-noise ratio conditions for not only carrier tracking, but also subcarrier tracking and bit synchronization. However, the loop band-widths must not be too narrow so as to accommodate Doppler dynamics, oscillator drift, and requirements for expedient and reliable data acquisition. The present work describes the data acquisition performance of Frontier Radio for the NASA Solar Probe Plus mission. The data acquisition time is a statistical quantity, as it depends on the frequency and phase state of the uplink waveform which is random with respect to the receiver. In order to rigorously characterize the performance and determine a nominal worst-case acquisition time, an automated test procedure was developed to execute a large number of acquisition trials. By architecting an automated procedure for the remote control of instruments, including timing control and uplink signal phase…
2016


The latest adaptation of the Frontier Radio, an X/Ka-band deep space implementation, has been transitioned into a finished product for Solar Probe Plus (SPP) and future missions. Leveraging the technology readiness level (TRL) 9 software-defined radio (SDR) platform successfully flown on the Van Allen Probes (VAP) mission, the Frontier Radio now brings a low-power, low-mass, yet highly radiation-tolerant and robust SDR to deep space applications. This implementation brings with it a suite of enhanced capabilities and improvements to the Frontier Radio platform. The core deep space software implementation is designed to match or improve upon the signal acquisition and tracking performance, as well as improve the receive and transmit implementation losses of its predecessors (JHU/APL and industry). The deep space radio operates using less than 6W at 30V in receive mode, and approximately 10W with either the X- or Ka-band exciter enabled and operating in two-way coherent duplex mode. The…
2016


Comprehensive Spacecraft Flight Software requirements verification is essential to the success of deep space missions. NASA s Solar Probe Plus (SPP) Spacecraft Flight Software and requirement verification activities are being implemented by Johns Hopkins University Applied Physics Laboratory (JHU/APL) located in Laurel, MD. JHU/APL s software development process for a critical mission requires an independent verification of all Spacecraft Flight Software requirements. The complexity of SPP s Spacecraft Flight Software and the number of critical requirements mandates an efficient process to build, maintain and execute a comprehensive test suite. In addition, detailed reports must contain relevant information on test execution steps for post-execution analysis verification and for test artifact dissemination to external reviewers (NASA Independent Verification and Validation). The Van Allen Probes mission (launched in 2012) implemented the initial Test Framework currently being used to…
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


New technologies are constantly being developed at many space-related institutions. A significant challenge is to not only propose and develop these new technologies, but to infuse them into real space missions. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) has a successful history of infusing such new technologies into NASA flight programs, including non-coherent navigation in the CONTOUR mission (launched 2002), a circularly-polarized phased-array antenna on the MESSENGER mission (2004), and a low-power receiver on the New Horizons mission (2006). Over the last several years, JHU/APL has developed a new line of software-defined radio, the Frontier Radio, to be used on flight missions. The Near-Earth version of this radio (Frontier NE), operating at S-band, is flying on the NASA Van Allen Probes (VAP) mission (launched in 2012). Subsequent Deep-Space versions of this radio (Frontier DS) are baselined for the NASA Solar Probe Plus Mission (launch 2018) and the…
2016