#1National Aeronautics and Space Administration NASA's Photovoltaic Energy Research Plans and Programs Jeremiah McNatt Photovoltaic Technology Lead NASA Glenn Research Center [email protected] www.nasa.gov For Presentation at 3M on November 7, 2022 NASA#2National Aeronautics and Space Administration NASA Photovoltaic Needs and Goals General Needs for PV development programs: Increased cell efficiency, reduced cost, reduced weight, improved radiation tolerance NASA specific needs Higher power systems: Solar Electric Propulsion (Gateway, Mars Cargo), ISS, Human Landing System Power for Lunar and Mars Surface Missions (rovers, landers, power stations, site specific needs) including dust mitigation Unique environments with high radiation and/or intensity/temperature extremes Overall Goals of the GRC PV Group • Serve as an Independent verification/validation of PV technologies for other government agencies and industry Provide expertise to flight missions Build on interactions and collaborations with other government agencies www.nasa.gov#3National Aeronautics and Space Administration NASA State-of-the-Art Space Photovoltaics • Major US cell suppliers are SolAero Technologies and Spectrolab Nominally >30% in-space conversion efficiency • Gallium arsenide-based multijunction (3+ junction) solar cell technology Fully space-qualified to AIAA Standards Designed for End-of-Life (EOL) performance (within the space radiation environment) VERY EXPENSIVE (compared to terrestrial solar cells) • More "traditionally terrestrial" photovoltaic technologies are being seeing greater use www.nasa.gov#4National Aeronautics and Space Administration ● • ● Terrestrial PV Technology for Space Application of low-cost solar array blanket manufacturing methods and terrestrial solar cell technology for space missions • Automated manufacturing and modularity Use of silicon PV for short duration missions Focus is on "lower cost" cell technology NASA has conducted in-space flight experiments of terrestrial PV to evaluate long-term survivability under NASA mission requirements NASA Use of lower cost epitaxial grow techniques for gallium arsenide-based higher efficiency solar cells • Hydride Vapor Phase Epitaxy (HVPE) growth techniques being developed at National Renewable Energy Laboratory (NREL) Increased interest in perovskite solar cell technology • Potential for high efficiency terrestrial technology at lower fabrication costs www.nasa.gov ● Recent test results indicate potential for in-space radiation hardness#5National Aeronautics and Space Administration GRC PV Team NASA Civil Servant Jeremiah McNatt: PV Technology Lead Meghan Bush: Solar Cell Measurement/ Calibration Geoff Landis: PV Cell Technologies for Unique Missions Lyndsey McMillon-Brown: Perovskite and Thin Film PV, Optical Coatings AnnaMaria Pal: PV Cell Tech, Lunar Surface Solar Arrays Jeremiah Sims: Solar Cell Measurement Contractor Kaitlyn VanSant: Post Doc – Perovskite Technologies Boris Vayner: PV Cell/Array Arcing & Charging www.nasa.gov#6National Aeronautics and Space Administration ● NASA Project Scope Efforts span the NASA Technology Readiness Level (TRL) Scale Low TRL • NIAC - NASA Institute for Advanced Concepts NSTGRO - NASA Space Technology Graduate Student Research Opportunity Early Career Initiative / Center Innovation Fund Mid TRL SBIR - Small Business Innovative Research Environmental Testing High TRL • Flight Demonstrations Mission Support TRL 9 *Actual system "flight proven through successful mission operations TRL 8 •Actual system completed and "flight qualified" through test and demonstration (ground or space) TRL 7 •System prototype demonstration in a space environment TRL 6 •System/subsystem model or prototype demonstration in a relevant environment (ground or space) TRL 5 •Component and/or breadboard validation in relevant environment TRL 4 •Component and/or breadboard validation in laboratory environment TRL 3 •Analytical and experimental critical function and/or characteristic proof-of- concept TRL 2 •Technology concept and/or application formulated