Chemical Analysis of Materials Exposed to Venus Temperature and Surface Atmosphere

Abstract

Planetary exploration in the harsh Venus surface environment faces a myriad of technical challenges related to material survivability, durability, and overall reliable systems operation. An understanding of material reactions in Venus relevant atmospheric conditions is core to enabling future successful Venus science missions. This work investigated various candidate materials used in fabricating electronics, sensors, and packaging after exposure to simulated Venus surface atmosphere. The NASA Glenn Extreme Environments Rig is capable of reproducing Venusian temperature, pressure, and atmospheric composition of the Venus surface consisting mostly of CO 2 and N 2 as well as traces of SO 2 , H 2 O, CO, OCS, HCl, HF, and H 2 S. The exposed materials were characterized using Auger electron spectroscopy, X-ray photoelectron spectroscopy, energy dispersive spectroscopy, field emission-scanning electron microscopy, X-ray diffraction, and optical imaging. The reactivity of the sulfur gas constituents with several of the exposed materials were found to have adverse effects on the materials, particularly those composed of transition metals. Alloys, brazes, and cladded materials all exhibited extensive reactions. In contrast, compounds of SiC, SiO 2 , Al 2 O 3 , and elemental Au and Ir were found to be chemically inert. The fundamental experimental understanding of material interactions with the simulated Venusian environment gained in this study enables improved selection of materials and hardware designs that would increase the success margin of future long duration science mission on Venus.Plain Language Summary Exploration of our sister planet Venus has been severely impeded to date due to its high temperature (467°C), high pressure (90× that of Earth), and hostile surface environment. The atmosphere not only is mostly carbon dioxide and nitrogen but also contains trace amounts of highly reactive compounds of sulfur, chlorine, and fluorine. Previous space probes to the planet lasted at most a couple of hours before the surface environment caused them to fail. A study was done in which various materials used to build spacecraft were put in a chamber specifically designed to simulate the Venus environment, complete with the trace amounts of the corrosive gases. This paper details what happened to the materials that were exposed and explores which ones reacted catastrophically and which ones remained intact and are therefore viable candidates for Venus surface mission use. Based on our findings, we strongly recommend that all future missions test their components in a similar full Venus environment.

Operational Testing of 4H-SiC JFET ICs for 60 Days Directly Exposed to Venus Surface Atmospheric Conditions

“…Ideally, these feedthroughs would relay all electrical signals with excellent fidelity throughout the entire test. In reality however, feedthrough probes (particularly the portions directly exposed to the Venus environmental conditions) employed for the 21-day test were observed to contribute (to increasing degree as the test progressed) significant electrical parasitic effects (including short-circuit failure) [33], [38]. In an attempt to reduce the feedthrough probe assembly electrical degradation and parasitics, a modified feedthrough probe assembly design was implemented for this 60-day test.…”

“…The bond pads on the FT5 chip from Wafer 10.1 were also studied after the 60-day test for comparison with 21-day test bond pad findings from Wafer 9.2 [38]. A field emission scanning electron microscope (FESEM) image of the 60-day post-test bond pad with a gold wire attached is shown in Fig.…”

“…7(b). In-depth analysis of the bond pad materials and the reactions occurring after the 21-day Venus exposure was detailed in [38]. Those results indicated that wherever Pt was exposed to the Venus atmosphere in the absence of overlying Au (as in the case of the bond pad rims in the 21-day test chip from Wafer 9.2), the Pt would react with the sulfur containing gas species and form PtS fibers.…”

Photovoltaic operation in the lower atmosphere and at the surface of Venus

“…We assessed here the effect of high temperature on the solar cell. An understanding of material reactions in Venus relevant atmospheric conditions is needed to enable future Venus missions . In order to survive the Venus corrosive environment, we expect the solar cells will need a suitable encapsulation.…”

Aerial Seismology Using Balloon-Based Barometers

“…On Venus, however, the possibility of a long-duration ground station is remote, as the adverse surface conditions cause rapid failure of electronic systems and instruments. Even relatively simple but hardened oscillator circuits have lasted only up to 161 h when subject to Venus surface conditions in the laboratory [9] and materials used to manufacture electronics have been tested for up to 42 days, exhibiting varying degrees of degradation [10].…”