Venus Lander Research Articles

Recent Progress in Extreme Environment Durable SiC JFET-R Integrated Circuit Technology

This work updates recent progress made by NASA Glenn Research Center on further advancement of its uniquely durable silicon carbide junction field effect transistor and resistor (SiC JFET-R) integrated circuit (IC) technology since HiTEC 2021. Key fabrication process improvements compared to earlier NASA Glenn IC prototype runs have been ascertained via extensive “back end of line” (BEOL) processing experiments conducted on practice wafers over the past two years. The resulting changes to the BEOL process flow employed in the fabrication of “Generation 12” SiC JFET-R wafers are described. The NASA Glenn SiC JFET-R IC prototype “Generation 12” chipset design realizes significantly higher complexity digital and analog integrated ICs aimed at flexibly implementing a broad variety of mission-enabling extremeenvironment electronics demonstrations. SPICE simulations have verified circuit designs ranging from simple amplification of analog sensor signals up through long-duration Venus lander operations and microprocessor-based of electric motor drive.

A fast and robust surface sample acquisition system for a Venus lander

JPL and Honeybee Robotics have designed, built and successfully tested a fast end-to-end sample acquisition and transfer system for the Venusian surface. This full scale prototype system uses a rotary-percussive drill designed to penetrate to a 5 ​cm depth in saddleback basalt in 15 ​min under full Venus surface conditions of 470 ​°C and 92 ​bar pressure and supercritical CO2 atmosphere. The drill features a hollow bit that collects particulate samples created during the drilling process. Sample transfer from drill to lander is done pneumatically using the motive force provided by the high pressure Venus atmosphere to entrain the particles in a high density flow. A cyclone particle separator removes the particles from the flow inside the lander and deposits them into an airlock, while the gas itself flows into a low pressure dump tank. Two samples are provided from the drill, one near the surface and one at 5 ​cm depth. Cross contamination between the near surface and at depth samples is minimized by collecting, but not analyzing, a third sample in between the two primary samples. The airlock is designed to depressurize and cool the particulate samples and then present them to science instruments for composition analysis. The entire drilling and sample transfer process completes in 30 ​min, thereby allowing it to support almost any kind of future short duration Venus lander mission. Results are presented for the first end-to-end drilling and sample transfer experiment conducted in a new specialized test chamber that replicates Venus surface conditions.

Characterizing landing site safety on Venus using Venera panoramas and Magellan radar properties

This study explores an approach for identifying and characterizing sites on Venus where a future lander mission could attain a high probability of safe landing through a synthesis of Venera surface panoramas, Magellan radar properties, and existing global geological maps of the Venus surface. Surface panoramas from the Venera 9 and Venera 13 landers were used to define rock size distributions and to calculate the probability of a hazardous rock encounter for a reference Venus lander design at these specific landing sites. This surface analysis formed the basis and rationale for the development of a set of global filters seeking to identify “safe” 150-km-diameter landing ellipses with Magellan radiophysical properties including root mean square slope, radar backscatter coefficient, and emissivity values similar to the most benign regional plains unit (rp2) mapped by Ivanov and Head [2011] within the Venera 13 landing site. Using this method, 178 unique ellipses for which >95% of pixels exhibited rms slope and radar backscatter coefficient values similar to the Venera 13 rp2 unit were identified across the Venus surface. Of these ellipses, 36 also contained >95% of pixels with similar emissivity values as the Venera 13 rp2 unit. “Safe” ellipses identified by this method were predominantly composed of regional plains, shield plains, and smooth plains as defined in the Venus global geologic map of Ivanov and Head [2011]. Although the method developed in this study for identifying and characterizing safe landing sites on Venus requires several assumptions regarding the correlation of orbiter radar data to surface properties relevant to lander safety, this approach provides a best effort starting point integrating available data for the systematic, relatively objective, and automatic identification of safe landing sites on Venus.

Experimental characterization of lithium-carbon dioxide combustion in batch reactors for powering Venus landers

The extreme environment and low solar availability on the surface of Venus translate to significant power and thermal management challenges for landed missions. The longest mission to the surface of Venus was Venera 13, which operated for ~2 h. To increase duration and scientific scope, future missions will require power systems with greater specific energy to support active cooling. In-situ resource utilization (ISRU) combustion power systems have been proposed with lithium fuel and the ambient atmosphere (96.5% CO2, 3.5% N2) as the oxidizer. Conceptual designs have assumed batch reactors, which may vary in behavior as fuel is consumed and product concentration increases. As such, practically achievable reaction yield and system-specific energy are unknown. In this study, Li-CO2 batch combustion tests were performed to determine such reaction parameters. Five tests were performed with different operating temperatures, heat delivery mechanisms, and approaches for contacting fuel and oxidizer. Fuel utilization was found to generally increase with bulk reactor temperature. At 500–750 °C, fuel utilization was only 40–60%. This increased to ~98% at 900 °C, corresponding to an effective specific energy of 25.6 ± 0.7 MJkgLi−1 based on reactant and product enthalpies. However, endothermic decomposition of produced Li2CO3 occurs at higher temperatures, limiting specific energy. Based on fuel utilization, the lower temperature cases achieved 32–41 MJkgLi,reacted−1. Attempts to increase lower temperature reaction yield were unsuccessful in this investigation. Further development of approaches to improve yield could enhance the technical potential of lithium combustion power systems.

