New Power Technology for Aerial Missions Ratnakumar Bugga, John-Paul Jones, Michael Pauken, Keith Billings, Channing Ahn,* Brent Fultz,* Kerry Nock,** and James Cutts Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Dr., Pasadena, Ca 91109 *California Institute of Technology, 1200 E California Blvd, Pasadena, CA 91125, **Global Aerospace Corporation, 12981 Ramona Blvd, Irwindale, CA 91706 Atlanta, GA October 13-17, 2019 Extreme Environments on Venus

• Of all the solar system's planets, Venus is the closest to a twin of . • The two bodies are nearly of equal size, and Venus' composition is largely the same as Earth’s. • The is also the closest to Earth's of any solar system planet. • Both worlds have relatively young surfaces, and both have thick atmospheres with clouds (however, it's worth nothing that Venus' clouds are mostly made of poisonous sulfuric acid). • But not enough interest, because of its hostile environment • High Temperature : 25oC at 55 km rapidly increasing to 465oC at the surface

• High pressure: CO2 pressure (90 atm) at the surface

• Corrosive environment: Concentrated H2SO4 droplets in or above the clouds and sulfur compounds • No possibility of extant life, Fig. 1 Venus temperature/pressure vs. altitude. Challenging environment Fig.for in 1 -Venussitu missions temperature/pressure vs. altitude

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 2 Prior Venus Missions Japan Orbiter

• Orbiters: Russian (4-13) series [4], the US and the European and Japan Akatsuki (2010) In-situ Missions • Balloons: Several missions have been implemented successfully, e. g., the Russian "VEGA" missions (1985). VEGA balloon (21 kg) • Two balloons of 3.5m diameter super-pressure balloons with 7-kg instrumented payload were deployed into the atmosphere, and floated for 48 hours at about 54 km altitude. • Powered by primary batteries (1 kg of lithium batteries with 250 Wh), the VEGA balloons operated only in the benign temperature regime. • Surface missions (/Surface Probes): Probes from the Venera VEGA lander (750 kg) series, Vega program and Venera-Halley probes. • Successfully landed on Venus and transmitted images of the Venus surface but lasted only <2 h due to the failure of batteries and electronics, even with extensive thermal insulation, phase-change materials and similar heat sinks.

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 3 Venus Continues to be an Enigma • Despite these missions, major questions remain: • What is the precise chemical composition of the atmosphere and how does it vary with location and altitude? • When and how did the runaway greenhouse effect occur on Venus? • How did the form and evolve? • What are the morphology, chemical makeup and variability of the Venusian clouds and their impact on the climate? • What are the processes controlling the atmospheric super-rotation? • What are the processes governing Venus seismicity and its interior structure? • How have the interior, surface, and atmosphere interacted as a coupled system over time? • The orbital and high-altitude (55-65km) balloon missions are stymied by the opaque clouds. • To address these questions and others, it is essential to have missions that allow long-term, in situ measurements at lower altitudes in the Venusian atmosphere.

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 4 Comparative Analysis of Platforms Recent VEXAG (Venus DesignExploration Sweet and Analysis Spot Group) Study Assessment of Different Aerial Platforms Variable Altitude Enhanced Range* Variable Altitude Nominal Range*

Hybrid airship (3D control)

Color Code Technology Maturity Fixed Altitude Very High Solar Airplane High Science Value Science (3D control) Moderate Low to Moderate Low

Size/Complexity * Nominal Range Altitude controlled balloons represent a “sweet spot” in Altitude 50 to 60 km

the aerial platform option space. * Enhanced Range Altitude 40 to 60 km Venus Aerial Platforms Study Pre-Decisional Information -- For Planning and Discussion Purposes Only 9 • The variable-altitude balloons were determined to represent a scientific and technical “sweet spot”. • Have the potential for a substantial enhancement of the science without a commensurate increase in risk. • Aerial platforms enable investigations of not only the atmosphere of Venus but also its interior and surface. 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 5 Venus Environments and Balloon-related Technologies

75 km - 60 °C, 0.01 atm

70 - 45 °C, 0.04 atm Allowable range of UV Typical poly- absorber allowable 1100 w/m2 range with ethylene 60 Cloud standard balloon 0 °C, 0.3 atm layers electronics material 30 °C, 0.5 atm VEGA flight 60 C, 0.8 atm ° Abundant altitude 50 solar Allowable 48 93 °C, 1.4 atm power range of Allowable Kapton FN range with balloon 140 °C, 3.2 atm commercial material 40 high temp Range electronics targeted by VIP-INSPR 200 °C, 7.2 atm 30 Altitude, km Altitude, 200 w/m2

