Leah M. Nakley

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 enabli...

Sixty Earth-Days Test of a Prototype Pt/HTCC Alumina Package in Simulated Venus Environment

This paper presents experimental results of a prototype high temperature co-fired ceramic (HTCC) package with Au/Pt metallization in a three-phase harsh environment test that culminated with 60-day demonstration in simulated Venus surface environment of 465 °C with corrosive atmosphere at 90 bar pressure. The prototype package is based on previously developed and reported HTCC package successfully tested with multiple analog and digital silicon carbide (SiC) high temperatures semiconductor integrated circuits (ICs) at NASA Glenn Research Center in 500 °C Earth air ambient for over ten thousands hours, and short-term tested at temperatures above 800 °C. The three-phase harsh environment test started with 48 hours in 465 °C Earth air, followed by 48 hours in 465 °C nitrogen at 90 bar pressure and 1400 hours in simulated Venus surface environment of 465 °C with corrosive atmosphere at 90 bar. Initial analytical results of the package materials and surfaces after exposure to Venus environment are discussed to assess the stability of the packaging materials in the tested environments. The test in simulated Venus environment was implemented in the NASA Glenn Extreme Environment Rig (GEER). The results of this study suggest that an effective encapsulation of areas of surface metallization and vicinities may help to improve electrical performance of a HTCC alumina packaging system in Venus environment.

Microanalysis of Geologic Materials Exposed to Surface Conditions on the Planet Venus

Crust/atmosphere interactions are thought to play an important role in the Venus greenhouse climate [1]. Limited in situ analyses of the surface of Venus and minimal determination of major and minor constituents in the lower atmosphere provide inadequate insight into possible dominant solid/gas reactions that can occur. Prior experimental modeling provides conflicting hypotheses as to the importance and chemical stability of geologic mineral phases on the surface of Venus [2,3,4]. For this study, we exposed a matrix of geologic material including minerals, rocks, and glasses for 42 days to Venus surface conditions using the Glenn Extreme Environment Rig (GEER) at NASA Glenn Research Center.