Towards Making SiC ICs Durable and Accessible for Use in the Most Extreme Environments (Including Venus)

The prospects for beneficial application of integrated circuit (IC) capabilities in ambient environments above 450 °C have been significantly improved by recent long-term demonstrations of SiC chips and packaging by NASA Glenn Research Center. This invited paper reviews and updates development of durable SiC IC technology aspects relevant to engineering infusion into beneficial applications, including the first long-duration low-mass Venus lander missions

Long-duration Venus lander for seismic and atmospheric science

An exciting and novel science mission concept called Seismic and Atmospheric Exploration of Venus (SAEVe) has been developed which uses high-temperature electronics to enable a three-order magnitude increase in expected surface life (120 Earth days) over what has been achieved to date. This enables study of long-term, variable phenomena such as the seismicity of Venus and near surface weather, near surface energy balance, and atmospheric chemical composition. SAEVe also serves as a critical pathfinder for more sophisticated landers in the future. For example, first order seismic measurements by SAEVe will allow future missions to deliver better seismometers and systems to support the yet unknown frequency and magnitude of Venus events. SAEVe is focused on science that can be realized with low data volume instruments and will most benefit from temporal operations. The entire mission architecture and operations maximize science while minimizing energy usage and physical size and mass. The entire SAEVe system including its protective entry system is estimated to be around 45 ​kg and approximately 0.6 ​m diameter. These features allow SAEVe to be relatively cost effective and be easily integrated onto a Venus orbiter mission. The technologies needed to implement SAEVe are currently in development by several funded activities. Component and system level work is ongoing under NASA’s Long Lived Insitu Solar System Explorer (LLISSE) project and the HOTTech program.. LLISSE, is a NASA project to develop a small Venus lander that will operate on the surface of Venus for 60 days and measure variations in meteorology, radiance, and atmospheric chemistry. LLISSE is developing a full-function engineering model of a Venus lander that contains essentially all the core capabilities of SAEVe thus greatly reducing the technology risk to SAEVe.The SAEVe long duration Venus lander promises exciting new science and is an ideal complimentary element to many future Venus orbiter missions being proposed or planned today.

Transition Metal Phosphorous Trisulfides as Cathode Materials in High Temperatures Batteries

The challenging environment of high temperature and high pressure on the Venus surface limit the battery options for Venus landers and surface probes. High temperature batteries employing Li alloy anodes, molten salt electrolytes and FeS cathodes were demonstrated to be resilient and operational for several days. For further improvements in performance, i.e., both specific energy and operational life, new high-capacity cathode materials are needed. Transition metal phosphorus trisulfides (TMPS3) are promising with considerably higher (2X) specific capacity, specific energy and energy density, by virtue of their ability to react with more than two lithium ions. This papers describes the assessment of these cathodes for high temperature batteries to power future Venus landers and probes. Manganese, iron, cobalt and nickel phosphorus trisulfides were synthesized and characterized by Scanning Electron Microscopy (SEM)/Energy Dispersive X-ray Spectroscopy (EDAX) and X-ray Diffraction (XRD) and tested in our high-temperature laboratory cells at 475 °C using cyclic voltammetry (CV) and galvanostatic discharges at different rates. Mn, Fe and Ni phosphorus trisulfides showed reversible behavior in cyclic voltammetric measurements. In the discharge tests, NiPS3 displayed the highest capacity out of the three metal phosphorous trisulfides tested at both C/20 and C/720 rates, with higher voltages and slightly higher capacity than FeS, followed by FePS3, while MnPS3 displayed relatively poor performance at C/20. Cathodes extracted from the discharged cells contain the transition metal (Fe, Ni or Mn) and Li2S by XRD, as expected from the reaction scheme.

Geodesic domes for planetary exploration

Abstract Venus and the Ocean Worlds are emerging areas of interest for space exploration, as they can potentially host, or have hosted, conditions compatible with life. Landers and probes for in-situ exploration, however, must deal with very high external pressure, due to the environmental conditions, often resulting in thick and heavy structures. Robust, reinforced shell structures can provide a lightweight solution for the primary structure. In this frame, the isogrid layout is already a standard in aerospace, especially for flat panels or cylindrical shells. In this paper, isogrid-stiffened hemispherical shells, or “geodesic domes”, are described, focusing on the case of a concept of a Venus lander. Early design methods for both plain and geodesic domes subjected to external pressure are presented, providing design equations. Additive Manufacturing is identified as the key technology for fabricating metallic geodesic domes, due to the complexity of the internal features. Moreover, it allows to fabricate ports and integrated thermostructural systems in the same process, potentially resulting in improved performance or cost and schedule savings.