TRL 1 •Basic principles observed and reported www.nasa.gov#7National Aeronautics and Space Administration Graduate Student Program NASA Lower Cost / High Efficiency Cell Development 2 NASA Space Technology Graduate Research Opportunities (NSTGRO) at University of Illinois Urbana-Champagne with efforts focused on III-V materials on Si with improved radiation resistance Ryan Hool - Graduated in August 2022 • • Brian Li - Started as NSTGRO fellow in Fall 2019 Microcell CPV for Extreme Space Environments NSTGRO at Penn State developing a space-optimized system with a geometric concentration ratio of 30x that is ultra-compact (<600 μm thick) and capable of >350 W/kg at >33% power conversion efficiency under AMO Christian Ruud – Graduated August 2022 Laser Power Converters for Lunar Exploration NSTGRO at Rochester Institute of Technology growing and comparing lattice matched and metamorphic grade laser power converters. Katelynn Fleming - Started as NSTGRO fellow in Fall 2022 Call for New Proposals will be Released annually on https://nspires.nasaprs.com/ www.nasa.gov Looking for strong candidates (MS/PhD) developing space-related technologies (PV, batteries, fuel cells, PMAD)#8National Aeronautics and Space Administration Perovskite Solar Cells for Very Large Arrays: Space power at terrestrial costs Goal: Enable large area (>100kW), flexible thin film perovskite solar arrays on flexible substrates for lunar surface habitats. Strategy: Develop high efficiency, manufacturable, and durable space qualified perovskite solar arrays. Agency Need: Lunar surface power is unlike most other space power: the need is for very large areas, significantly reduced cost. These goals are more readily met by perovskite thin films than by SOA. A D Efficiency Manufacturability Durability B C NASA External Collaborators: Joseph M. Luther (NREL) – Perovskite Ink Development Sai Ghosh (UC-Merced) – Electrospray Perovskite Cells www.nasa.gov A) Design considerations schematic. B) Fabricated perovskite solar cell. C) MAPbl3 thin film integrated on MISSE-13. D) Artist rendering of in-space manufacture of perovskite solar cell NASA Point of Contact: Lyndsey McMillon-Brown ([email protected])#9National Aeronautics and Space Administration NASA Laser Power Beaming Use of laser to beam power to photovoltaic cell allows application of lightweight photovoltaic power to regions with no sunlight Particular application being developed is power for multiple rovers operating in permanently shadowed craters near the lunar poles NASA Glenn activities: GRC is technical lead for Space Technology Research Grant project with University of California Santa Barbara to develop and test laser power beaming as part of the Lunar Surface Technology Research (LUSTR) program Impact Technology could enable future rovers in permanently shadowed craters on the moon www.nasa.gov Laser power beaming for lunar polar power#10National Aeronautics and Space Administration NASA SBIR Programs GRC has supported the development of low/middle technology readiness level (TRL) photovoltaic devices, blankets, arrays, and testing equipment for many years through the Small Business Innovative Research (SBIR) program Work closely with Langley Research Center and the Jet Propulsion Lab to develop solicitations and manage SBIR programs Subtopics change every year but the need for in-space power is always there IGNITE Special Low Cost PV topic: https://sbir.nasa.gov/solicit-detail/80089 Proposals due on Sept 1, 2022 Can address any area of cost reduction, from substrate, to cell growth, to processing, to qual/testing at the blanket/array level. www.nasa.gov#11National Aeronautics and Space Administration • Ground Testing - High Altitude Measurement ER-2: High altitude (70k ft) experiment platform utilized for solar cell standard development Planned for a Fall Campaign. 2020 season was cancelled due to Covid-19. 