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HOTTech Program Status UpdateVEXAG Meeting - November 16, 2020

Program Officer: Quang-Viet Nguyen, Ph.D.

Planetary Exploration Science Technology Office Manager: Carolyn Mercer, Ph.D.

Venus Technology Lead: Adriana Ocampo, Ph.D.

Planetary Science Division

NASA Headquarters, Washington, DC

• HOTTech is a ROSES-2016 Announcement of Opportunity from the Planetary Science

Division, Science Mission Directorate, NASA Headquarters

• The primary science objective was to develop and mature technologies that will enable,

significantly enhance, or reduce technical risk for in situ missions to high-

temperature environments with temperatures approaching 500ºC or higher for the robotic

exploration of high-temperature environments such as the Venus surface, Mercury, or the

deep atmosphere of Gas Giants.

• HOTTech is aimed at the development of high temperature electrical, electronics, electro-

mechanical systems that could be needed for potentially extended in situ missions to

such environments. HOTTech is not meant for instrument development

• 12 proposals were awarded (circa $600k to $700k) for 2-3 years. Program is coming to a

close but the Integrated Testing aspect remains to be done.

High Operating Temperature Technology (HOTTech) Program Overview

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TechnologyArea HOTTech Tasks PI Organization

Packaging 500°C Capable, Weather-Resistant Electronics Packaging for Extreme Environment Exploration

Alan Mantooth

University of Arkansas

Clocks &Oscillators

Passively Compensated Low-Power Chip-Scale Clocks for WirelessCommunication in Harsh Environments

DebbieSenesky

StanfordUniversity

GaNElectronics High Temperature GaN Microprocessor for Space Applications Yuji Zhao Arizona State

UniversityComputerMemory High Temperature Memory Electronics for Long-Lived Venus Missions Phil

Neudeck NASA GRC

DiamondElectronics High Temperature Diamond Electronics for Actuators and Sensors Bob

NemanichArizona State

UniversityVacuum

ElectronicsField Emission Vacuum Electronic Devices for Operation above 500 degreesCelsius

LeoraPeltz Boeing Corp.

ASICs & Sensors

SiC Electronics To Enable Long-Lived Chemical Sensor Measurements at the VenusSurface

Darby Makel MakelEngineering,

IncPrimaryBatteries

High Temperature-resilient And Long-Life (HiTALL) Primary Batteries forVenus and Mercury Surface Missions

RatnakumarBugga NASA JPL

RechargeableBatteries

High Energy, Long Cycle Life, and Extreme Temperature Lithium-SulfurBattery for Venus Missions

JitendraKumar

University ofDayton

Solar Power Low Intensity High Temperature (LIHT) Solar Cells for Venus ExplorationMission

JonathanGrandidier NASA JPL

Power Generation

Hot Operating Temperature Lithium combustion IN situ Energy and Power System (HOTLINE Power System)

Michael PaulJHU/APL

Electric Motors Development of a TRL6 Electric Motor and Position Sensor for Venus

Kris Zacny Honeybee Robotics, Inc.

HOTTech-1 Project Technology Areas

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5

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How Technology Areas Map to Spacecraft Systems

SPACECRAFT BUS

Mechanical Structures

Materials

Propulsion

Thermal Control

5, 6

COMMUNICATIONS High Power RF Amplifiers

Antennas & Pointing

1Packaging

8PrimaryBattery

9Rechargeable

Battery10

Solar Power

77

7

5Power Control

Electronics

4

11Power Generation

12Actuators/Motors

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Optoelectronics & Cameras

2, 5, 6

3, 5, 6

POWER SYSTEMS

A Snapshot of HOTTech

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Photovoltaic operation in the lower atmosphere and at thesurface of VenusJonathan Grandidier, Alexander P. Kirk, Phillip Jahelka,Margaret A. Stevens, Pawan K. Gogna, David Crisp, Mark L. Osowski, Thomas E. Vandervelde,

Harry A. Atwater, James A. Cutts

Double-junction GaInP/GaAs solar cells may be able to operate and survive for several weeks on the 465°C Venus surface

• 4 weeks of exposure at 465 °C yielded no degradation• Fill factor reduced after 7 weeks exposure• Encapsulation needed to protect against corrosive

atmosphere

High Temperature Operating Technologies (HOTTech)

Objective: Fabricate a solar cell that can operate at 300C and 21 km altitude and survive at the surface of Venus.