High temperature primary battery for Venus surface missions

The hostile environment of high temperature and CO2 pressure has limited previous Venus surface mission durations to less than 2 h giving only a glimpse of the Venus surface, despite the use of considerable insulation, phase-change materials, and similar heat sinks to isolate the payload and avionics from high surface temperatures. NASA has initiated studies to develop new power technologies that can tolerate the high Venus surface temperature of 465 °C and pressure of 92 bar, and operate for future long-duration Venus landers and probes. Such in-situ investigations are crucial to gather basic information on the crust, mantle, core, and bulk composition of Venus for understanding the evolutionary paths of Venus in relation to Earth. In this paper, we describe the development of high temperature primary batteries based on lithium alloy anodes, transition metal sulfide cathodes, and molten salt electrolytes. Among the various cathode materials examined for thermal stability and for electrochemical activity, FeS has emerged as the most suitable cathode. With optimized cell components, cell design, and operational parameters, laboratory test cells were fabricated, which demonstrated continuous operation of ~26 days at 475 °C. These batteries will enable new long-duration surface missions for detailed surface exploration of Venus.

Analysis of lithium-combustion power systems for extreme environment spacecraft

The longest duration mission on the Venus surface was Venera 13 at just over 2 h. This time constraint was due to limited battery power life and craft thermal management challenges. A lithium combustion based power system has been proposed to increase landed mission durations for Venus and other extreme environment targets. This paper presents a new detailed thermodynamic and heat transfer model of a conceptual lithium combustion power system. Findings are applied to specify engineering requirements for potential missions. Results indicate that a lithium combustion power system using the in-situ carbon dioxide atmosphere as an oxidizer could power a Venus lander for up five days (24 h, Earth day) with 185 kg of fuel, delivering 14 kWth thermal energy continuously. Even greater durations are possible if lower power missions are considered. The potential performances of a Li-CO2 powered Stirling engine and sulfur-sodium batteries were compared. It was found that sulfur-sodium batteries would require about 1.75–2.5 times more mass to provide 1 kW of power output for mission durations of five to ten days, respectively. A lithium combustion power system with a sulfur-hexafluoride oxidizer could power a Europa lander at 94W with a Stirling engine for up to twenty days with 43 kg of reactants mass. Lithium-combustion activated Stirling engines and TEG arrays were compared with batteries to meet this power and mission duration requirement. It was found that batteries would require less mass than either lithium-fueled system. However, for mission durations longer than twenty-six days the Stirling engine power system may require less total mass than batteries. Future work will include laboratory-based experimental studies to validate results and improve heat transfer closure models.

Venus Lander Electronics Payload Thermal Management Using a Multistage Refrigeration System

This paper presents the analysis and optimization of multistage refrigeration thermal control system for use in cooling electronics payloads on Venus lander missions. The paper outlines the challenges associated with thermal management of electronics in the extreme temperature and pressure environment of Venus. The multistage cascaded vapor compression refrigeration is comprised of a topping cycle using methyl linoleate fatty acid methyl ester with intermediate Supercritical Carbon Dioxide and Transcritical Carbon Dioxide cycles and a bottoming cycle using R-410A refrigerant. Results for analysis optimization of the cascade cycle using MATLAB’s genetic algorithm are presented, which demonstrate the effect of the low-side evaporator pressure on the coefficient of performance of the system. A study of the bottoming working fluid selection shows Ammonia to be a better candidate working fluid for the bottoming cycle than R-410A refrigerant. The paper then presents analysis results for the four-stage cascade refrigeration cycle Ammonia/Supercritical Carbon Dioxide/Transcritical Carbon Dioxide/Methyl Linoleate Fatty Acid Methyl Ester for a refrigeration effect of 100 W with payload at 100°C and a hot-sink temperature of 465°C, lending an optimized total cycle compressor power of approximately 115 W corresponding to a coefficient of performance of 0.87 for the cascade system. The paper presents preliminary design of the heat-rejection system radiator used to interface the cascaded system to the Venus atmosphere.

Tougher than hell.