2021 has been cancelled due to aircraft delays, looking for future aircraft availability 2nd flight pod built (not yet flown) to increase cell area per flight Collaborating with Blacksky Aerospace and Angstrom Designs on high altitude balloon testing Diagram 1 www.nasa.gov 809 Pod Mid Section - Source Measure Unit Data Aquisition Computer - Temperature Control System 44 Pod Aft Section - Collimation Tube - Spectrometer Enclosure NASA 27 11 14#12National Aeronautics and Space Administration Ground Testing - Solar Simulators NASA Solar Simulators • 3 zone - Spectrolab X25 based system Option for variable temperature chamber with quartz window 6 zone - Angstrom Designs LED based • Approximately 10" x 10" illumination area 5 zone - Angstrom Designs LED based large area pulsed solar simulator • Approximately 33" x 12" illumination area capability 17 total modules (reconfigurable to match string length) www.nasa.gov ESIGNS#13National Aeronautics and Space Administration NASA Advancement of Qualification Protocols for IMM-a NASA Space Technology Mission Directorate - Announcement of Collaboration Opportunity awarded to Maxar Technologies along with GRC and MSFC to test 5-junction solar cells through qualification protocols similar to AIAA S-111/112 to raise the TRL • Solar cell electrical performance testing capabilities at GRC Space environment testing facilities at MSFC Maxar is providing the SolAero IMM-a coupons Impact Enable future commercial and NASA missions with higher power at a lower mass • For small satellites more power can enable additional payload capabilities Smaller area footprint (W/m2) and higher specific power (W/kg). Driving metrics for solar arrays in space and on lunar surface Electrical Checkout and performance using LED- based pulsed solar simulator Sine vibe testing Thermal balance testing Electrostatic discharge testing UV radiation exposure Electron radiation exposure Proton radiation exposure Thermal cycling Sunt Leske High-Energy Accelerator Lab at MSFC (Electron and Proton Radiation Testing) www.nasa.gov#14www.nasa.gov National Aeronautics and Space Administration DMFlex - Dust Mitigation on Flexible Solar Arrays NASA NASA Space Technology Mission Directorate - Announcement of Collaboration Opportunity awarded to Maxar Technologies along with GRC to explore lunar dust mitigation methods for vertical, flexible solar arrays Investigating whether vibratory motion and/or electrostatic dust shielding effectively remove deposited lunar simulant on vertical arrays, verify using electroluminescence imaging + image processing Tests performed as a function of illumination, charging level, temperature and angle of solar array Rendition of a lunar lander with vertical solar arrays Regolith is notable for getting kicked up by surface activity and sticking to surfaces; could reduce solar array output 0e+00 G Frequency 2e+05 3e+05 4e+05 1e+05 A) Pristine Solar Cell D) 25 0.00 0.05 0.10 0.15 0.20 0.25 Histogram Gray Scale Pixels 0 5 10 15 20 20 Density Frequency 0e+00 1e+05 2e+05 Зе+05 4e+05 B) Dusted Solar Cell 20 0.00 0.05 0.10 0.15 0.20 0.25 Histogram Gray Scale Pixels 5 Density 55#15National Aeronautics and Space Administration Flight Test - MISSE 16 NASA Materials ISS Experiment (MISSE) MISSE 15, 6-month (planned) exposure to Low Earth Orbit (LEO) conditions launched in Aug 2021 MISSE 16, 6-month (planned) exposure to Low Earth Orbit (LEO) conditions planned launch July 2022 Includes lightweight, novel solar cells and modules (including Perovskites, Concentrators) Passive exposures similar to past ISS experiments in zenith direction A B Borosilicate DC-93-500 MAPI Borosilicate Control Flight 1 mm SPEED ALTITUDE 21 0.0 KM KM STAGE 1 TELEMETRY LIFT OFF о STARTUP MAX-Q T+00:00:04 CRS-25 NASA LIVE LIFTOFF THE HOLDDOWN CLAMPS HAVE RELEASED FALCON 9 AND WE HAVE BEGUN OUR FLIGHT & 13K www.nasa.gov Figure. A) MISSE on the ISS B) Schematic of perovskite active layer flown for 10 months in LEO on MISSE-13. C) Launch of MISSE-16#16National Aeronautics and Space Administration Solar Cell & Array Development - Outer Planets (LILT) NASA Extreme Environments Solar Power (EESP): Develop solar cell and array technologies for use in low intensity, low temperature (LILT) environments (beyond 5 AU) and high radiation environments in this region (Jupiter and its inner moons) Project Goal: 35% beginning of life (BOL) cell efficiency, 28% EOL efficiency at the blanket (or equivalent) level, measured at 5 AU and -125 °C; 8-10 W/kg measured at EOL, Packaging density at least 60 kW/m³ Project started in June 2016 with 4 contract Base Phase Awards, 2 later Option Phases led to 1 current award to Johns Hopkins Applied Physics Laboratory (APL) Flexible Array Concentrator Technology (DSS, APL) APL: Transformational Array (TA) System Concept Uses DSS Roll Out Solar Array (ROSA) for the array structure and blanket. Populated the array with high efficiency IMM solar cells which also offer longer life in radiation environments (SolAero IMM4 cell) Populated the array with concentrators to reduce array mass, volume, and cost and increase intensity on the cells by 2x. Current missions being planned to Jupiter's moon lo and to Neptune's moon Triton are considering including demonstrations of the Transformational Array. www.nasa.gov#17National Aeronautics and Space Administration Flight Test - EESP on DART Double Asteroid Redirection Test (DART) Mission: Launched November 24th, 2021 Opportunity existed for test of the APL Transformational Array cell and concentrator technology in similar flight configuration for near Earth mission The TA array technology will be placed on the portion of the array that provides power to the spacecraft The current from the TA strings and service strings will be measured using existing circuitry in the power system Data will be collected over the year long cruise to Didymos (Impacted on September 26, 2022) www.nasa.gov Qty=1 TFA SPM is on each wing/each IMBA blanket assembly -- Qty 1 TFA SPM sized to fit within the space of Qty 2 standard DART Spacecraft Segment SPM's Wing #1 IMBA blanket assembly TFA SPM location Asteroid Impact & Deflection Assessment \\AIDA NASA DART Double Asteroid Redirection Test Schematic of the DART mission shows the impact on the moonlet of asteroid (65803) Didymos#18National Aeronautics and Space Administration NASA ROSA Power Augmentation to ISS • 6 ROSA are being added to ISS to increase power production ROSA have been installed (June 2021) Each new solar array is ~20 kilowatts (total ~120 kilowatts) New arrays do partially shadow current arrays Remaining uncovered solar arrays and partially uncovered original arrays will continue to generate ~95 kilowatts of power New total for ISS ~215 kilowatts (215,000 watts) from ~160 kW previously www.nasa.gov#19National Aeronautics and Space Administration Solar Array Development - Lunar Orbit NASA PV Systems will be used to power many near-term lunar missions Gateway Power and Propulsion Element (PPE) will be powered by 2 ROSA solar arrays (50 kW class) Human Landing System (HLS) includes elements of photovoltaics www.nasa.gov#20National Aeronautics and Space Administration Vertical Solar Array Structures (VSAT) www.nasa.gov NASA#21National Aeronautics and Space Administration VSAT Program Overview ● Vertical Solar Array Technology (VSAT) for Lunar Surface NASA STMD Game Changing Development program Led by NASA Langley and NASA Glenn (Richard Pappa/LaRC and AnnaMaria Pal/GRC) Autonomous deployment, 10kW class systems 10 meter minimum height at bottom of the array Stable on steep terrain (adaptable to deploy vertically on slanted terrain up to 15 degrees) Resistant to abrasive lunar dust Minimized both mass and packaged volume for ease in delivery to the lunar surface www.nasa.gov NASA#22National Aeronautics and Space Administration Motivation Lunar polar locations are of high interest for many NASA missions due to potential for ice and materials in permanently shadowed craters W Moon's rotation is slow, approximately 1 rotation every 29.5 Earth days Moon's equatorial plane is tilted by only 1.5° Locations exist that can have long durations of illumination with minimum shadowing (down to <100 hours) at high elevations www.nasa.gov S At exactly the South Pole, -90° S latitude Mid Summer (+1.5 deg above