Highlights:(1) Fabrication of LIHT solar cells.(2) Device modeling of LIHT solar cells at various altitudes of the Venus atmosphere.(3) Demonstration of LIHT solar cells with 16% efficiency at 300C under a simulated 21 km altitude Venus solar spectrum.(4) Survive at 465C Venus surface temperature for more than 1 month.(5) Photovoltaics operation at the surface of Venus.

Publications:

Simplified cross-section schematic of a GaInP/GaAs 2J solar cell designed for high temperature operation.

I-V response (AM0 spectrum) from a Gen 2 GaInP/GaAs 2J solar cell with high temperature grid metal before and after heating at 465°C for up to 7 week.

Low Intensity High Temperature (LIHT) Solar Cells for Venus Exploration Missions

J. Grandidier, A. P. Kirk, M. L. Osowski, P. K. Gogna, S. Fan, M. L. Lee, et al., “Low-Intensity High-Temperature (LIHT) Solar Cells for Venus Atmosphere,” IEEE Journal of Photovoltaics, vol. 8, pp. 1621-1626, 2018.

J. Grandidier, A. P. Kirk, P. Jahelka, et al., “Photovoltaic Operation in the Lower Atmosphere and at the Surface of Venus,” Wiley Progress in Photovoltaics, vol. 28, pp. 545-553 (2019).

PI: J. Grandidier, JPL

SiC Electronics to Enable Long-Lived Chemical Sensor Measurements at the Venus Surface

PI: Darby Makel/Makel Engineering, Inc.

Co-PIs:

Results:

Significance:

Background:

High Temperature Operating Technologies

• SiC electronics will enable uncooled, long-lived operation of advanced chemical sensors for trace species including SOx, CO, OSC, HF, HCl, H2O, NO, H2, O2 at 500oC.

• Such capabilities will allow extended characterization of the Venus atmosphere down to the surface.

• Compact, lightweight chemical sensor array could be integrated into probes and lander concepts

Kevin Baines, Ashley Davies,/Jet Propulsion LaboratoryGary Hunter/NASA Glenn Research Center

• SiC ASIC designs for signal conditioning and closed loop heater control completed by NASA GRC and MEI. ASICs fabricated as part of previous GRC SiC processing run and operation of amperometric and potentiometric chemical sensors has been verified at 500C.

• Compact 2”x4” functionally complete six channel chemical sensor (SOx, CO, OCS, HF,NO, HCl) array with SiC electronics fabricated and is ready for testing at GEER.

• The system is compatible with LLISSE system electronics which included A/D and communication capabilities.

• Enhanced version of ASIC designs are in fabrication with the latest GRC SiC electronics processing run.

• Progress on integrated SiC electronics and high temperature chemical sensor arrays is rapidly maturing to be ready for near term Venus mission opportunities and technology demonstrations.

• Simple, compact system is a key component for obtaining important science data.

• System is compatible with the LLISSE SiC electronics architecture and could be used on other platforms as well

• Planning in progress for 2021 terrestrial demonstration at volcanic/geothermal test site.

• Dual use applications include high temperature embedded instrumentation for propulsion and energy systems.

ASIC Circuit Substrate Design Initial Concept With

Chemical Sensors

Six Channel Chemical Sensor Array with SiC Electronics

PI: R. V. Bugga, JPLHigh Temperature Batteries for Venus Surface Missions

• Develop an enabling battery for Venus surface missions, (30 d at 475oC (and 92 bar).

• LISSE (NASA GRC Lander) goal: 60 daysPrevious Venus surface missions lasted <2 h.

• Anode (Li alloys, e.g., Li-Al, Li-Si)• Cathodes

• Metal Sulfides: FeS, FeS2, CoS2, NiS2, TiS2• Metal Phosphorous Trisulfides: FePS3, NiPS3

• Molten salt electrolyte (mixed alkali metal halides)• LiCl-KCl (44 wt% LiCl and 56 wt% KCl) (m.p.359oC)

• Separators (MgO, Al2O3, Li2O)

• Improve chemistry (for 60 day operation).

• 50% improvement with cathode coating

• New electrolytes and cathode materials

• High pressure design• Bipolar cell stack• GEER Testing of cells

and batteries• Battery qualification in

Venus environments.

Battery Chemistry

• Cells fabricated with JPL recipe and materials

• Leverage EaglePicher’s expertise in thermal batteries

475oC

Prototype CellsPrototype Cells

Path Towards Infusion

Goal and Objective

Enhances Venus probe missions

• Poor cathode utilization at low discharge rates due to cathode dissolution in electrolyte.