20 Useful 350 °C, 33 atm range of Lowest metal 10 scale balloon height, material aerial imaging viable 0 460 °C, 92 atm 16 Compiled by Jeff Hall (JPL) 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 6 Power Generation Technologies for Venus Missions

Radioisotope Thermoelectric Generators (RTG)

Triple junction solar cell efficiency vs. altitude

Solar Arrays

• Implementing conventional long-duration power technologies, such as solar array or radioisotope power systems is challenging. • Reduced solar flux below the clouds and at the surface: 2600 W/m2 (or roughly twice that of Earth’s solar flux) at high altitudes and ~9 W/m2 at the surface. • The current Multi-mission Radioisotope Thermoelectric Generator is not capable of operating at 90 bar pressure and a +465°C heat sink. • Dynamic RPS is promising but significant development is needed and also requires an energy storage device for load levelling. 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 7 Battery Options Non-Existent or Limited

• There is no battery system that is thermally stable over 60-20 km (0-350oC) • Li-ion batteries: Not stable above 70oC.

• Li primary batteries (Li-CFX, Li-SOCl2): Not stable above 150oC • High temperature sodium rechargeable batteries do not function below 250oC • Even with thermal management, the survivability life is limited to a few hours. • Thermal management system (phase change materials) would need considerable mass and volume at the expense of payload

• A new power generation and energy storage approach is required to enable an extended exploration of the Venus atmosphere and near-surface environments.

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 8 VIP-INSPR (NIAC) Novel power source using in-situ resources for Long-duration VABs

• A solar array will power the probe at high altitude and generate H2 and O2 with Solid Oxide Electrolysis Cell (SOEC), using water carried from ground. • H2 willVenusbe stored Probein a withmetal Inhydride-situ Powerand O2 in Generationa tank. (VIP-INSPR) • Venus •InteriorSolid ProbeOxide based Fuelon in-sCellitu resources(SOFC) (VIPwill-INSPR)provide for powerpower generationat low (VIPaltitudes-INSPR). with the • Generationstored of hydrogenH2 and (fuel)O and2. oxygen at high altitude from in situ resources, i.e., solar energy and water (from the• VenusH and cloudsO or willcarriedbe fromregenerated ground) and generationat high ofaltitudes power at lowfrom altitudeswater utilizingproduced fuel in a high(a temperatureVenus 2fuel cell. 2Interior Probe Using In-situ Power and Propulsion • Hydrogen closedused as– asystem) . for buoyancy to navigate the probe across the Venus clouds. • Can operate for extended durations (not limited by power(VIP or lifetime).-INSPR) • A H2 balloon will be used for buoyancy and altitude control (60-15 km).

ApproachHigh Altitude Balloon • Kapton •balloonAbundant solar power Solar power Electrolyze H O • Bring stored H O (Harvesting may be challenging) 2 • H lifting gas & for 2 2 60 km energy storage

descend • Solar power Electrolyzeat high H2O to generate H2 and O2 altitude ascend • H stored in metal 2 Descend below clouds hydrides • Store ~200 g H from balloon in metal hydride 2 H /O Fuel cell • Regen. solid oxide• Operate fuel on solid oxide fuel cell (SOFC) 2 2 cell (SOFC) power• Store H2O byproduct 10-20 km below clouds, at night,Ascend above clouds

and regenerates H2/O• Release2 H2 back into balloon • Operate on solar power 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 9 • Electrolyze H2O back into H2 and O2

jpl.nasa.gov Schematic of Power Architecture of our Venus VAB

High T PV

Simple architecture.

10/13/2019 KB # 10 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 7 High-Temperature Tolerant Solar Cells

• JPL (Grandidier et al.) is developing high temperature tolerant solar cells under NASA’s HOTTECH Program, using wide bandgap materials, since the higher voltage of wide bandgap solar cells results in less degradation. • Si solar cells (1.1 eV) lose ~ 0.45% /oC increase in operating temperature. GaAs cells (1.4 eV) lose about 0.21% per oC. • For our Venus VAB, however, it is the lifetime that is crucial, since power at low altitudes is provided by fuel cell.