horizon) (-1.5 deg below horizon) E Mid Winter W N 옷 ヨ -90° - X° NASA In general, at -X° S latitude, Sun paths tilt up by 90° - X° For example, at -88° S latitude, Sun paths tilt up by 2°#23National Aeronautics and Space Administration www.nasa.gov Motivation Sun Paths at an Elevated Site Near the South Pole (Movie) At Mid-Summer At Mid-Winter video shows 1 full lunar day Provided by James Fincannon, GRC NASA#24National Aeronautics and Space Administration NASA Initial (Base) Phase Base period contracts, valued at up to $700,000 each, awarded as 12 - month fixed price contracts to: Astrobotic Technology, Pittsburgh, PA Northrop Grumman (ATK), Goleta, CA Honeybee Robotics, Brooklyn, NY Lockheed Martin, Littleton, CO Maxar Technologies, Palo Alto, CA Contracts started in Spring 2021 to further system design, perform initial testing and modeling and prepare plans for Option Phase which includes scaled hardware testing Plan was to down select up to two companies and provide additional funding, up to $7.5 million each, to build prototypes and perform environmental testing www.nasa.gov#25National Aeronautics and Space Administration Option Phase Option Phase Award was announced on August 23, 2022. https://www.nasa.gov/press- release/three-companies-to-help-nasa-advance-solar-array-technology-for-moon 3 Companies selected to go forward to build hardware for environmental testing •Astrobotic Technology of Pittsburgh, Pennsylvania: $6.2 million •Honeybee Robotics of Brooklyn, New York: $7 million •Lockheed Martin of Littleton, Colorado: $6.2 million Projects will start soon with thermal vacuum testing planned for early 2024 www.nasa.gov NASA#26National Aeronautics and Space Administration Photovoltaic Investigation on the Lunar Surface (PILS) - PV Testbed for Lunar Landers www.nasa.gov 0 NASA ୨-ଅଧns avnn PILS TAIC INVESTIGATION ON THE#27National Aeronautics and Space Administration NASA Background Photovoltaics and solar arrays have provided reliable power to spacecraft for over 50 years and will enable long duration missions on the lunar surface Solar cells have been used on the lunar surface in the past but the technology has matured significantly There is still a lot unknown about the energized environment of the lunar surface and how it would impact high voltage solar arrays The Commercial Lunar Payload Services (CLPS) program supports Artemis with commercial deliveries to perform science experiments, test technologies and demonstrate capabilities to help NASA explore the Moon and prepare for human missions Many of the CLPS providers plan to use photovoltaics to power their spacecraft Solar arrays on the Apollo 11 Seismic Experiment www.nasa.gov#28National Aeronautics and Space Administration Background PILS team responded to a CLPS program call in late 2019 to provide readily available (requiring minimal tech development) payload packages for integration onto future landers The team proposed a photovoltaic test-bed to measure electrical performance of state of the art and next generation solar cells, and to measure the charge build up on a small solar cell array The concept was based off a heritage Materials on the International Space Station Experiment (MISSE) solar cell flight test platform Individual cells Honeycomb FRONT SIDE -Solar cell strings MUX subassembly- CPU subassembly -Arc IV subassembly subassembly High voltage subassembly REAR SIDE Selected by Astrobotic, which will launch its Peregrine lander on a United Launch Alliance Vulcan Centaur rocket, along with 10 other NASA payloads Landing at Lacus Mortis for a lunar day long mission (approx. 