• Electrolyte formulation developed to extend cell lifetime; Demonstrated >20 days of operation in laboratory cells at 475oC

• Low electrolyte and high binder content reduce self discharge.

Electrolyte optimization at C/20 discharge

Components

D. Glass, J. P. Jones, A. Shevade, D. Bhakta, E. Raub, R. Sim and R. V. Bugga, J. Power Sources, 449 (2020) 227492;

~100 days of operation with recharge

Prototype Cells

Li(Al)-FeS Laboratory cells @ 475oC

High Temperature Memory Electronics for Long-Lived Venus MissionsPI: Phil Neudeck/NASA Glenn Research Center

Target: Demonstrate high temperature memory circuits,Random Access Memory (RAM) and Read Only Memory (ROM),operable for extended periods in Venus environments.

Science:• Complements on-going high temperature electronics

development towards realization of a long-lived Venus surface science station by providing unique memory capabilities that notably change possible mission architectures.

• Core electronics and packaging previously demonstrated for 60 days in simulated Venus surface conditions; Near 1000°C temperature span also demonstrated

Objectives:• Develop fully functional 500°C memory packaged circuits

operating in-situ for long duration Venus missions composed ofboth RAM (with read/write capability) and ROM (Read OnlyMemory) chips capable of interfacing with mission control logicand sensors.

• Demonstrate both circuit types with Venus representativedata storage in laboratory conditions (at least 3 months) andin simulated Venus environments (GEER) (60 days).

Highlights Include:1.First fabrication and Demonstration of Long-Duration High Temperature Memory2.RAM and ROM prototypes have both been completed, with more complex circuits designed and in fabrication3.GEER testing planned as part of HOTTech project

Long-Term RAM Operation Demonstrated at Venus Temps for > 1 Year

IC Version 1115x8 (120) bit RAM ~ 1000 JFETs; Shared (Tri-State) Read & Write4.65 x 4.65 mm Chip

IC Version 10 4x4 (16) bit RAM

195 JFETs; Separated Read &

Write3 x 3 mm Chip

RAM Chip Output : Prolonged (year+) operation at T ≥ 460 °C.

Increasing Complexity and Capabilities with Each Generation

ROM Chip prior to dicing > 1000 transistors. Preliminary evaluation completed

World’s First ROM Circuit Capable of 500°C Operation

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Results:• A gold interfacial layer was successful up to molten lithium

temperatures, but proved reactive at 465°C• An alternative material: LiBr, has been found to be the most

promising interface layer so far, with LiBr pellets showing noreactive or mechanical effects after being immersed in moltenlithium for 10h at 465°C

• Additionally, the ionic conductivity for LiBr at 465°C was measuredand calculated to be ~1.7 mS/cm2

• When tested in a [Li1.5In]-[LiBr]-[Li] cell at 465°C, the cell showed avery stable voltage of 0.214 V, matching closely with the predictedvoltage in the literature for a [Li]-[Li1.5In] cell at such hightemperatures

Significance:• LiBr has shown excellent stability and electrochemical potential at Venusian

temperatures (465°C) indicates it can be utilized as interfacial layer betweenmolten Li and LAGP

• This would enable LAGP to be used in a molten lithium anode batterysystem—a first of its kind

• Expected results from such a system would be a patent and a high impactmanuscript

Background:• A rechargeable battery for the surface of Venus that can withstand

the extremely high temperature (465°C) of Venus can be obtainedvia a solid ceramic electrolyte

• At 465°C, the high temperature will enable excellent ionicconductivity for the solid electrolyte and for the use of moltenelectrodes which will ensure good contact between the electrode-electrolyte interfaces

• The proposed rechargeable battery is a molten Li anode and S/Secathode with a LAGP ceramic electrolyte

• Since lithium is quite reactive with most surfaces including theLAGP, an intermediate stable layer is required

Title: High Energy, Long Cycle Life, and Extreme Temperature Lithium-Sulfur Battery for Venus Missions

PI: Jitendra Kumar/University of Dayton Research Institute (UDRI), Dayton, OH

(a) (b)

Image above: (a) LiBr pressed pellet showing no adverse mechanical orobservable reactive effects from immersion into molten lithium at 465°Cfor 10h and (b) LiBr used as an electrolyte between (solid) Li1.5In and(molten) Li, showing a very stable voltage of 0.214 V at 465°C

500°C Capable, Weather-Resistant Electronics Packaging for Extreme Environment Exploration

PI: Alan Mantooth*/University of Arkansas, Co-PI: Debbie Senesky/Stanford University

Significance:• The die shear strengths of the Si and SiC dies using the thick-film gold

die attach on the high-temperature post-fired Al2O3 ceramic substratereduced significantly.