2 For 300W at 60km altitude we need: 0.536 m solar cells Power available for that size at other altitudes:

Altitude Solar cell Power (km) (W) 0 4.7 5 11.8 10 20.1 15 24.5 20 31.4 25 38.6 30 45.7 35 53.1 40 60.2 45 97.3 50 137.3 55 217.0 60 300.0

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 11 Hydrogen Storage Using Metal Hydrides • Metal hydrides are attractive materials for hydrogen storage. • No need for compressors and volumes are considerably lower than real gas law requirements • Several materials exist with different amount of hydrogen absorption capacities and plateau pressures.

Pressure-Composition-Temperature (PCT) curves Hydride kinetics

Kinetic curves of the desorption of the activated ternary Mg2Ni1-xZrx alloys for three values of x (0, 0.1 and 0.3) at 340 °C and under a pressure of 1 atm.

• Absorption/desorption pressures are characteristic • Absorption/desorption kinetics are rapid both at 25- 300°C. of materials 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 12 Van’t hoff plot

• Absorb H2 at low temp/high altitude

• Release H2 at high temp/low altitude (endothermic) • Modulate altitude by adding or

removing H2 from balloon • Store energy for fuel cell

• Metal hydrides can be selected based on the temperature (altitude) range

• For 2 kWh of energy, ~100 grams or 42.4 moles of H2 and 21.2 moles of O2 would be required. Another 200 g of H2 is required for altitude control (total of 15 kg of MH) • The initial fuel requirements will be part of the launch package

• The system will be encased in a Titanium shell for stability against high pressure, temperature and H2SO4

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 13 H2/O2 Solid Oxide Fuel Cell / Electrolyzer • A reversible solid oxide fuel cell (RSOFC) is a device with a solid oxide electrolyte that operates efficiently at ~800oC as fuel cell and electrolysis cell, generating power from H2 and O2 (and produce H2O) in fuel cell mode and generating H2 and O2 (from H2O) during electrolysis. • Standard Ni/YSZ/LSM SOFCs operate from 750-1000 °C • High reliability (>19,000 hr demonstrated) • High power density (0.75 W/cm2) • Planned demonstration on 2020 (MOXIE) Regenerative (Reversible) SOFC Data Provided by JSC

Mars Oxygen In-Situ ResourceMOXIE Utilization Experiment (MOXIE)

• High Power density : 0.3 W/cm2

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 14 Notional Balloon Altitude Control

• Altitude cycling and control is achieved by means of buoyant gas storage.

• Taking as little as 200 g of H2 gas from the envelope and storing it at much higher density than ambient (at lower altitudes), results in negative balloon buoyancy that causes the balloon to descend to 10 km in just over 7 hours. • Withdrawing smaller amounts from the balloon results in longer descent times. • Re-filling the balloon with stored gas allows the balloon to return to positive buoyancy and ascend. • Carried out by our collaborators at the Global Aerospace Corporation in Pasadena, CA

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 15 Entry, Descent and Inflation Sequence

Entry System Components

• Deployed by a carrier stage. • EDI , PV deployment and initial checks powered by high energy (500 Wh/kg) Li primary battery (Li-CFX) KB # 16 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only Balloon at High Altitude

High Altitude Check Fuel Generation H2 Capture From Balloon Actions: • Jettison high pressure H tank Actions: Actions: 2 • Capture H in metal hydride to High• DeployAltitude PV and System Heat SOFC CheckFuel Generation• ElectrolyzeFuel H 2GenerationAboveO into H2 and Clouds O2 Above Clouds 2 • Capture H in metal hydride begin to descend • Jettison primary battery 2 60 km High Altitude System60 Check km 60 km Primary Instruments 60 km Instruments Battery Primary Battery H (Jettisoned) Actions: H 2 Actions: (Jettisoned) 2 Storage Solar Panels Storage 7.96 kg H2 Solar Panels

7.96 kg H2 100 g 100 g • Electrolyze H O 200 W

H 2 H • HElectrolyze H2 O 200 W

Actions: 2 2 H

Actions: Balloon 2 Storage Balloon Solar Panels 2 8.06 kg H2 Solar Panels 300 W Storage 0 g H • Jettison high pressure8.06 kg H2 into H2 and O2 Buoyancyinto H2 and O2 Buoyancy 300 W 0 g H Power Power • Jettison high pressure Balloon & Altitude & Altitude H tank • Capture H2 2 in • Capture H2 in bus bus 2 Balloon Buoyancy PowerControl Control H2 tank Buoyancy & Altitude metal2 hydride bus metal hydride • Deploy PV Control Power & Altitude 100 W • Deploy PV • Heat SOFC bus 100 W Control Oxygen Oxygen Storage • Jettison primary battery H2 H Storage • Heat SOFC Oxygen 2 0 kg O 0 kg O H2 Storage 2 • Jettison primary battery Duration of 0 kg O