10 Earth days) www.nasa.gov Prior ISS Solar Cell Experiment Lacus Mortis circled in Red NASA#29National Aeronautics and Space Administration Mission Objectives Technical Objectives Successfully deliver flight hardware to Astrobotic for integration onto the Peregrine Lander Do not exceed mass, power, size restraints Do no hard to the lander or other payloads Increase the TRL of solar cells and measure charge accumulation on an array of solar cells Science Objectives NASA Science objective 1: Determine performance and health checking of SOA and Next gen solar cells and terrestrial silicon cells over a lunar day. Perform I-V and temperature measurements for each cell regularly throughout mission The cells are not under load ("powered" or "powering anything") when not scanning an I-V curve Science objective 2: Measure the localized charging environment on a small solar array by collection of charge deposited on solar cell cover glass Charging environment influenced by local neutral plasma. Bonus: get data in transit to the moon www.nasa.gov#30National Aeronautics and Space Administration NASA Design Concept and Requirements Dimensions: 30 x 30 x 4cm (without mounting brackets) Designed to be mounted in multiple configurations (through bracketry) based on landing site and lander design Capped mass at 4.5 kg Requires approximately 2W for solar cell and charging experiment. Designed to use additional power for heaters during cruise phase Team designed PILS platform to accommodate interfaces with the Peregrine lander in terms of power, communication, mounting, environmental concerns Early rendering of Peregrine www.nasa.gov PILS Mock Up Based on Initial Concept Rendering of PILS mounted on an early Peregrine design#31National Aeronautics and Space Administration Design Considerations - Lessons Learned Initial concept used solar cell high altitude flight calibration holders but they added significant mass. Found a solution to use a single circuit board type top surface to mount the solar cells NASA During early design the launch loads were not well known which presented a challenge to design the platform to be lightweight but still robust. Multiple iterations were considered and modeled to get to the final design. The thermal environment turned out to be our largest environmental driver. Challenge to keep the electronics warm during transit to the moon and to keep them cool while on the surface during the lunar day. Found solutions with multilayer insulation and thermal tape. Built scaled mock-ups of the platform to better understand interfaces and clearances 69060 Heat Load PILS Thermal Analysis Model www.nasa.gov Mises) Stress-Top/Bottom 13 HH HH HH PILS Structural Analysis Model PILS Platform High Fidelity Mock Up#32National Aeronautics and Space Administration NASA • • Solar Cell Manifest (1) 4x8 cm SolAero Z4J, triple junction III-V (1) 4x8 cm SpectroLab XTJ prime, triple junction III-V (2) 4x8 cm SpectroLab XTE-SF triple junction III-V (2) 4x9 cm SolAero IMM alpha 5 junction III-V (2) 2x2 cm ASU Silicon Heterojunction Intrinsic Thin Film (HIT) (8) 2x2 cm Spectrolab UTJ triple junction III-V with ITO coated connected coverglass for Surface Charge Experiment 000000 000000 000000 000000 XTE poooooo 000000 000000 000000 IHH UTJ HH XTE Si Si IMM-a XTJ Z4J IMM-a Surface Charge Experiment HAVE YOURSELF A PILS e 19380304 YOU'VE EARNED IT 2x2cm UTJ solar cells strung in series and shorted through a burden resistor which sets a bias potential from OV to 18V Maximum current is approximately 100mA, not enough for secondary arcing under any voltage. Solar cell coverglass coated with <100kOhm/sq ITO to bleed charge, but the charge is isolated by high dielectric constant encapsulant Wires are soldered to coverglass to short all surfaces and connect to large series resistor Back-end of resistor to be fed to plasma monitoring measurement board www.nasa.gov#33National Aeronautics and Space Administration Finalizing Design Astrobotic made a configuration change to the lander, adding walls to two sides PILS was now cantilevered off the wall and exposed to additional thermal conditions from the lunar surface Software and hardware designs were locked, build and assembly began Benchtop testing with Astrobotic payload simulator occurred Environmental testing occurred (thermal, vibe, EMI) www.nasa.gov Software/Hardware Checkout HAVE YOURSELF A PILS S YOU'VE EARNED IT XXXXXX ASTROBOTIC NASA Assembled PILS Flight Unit Assembled PILS Flight Unit with Thermal Tape Applied to Top Surface