• The ceramic die attach had excellent shear strengths on the alumina andsapphire dies and their shear strengths increased after exposure, duepossibly to the formation of a ceramic crystal bonding after the high-temperature annealing.

• Contributors: Simon Ang, Ardalan Nasiri, Errol Porter, Kaoru Porter, TomCannon, Clinton Hardee (University of Arkansas), Debbie Senesky(Stanford university)

Background:• High-temperature capable electronic packaging

potentially enables extreme environment exploration including the Venus surface.

• An electronic packaging technology consisting of the substrate, die-attach, interconnections, and encapsulation was developed to survive the Venus simulator test environment of 460ºC in CO2 ambient at 96 bar pressure for 244 hours.

Results:• Si, SiC, alumina, and GaN-sapphire dies were

attached to a gold-printed alumina substrate using gold and ceramic paste: Die shear strengths met the MIL-STD-885 2011.9 after the Venus simulator test. The gold bond wire daisy-chain resistance had negligible resistance change (about 0.47% resistance reduction) after simulator test.

• The average bond wire pull strengths before and after exposure were 5.78 g-F and 4 g-F, respectively, meeting the minimum MIL-STD standard.

Ceramic packaging test substrate with Si/8835 gold (1), SiC/8835 gold(2), alumina on 503VFG (3), and GaN-sapphire on 989F (4). (a) before, and (b) after Venus simulator exposure.

*New PI, formerly, S. Ang

Science:• Regolith sample acquisition & transport• Pointing of cameras and antennas• Robotic manipulation• Mobility

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Objectives:• Design, build and test an electric motor and position

sensor compatible with Venus surface environment (CO2 at 462C, 90 bar pressure).

• Document fabrication and screening test procedure.• Characterize high temperature reduction in motor

torque and efficiency by dynamometer testing. Compare with analytical predictions.

• Perform motor life test.• Mature HT motor technology from TRL5 to TRL6.

Development of a TRL6 Electric Motor and Position Sensor for VenusPI: Kris Zacny/Honeybee Robotics, Co-I’s: Jeffrey Hall, Jay Polk/JPL;

Frederick Rehnmark, Cody Hyman/Honeybee Robotics

Accomplishments:• Demonstrated 4 hour operation at 465C and

92 bar• Identified corrosion issues for 30 day

operation; shows the need to coat copper windings

Testing of Drilling Operation in High Temperature Chamber at JPL

HOTTech developed high temperature motor

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• We funded a broad portfolio of 12 complementary technologies needed for a long-lived spacecraft or surface lander on Venus or for exploration of the Gas-Giants.

• Most projects made excellent progress with several reaching proposed exit TRL’s, some high risk high payoff ones are (not surprisingly) ran into technical issues and fell behind. Many projects demonstrated functional operation at realistic environmental conditions of Venus.

• Progress Metrics• 15 Journal Publications / 19 Presentations• 3 Patent Applications• 5 Technology Infusions/Transitions

• A HOTTech Integration Project is now underway – coordination and scheduling of the integrated testing plan is on-going. COVID-19 delays are limiting progress on integration activities and testing schedule.

HOTTech Program Summary

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Potential HOTTech-2 Solicitation

Notional Schedule:• Notify VEXAG – Nov. 2020• Release Solicitation – May 2021• Proposal Due – Aug. 2021• Selections Made – Nov. 2021• Awards Start – Feb. 2022

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Solicitation Release

Proposals Due

Award Starts

VEXAG Notification Selections

FY212020 2021 2022

FY22

Scope:Any spacecraft technology relevant to stationary landers capable of surviving 500°C temperatures indefinitely (no rovers, no instruments), for example:• RF Circuits (>100 Mhz)• Power Electronics (>1 amp)• Passive Electronic Components

(capacitors/inductors, resistors)• Low Power Electronics• Actuators/Motors/Lubrication• Energy Storage/Batteries/Harvesting• Sensors/Cameras

Use of NASA Facilities:The use of Environmental Chambers (GRC, GSFC), Micro-Fabrication Clean Rooms (GRC, LaRC, GSFC, etc) can be proposed at full cost; proposers must coordinate with the relevant POCs.

Budget (Pending NASA Appropriations):• $10M: ~6 Awards @ ~$500k/year for 3 years• $1M for Integrated Testing