H O 2 DurationWater Collectionof 2 H O 24 hrs Oxygen Water Collection 2

2 Heat Duration of H O Storage 24 hrs H2 2 Exchanger Heat O2

Water Collection 1.35 kg SOEC O2 1 hrs H Exchanger 1.35 kg 2 Heat 0 kg O SOEC H O O Exchanger Altitude: ~64 km 2 2 O 1.35 kg SOFC/SOEC Pressurized Altitude: ~64 kmH Altitude: ~64 km Altitude: ~64 km Altitude: ~64 km 2 Pressurized O Power Source: PV Water Storage Duration of Altitude: ~64 km 2 PowerDuration Source: of PV Water Storage Power Source: primaryPressurizedHSOFC2O battery operational: No Power Source: PV Red arrows indicate Power Source: PV Power Source: Water Collection Water Storage T+0.5Red hrs arrows indicate 1 hrs SOFC operational: no SOFC24 hrsoperational: No direction of H flow primary batteryHeat SOEC operational: Yes Red arrowsWater indicate SOFC operational: No 2 SOFC operational: No Exchanger O2 SOECPump operational:Vaporizer Yes Water direction of H2 flow

1.35 kg Yellow arrow indicate SOEC operational: no SOFC/SOECWater direction of H flowSOEC operational:Vaporizer Yes SOEC operational: No SOFC operational:H no 2 Pump

2 Vaporizer Yellow arrow indicate Altitude: ~64 kmSOEC operational:O no Pump Yellow arrow indicate direction of power flow Pressurized direction of power flow 0 5 10 15 direction20 of power25 flow30 Power Source: Water Storage KB # 33 Timeline 0(hr) 5 10 15 20 25 30 0 5 10 15 20 25 30 Red arrows indicate Timeline (hr) KB # 33 primary battery Timeline (hr) KB # 31 SOFC operational: no Water direction of H2 flow SOEC operational: no Pump Vaporizer Yellow arrow indicate 10/13/2019 direction of power flow KB # 17

0 5 10 15 20 25 30 Timeline (hr) KB # 31 Balloon Descent to Lower Altitudes and Return

Decent Below Clouds to 50 km Decent Below Clouds to 24 km Ascend above clouds Actions: Actions: Actions: • Descend to 24 km • Descend to 50 km Ascend• Add 120 above g of H2 to clouds the balloon Decent• Operate Below SOFC Clouds to 24 km • Operate SOFCDecent Below Clouds •toAscend 24 km above clouds 60 km 60 km 60 km

Instruments Instruments Instruments

Actions: H2 H2 H2 Storage Solar Panels 8.06 kg H2 330 W Solar Panels Solar Panels - Storage • Add 120 g ofStorage 80 g

Actions: 7.76 kg H2 Actions: 7.76 kg H2 H 61 394 g 394 g Balloon 2 76 W 76 W H H 30-300 W

2 H2 to the Buoyancy • Descend to 24 km Balloon • Descend to 24 km Balloon 2 Power Buoyancy 46 W & Altitude 46 W Power Buoyancy balloon bus • Operate SOFC & Altitude • Operate SOFC ControlPower bus & Altitude bus Control Control• Ascend above

