Sensor System Development for Long-Lived Venus Surface Lander Applications

Exploration of the surface of Venus involves a number of significant technical challenges. The Venus surface temperature is ~465°C with a 92 atmosphere caustic environment. Previous missions to the Venus surface have operated for no more than ~2 hours due to these conditions. The science community has effectively no in- situ temporal data even for basic measurements such as temperature, pressure, or wind near the Venus surface. However, advances in technology, such as high-temperature sensors and silicon carbide (SiC)-based electronics have matured to a state where simple but long-lived Venus surface exploration is possible. The most advanced example of such an approach is the Long-Lived In-Situ Solar System Explorer (LLISSE) lander system that targets operation on the Venus surface for up to 60 days. A range of subsystem and component technologies to enable system operation on the Venus surface associated with the LLISSE high temperature lander system are envisioned. Development of these technologies either occurred directly as part of previous LLISSE maturation, or in complimentary work in the Hot Operating Temperature Technology (HOTTech) project that also develops technology for long duration surface operations. This overall development includes power, communications, signal conditioning and data processing, imaging, as well as a range of sensor technologies to measure the local surface conditions. The combined technology suite provides the foundation for the future exploration of the surface of Venus far beyond that accomplished historically including long-lived monitoring of Venus surface conditions with a multiparameter sensor suite.

In particular, a range sensor technologies can provide data critical to more completely understand of Venus’ weather, the processes by which chemical species interact in the environment, and better understanding of the surface environment. These sensors include, but are not limited to, temperature, wind, pressure, radiance, and chemical species. Each has a very different measurement approach, targeted science goals, and level of technical maturity. The purpose of this presentation is to provide an overview of the significant amount of development that has taken place related to sensors and sensor systems for extended duration use on the Venus surface. For each sensor, a description of its sensing mechanism, targeted measurement parameters, and stage of development is provided. A high-level description of the state of development of the high temperature electronics supporting such instrumentation is also provided. This presentation does not include a description of a high temperature seismometer, which is presented elsewhere at this meeting.

An example of such sensor development is the protototype Venus wind sensor. This wind sensor is a miniature drag-force anemometer that includes a cantilever with full bridge strain gages at the base. The approach is that wind at the Venus surface bends the cantilever in proportion to the wind’s speed and force, and the strain gages at the base of the cantilever measure that deflection and thus the strength of the wind. These miniatured drag-force anemometers were integrated with a high temperature SiC amplifier and tested in a simulated Venus surface environment. Specifically, prototype drag-force anemometers were tested for up to 34 days in the Glenn Extreme Environment Rig (GEER) that simulates Venus surface conditions . These prototype sensors recorded transient effects in the atmosphere that were time correlated to gas injection boosts into the chamber. To our knowledge, these results were the first demonstration of a wind sensor integrated with electronics operating in situ in simulated Venus simulated conditions.

Other examples, including operation of a chemical species microsensor integrated with SiC electronics tracking sulfur dioxide (SO2) concentration in-situ for 60 days in Venus simulated conditions, will also be discussed. It is concluded that the overall maturity of these various technologies suggests that with continued development the capability for extended Venus surface exploration is viable in several years enabling a new paradigm in the measurement and understanding of the Venus surface.