Venus is closest in size and composition to Earth. It9s also our nearest neighbor. Yet for decades it has remained veiled. NASA hasn9t sent a mission there since 1989, and although Europe and Japan have sent orbiters there more recently, their investigations have stopped largely at the top of the planet9s thick sulfur clouds. No craft has touched down on the surface since 1985, when the Soviet Union sent the last in a series of Venus landers, and for good reason: At temperatures of 460°C and pressures of 90 bars, the spacecraft never survived more than a couple of hours. Now, researchers at NASA9s Glenn Research Center in Cleveland, Ohio, are developing computer chips, based on silicon carbide, that can handle the extreme environment. The chips could enable landers to survive on the surface for weeks instead of hours. By early next decade NASA may be able to land long-lived robots that could measure wind, temperature, chemistry, pressure, and seismic waves—data that could help decipher whether Venus9s interior is still geologically alive.

Prolonged silicon carbide integrated circuit operation in Venus surface atmospheric conditions

The prolonged operation of semiconductor integrated circuits (ICs) needed for long-duration exploration of the surface of Venus has proven insurmountably challenging to date due to the ∼ 460 °C, ∼ 9.4 MPa caustic environment. Past and planned Venus landers have been limited to a few hours of surface operation, even when IC electronics needed for basic lander operation are protected with heavily cumbersome pressure vessels and cooling measures. Here we demonstrate vastly longer (weeks) electrical operation of two silicon carbide (4H-SiC) junction field effect transistor (JFET) ring oscillator ICs tested with chips directly exposed (no cooling and no protective chip packaging) to a high-fidelity physical and chemical reproduction of Venus’ surface atmosphere. This represents more than 100-fold extension of demonstrated Venus environment electronics durability. With further technology maturation, such SiC IC electronics could drastically improve Venus lander designs and mission concepts, fundamentally enabling long-duration enhanced missions to the surface of Venus.

Venus high temperature atmospheric dropsonde and extreme-environment seismometer (HADES)

The atmospheric composition and geologic structure of Venus have been identified by the US National Research Council׳s Decadal Survey for Planetary Science as priority targets for scientific exploration; however, the high temperature and pressure at the surface, along with the highly corrosive chemistry of the Venus atmosphere, present significant obstacles to spacecraft design that have severely limited past and proposed landed missions. Following the methodology of the NASA Innovative Advanced Concepts (NIAC) proposal regime and the Collaborative Modeling and Parametric Assessment of Space Systems (COMPASS) design protocol, this paper presents a conceptual study and initial feasibility analysis for a Discovery-class Venus lander capable of an extended-duration mission at ambient temperature and pressure, incorporating emerging technologies within the field of high temperature electronics in combination with novel configurations of proven, high Technology Readiness Level (TRL) systems. Radioisotope Thermal Power (RTG) systems and silicon carbide (SiC) communications and data handling are examined in detail, and various high-temperature instruments are proposed, including a seismometer and an advanced photodiode imager. The study combines this technological analysis with proposals for a descent instrument package and a relay orbiter to demonstrate the viability of an integrated atmospheric and in-situ geologic exploratory mission that differs from previous proposals by greatly reducing the mass, power requirements, and cost, while achieving important scientific goals.

Planetary seismology—Expectations for lander and wind noise with application to Venus

The amplitudes of seismic signals on a planetary surface are discussed in the context of observable physical quantities – displacement, velocity and acceleration – in order to assess the number of events that a sensor with a given detection threshold may capture in a given period. Spacecraft engineers are generally unfamiliar with expected quantities or the language used to describe them, and seismologists are rarely presented with the challenges of accommodation of instrumentation on spacecraft. This paper attempts to bridge this gap, so that the feasibility of attaining seismology objectives on future missions – and in particular, a long-lived Venus lander – can be rationally assessed.For seismometers on planetary landers, the background noise due to wind or lander systems is likely to be a stronger limitation on the effective detection threshold than is the instrument sensitivity itself, and terrestrial data on vehicle noise is assessed in this context. We apply these considerations to investigate scenarios for a long-lived Venus lander mission, which may require a mechanical cooler powered by a Stirling generator. We also consider wind noise: the case for decoupling of a seismometer from a lander is strong on bodies with atmospheres, as is the case for shielding the instrument from wind loads. However, since the atmosphere acts on the elastic ground as well as directly on instruments, the case for deep burial is not strong, but it is important that windspeed and pressure be documented by adequate meteorology measurements.

Atmospheric tides on Venus: III. The planetary boundary layer

Diurnal solar heating of Venus' surface produces variable temperatures, winds, and pressure gradients within a shallow layer at the botton of the atmosphere. The corresponding asymmetric mass distribution experiences a tidal torque tending to maintain Venus' slow retrograde rotation. It is shown that including viscosity in the boundary layer does not materially affect the balance of torques. On the other hand, friction between the air and ground can reduce the predicted wind speeds from ∽5 to ∽1 m/sec in the lower atmosphere, more consistent with the observations from Venus landers and descent probes. Implications for aeolian activity on Venus' surface and for future missions are discussed.