clouds 30 W Oxygen

30 W H Storage Oxygen 30 W 2 Oxygen 0.66 kg H2 Storage O H2 Storage 2 0.76 kg H O O 0.76 kg Water Collection 2 2 O

Heat2 H2O Exchanger O2 Water Collection 0.60 kg SOFC H2O H 2 Heat Altitude:Water 24 Collectionà 64 km O Exchanger O2 Heat Pressurized 0.49 kg SOFC H PowerExchanger Source: PV + SOFC WaterO2 Storage 2 0.49 kg O SOFC Altitude: 30 à 24 km H Red arrows indicate Altitude: 64 à 50 km SOFC2 operational: Yes Pressurized Altitude: 30 à 24Altitude:km 30 àO 24 km Altitude: 24 à 64 km Power Source: PV + SOFC Water Storage SOECPressurized operational: No Water direction of H2 flow Power Source: PV + SOFC Power Source: PV + SOFC Vaporizer SOFC operational: Yes Red arrows indicatePower Source: PV + SOFC Water Storage T+10.5Pump hrs Power Source: PV + SOFCYellow arrow indicate SOFC operational: Yes Red arrows indicate SOEC operational: T+1.3No hrs Water direction of HSOFC2 flow operational:SOFC Yes operational: Yes SOFC operational: Yes direction of power flow Vaporizer Pump Water direction of H flow SOEC operational: no Yellow arrowSOEC indicate operational: SOEC No operational:0 No5 10 15 20 25 2 30 Vaporizer SOEC operational: No direction of power flow Pump Timeline (hr) Yellow arrow indicate KB # 23

0 5 10 15 20 25 30 direction of power flow Timeline (hr) KB # 22 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Timeline (hr) Timeline (hr) KB # 22

10/13/2019 KB # 18 Venus Probe – Notional Operational Sequence

Altitude stabilization at 64 km Ascent to 60 km Release H2 into balloon to ascend Loiter at 24 km Altitude stabilization Descent to 24 km Descent to 30 km Descent to 40 km Descent to 50 km H2 capture from balloon Fuel generation System check Altitude stabilization Fill Balloon 0 5 10 15 20 25 30 Time, h

• 24 h required to generate adequate hydrogen for the fuel cell to support low altitude dive • About 9 h to complete one altitude excursion (60-24 km) during daytime • Another 24 h for regeneration of fuel for the fuel cell to support nighttime operations

KB # 19 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only Notional Balloon Descent and Ascent Scheme

Start End Duration Balloon SOFC SOEC Activity Actions MH H2 (kg) H2O tank (kg) O2 tank (kg) PV (w) (hr) (hr) (hr) H2 (kg) (w) (w) Fill Balloon 0.0 0.1 0.1 Fill balloon from high pressure tanks 0 0 1.35 0 0 0 0 Jettison high pressure H2 tank System check 0.1 1.1 1.0 Deploy PV, Heat SOFC 8.06 0 1.35 0 0 0 0 Jettison primary battery Electrolyze H2O into H2 and O2 Capture H2 in metal hydride Altitude stabilization 1.1 1.2 0.1 7.96 0.1 1.35 0 300 0 100 Transfer excess H2 from balloon to hydride Electrolyze H2O into H2 and O2 Fuel generation 1.2 25.2 24.0 7.96 0.1-0.2 1.35-0.45 0-0.8 300 0 100 Capture H2 in metal hydride Capture H2 in metal hydride to H2 capture from balloon 0.0 0.5 0.5 begin to descend 7.76 0.4 0.45 0.8 300 0 100 Descend to 50 km Descent to 50 km 0.5 1.8 1.3 Operate SOFC 7.76 0.4-0.398 0.45-0.47 0.8-0.79 300-137 30 0 Descend to 40 km Descent to 40 km 1.8 3.0 1.3 Operate SOFC 7.76 0.398-0.396 0.47-0.48 0.79-0.78 137-60 30 0 Descend to 30 km Descent to 30 km 3.0 4.3 1.3 Operate SOFC 7.76 0.396-0.394 0.48-0.49 0.78-0.77 60-46 30 0 Descend to 30 km Descent to 24 km 4.3 5.5 1.3 Operate SOFC 7.76 0.394-0.392 0.49-0.50 0.77-0.76 46-31 30 0 Operate SOFC Altitude stabilization 5.5 6.0 0.5 Stabilize balloon at 24 km 7.94 0.214 0.5 0.76 31 30 0 Loiter at 24 km 6.0 7.5 1.5 Operate SOFC 7.94 0.213-0.2 0.5-0.6 0.76-0.66 31 200 0 Add H2 in Balloon to rise back Release H2 back into balloon7.5 8.0 0.5 above clouds 8.06 0.08 0.6 0.66 31 30 0 Ascent to 60 km 8.0 18.0 10.0 Ascend above clouds 8.06 0.08-0.067 0.6-0.72 0.66-0.56 31-300 30 0 Capture H2 from balloon Altitude stabilization 18.0 18.5 0.5 Regenerate Fuel 7.96 0.167 0.72 0.56 300 0 100 Fuel generation 0 24 24.0 Regenerate Fuel 7.96 0.167-0.197 0.72-0 0.56-1.2 300 0 100

