Long-Lived Venus Lander Conceptual Design: How to Keep It Cool

Abstract

Surprisingly little is known about Venus, our neighboring sister planet in the solar system, due to the challenges of operating in its extremely hot, corrosive, and dense envirorunent. For example, after over two dozen missions to the planet, the longest-lived lander was the Soviet Venera 13, and it only survived two hours on the surface. Several conceptual Venus mission studies have been formulated in the past two decades proposing lander architectures that potentially extend lander lifetime. Most recently, the Venus Science and Technology Definition Team (STDT) was commissioned by NASA to study a Venus Flagship Mission potentially launching in the 2020-2025 time-frame; the reference lander of this study is designed to survive for only a few hours more than Venera 13 launched back in 1981! Since Cytherean mission planners lack a viable approach to a long-lived surface architecture, specific scieutific objectives outlined in the National Science Foundation Decadel Survey and Venus Exploration Advisory Group final report cannot be completed. These include: mapping the mineralogy and composition of the surface on a planetary scalej determining the age of various rock samples on Venus, searching for evidence of changes in interior dynamics (seismometry) and its impact on climatej and many other key observations that benefit with time scales of at least a full Venus day (Le. daylight/night cycle). This report reviews those studies and recommends a hybrid lander architecture that can survive for at least one Venus day (243 Earth days) by incorporating selective Stirling multi-stage active cooling and hybrid thermoacoustic power. i 80

Power System Options for Venus Exploration Missions: Past, Present and Future

“…Up to date, Venus surface landers had an average operational lifetime in the order of a single hour. The longest-lived lander was the Soviet Venera 13, and it only survived two hours on the surface (Dyson et al 2009). The limiting factor, however, was not the power system or the installed battery capacity, but the fact that the landers simply were not designed to survive the corrosive, high-temperature and high-pressure surface conditions for much longer.…”

“…Radioisotope generators were thus considered as power source for operating a Stirling-cycle cooling system designed to outbalance the heat leak in from the environment, for instance (Dyson et al 2009). Studies for designing a lander architecture capable of surviving at least one Venus day (this equals roughly 243 terrestrial days) by applying Stirling-cycle cooling are available and prove that, in theory, landing systems can be operated with extended operational lifetime (Dyson et al 2009). Such a scenario is far more challenging in terms of power system design than the short-lived descent and landing elements applied up to date.…”

“…The VEGA landers resembled the Venera 9-14 lander, and thus did not survive significantly longer than the Venera landers, each operating for nearly one hour (Dyson et al 2009). The batteries installed in the balloons are assumed to be the lifetime limiting factor of these unique atmospheric exploration systems.…”

Terrestrial applications of extreme environment stirling space power systems

“…5. In this configuration both the power and cooler are based on the Stirling cycle and two-stage cooling is employed [1]. The challenge for a location such as on the surface of Venus is to design a Stirling convertor that can operate at temperatures exceeding 1050°C on the hot-end in order to reduce the quantity of Plutonium-238 required (see Table II).…”

“…Recently, NASA GRC began the development of a combined power and cooling system that is intended to operate in very high temperatures while providing the cooling protection necessary for sensitive components [1]. Specifically, three new Stirling Duplex systems were designed based on thermoacoustic, free-piston Stirling, and a novel free-displacer Stirling concept; a new extreme environment testing chamber was constructed for Technology Readiness Level 6 demonstration; a new five feature variable conductance heat pipe was demonstrated that enables multiple stops and restarts of the RPS system [2]; and a novel Stirling convertor with no moving parts was proposed.…”