• 6 h for the descent, ~8 h of science at 24 km and 10 h to return to the original high altitude, with 200 g of H2 transfer • Power share between PV and Solid Oxide Fuel cell 10/13/2019 Preliminary (VIP-INSPR) Balloon Design • A balloon system design that can cycle in the following altitude range of 20 to 60 km (goal) • Assumed suspended mass is 100 kg; Pay load ~20 kg of science payload • Single, near-spherical zero pressure balloon: simple and lightweight • Post-entry deployment with use of internal lines to reduce loads on envelope. • 1 mil thick Polyimide (e.g. Kapton) or Polybenzimidazole (PBI) Film. • 0.5 mil Teflon coating, vapor deposited gold or SiO for 2 Soviet Vega Balloon mock up protection. • For 100 kg suspended mass, the envelope mass is 20.8 kg and diameters are 9.4 m (at 60 km) and 2.1 m (at 20 km). • Envelope needs to support load of suspended mass in highest temperature regime. • Venting and fill features.

• Carried out by our collaborators at the Global Aerospace Corporation in Pasadena, CA • 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 21 Preliminary (VIP-INSPR) Balloon Design

Initial Design Comparison VIP-INSPR Vega Aerostats Type ZPB Spherical SPB Gas 8.1 kg of Hydrogen 2.1 kg of Helium Volume 855 m3 20.6 m3 11.8 m (65 km) Diameter 3.4 m 1.1 m (10 km) Envelope Material 1 mil coated Kapton Teflon Laminate Envelope Density 37.8 g/m2 300 g/m2 12.5 kg Envelope Mass 16.6 kg (Includes 13 m tether Payload Mass (Science) 20 kg 6.9 kg Design Altitude 10-65 km 54 km

• Carried out by our collaborators at the Global Aerospace Corporation in Pasadena, CA

• 10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 22 Possible Instruments on Variable Altitude Balloons • ATMOSPHERIC GAS COMPOSITION • Mass Spectrometer - Measure atmospheric species including noble gases and their isotopes. • Tunable Diode Laser Spectrometer- Measures traces species including isotopic abundances. • UV/IR spectrometer- Measures atmospheric species from their spectral signatures. • Chemical Sensors (MEMS based) -Measures chemical species particularly at high temperature. • CLOUD AND HAZE PARTICLES • Nephelometer- Measures size, scattering properties and abundance of cloud and haze particles • Optical Atmospheric Counter- Measures size, scattering properties and abundance of cloud and haze particles • Raman Lidar - Measures Raman scattering behavior of aerosols • Lidar- Measures optical depth from scattered light - bulk properties of cloud particles • Imaging microscope - Images larger cloud particles captured on a filter. • Aerosol Mass Spectrometer - Measures the chemical composition of individual aerosol particles • ATMOSPHERIC STRUCTURE • Atmospheric structure instrument - Measures temperature, pressure and possibly vertical wind speed. • Net Flux Radiometer - Measures upward and downward flux of radiation in multiple spectral bands • Ultra Stable Oscillator - Facilitates measurement of wind from Doppler signatures • GEOPHYSICAL SENSORS • - Measures remnant magnetic fields • Electromagnetic Sounder -Measure crustal thickness and conductivity • Infrasound sensors - Measures infrasound from Venus quakes and volcanoes • Lightning Detector- Measures transient EM signals indicative of lightning. • SURFACE OBSERVATIONS • NIR imager - Images thermal emission from the surface at higher resolution than from space. • Visible imager - Images surface in visible light. Only feasible from below 10 km • Radar altimeter - Measures range to the surface.

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 23 Summary and Conclusions

• The new power technology concept developed here, involving a combination of high temperature PV, Metal Hydrides and Regenerative Solid Oxide Fuel Cells will enable sustained in situ exploration of Venus over a wide range of altitudes. • Although the VAB technology for the simplest type of missions is ready now, a multi-year investment program focusing on variable altitude capability would enhance the science capability of these platforms • Among the opportunities for the application of VAB technology are: – Joint NASA Russian Venera D Mission Concept– NASA contribution • Venus Flagship Mission – currently being studied by NASA • Venus Bridge – atmospheric elements • Future competitive opportunities – New Frontiers and Discovery

10/13/2019 Pre-Decisional Information – for Planning and Discussion Purposes Only KB # 24 The work described herein was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with National Aeronautics and Space Administration (NASA), and supported by NASA Advanced and Innovative Concepts (NIAC) Program.

10/13/2019