A Laboratory System for Simulation of Extreme Atmospheric Conditions in the Deep Atmospheres of Venus, Jupiter, and Beyond
Karpowicz, Bryan M.
Steffes, Paul G.
Hanley, Thomas R.
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A new atmospheric simulator, in operation and developed at Georgia Tech, now offers a flexible platform for simulating deep planetary atmospheres. In its current configuration, the laboratory system has been designed to simulate the deep Jovian atmosphere, and measure the microwave opacity of key atmospheric constituents. A 30 liter pressure vessel has been designed to withstand a pressure up to 100 bars of hydrogen, and helium with trace amounts of either ammonia or water vapor. A high temperature chamber along with the pressure vessel allows for simulations with a temperature ranging from 295-616 K. Within the pressure vessel a cylindrical microwave cavity is used to measure the microwave opacity of ammonia and water vapor. Two custom built feedthroughs allow us to excite, and measure absorption inside the simulator, while keeping a network analyzer (measuring wavelengths between 5 to 25 cm) at room temperature. The primary motivation for this system is to provide reliable microwave opacity models for use in interpreting data from the Juno microwave radiometer (MWR). The Juno-MWR will be capable of sensing centimeter-wavelength emission from the very deep atmosphere of Jupiter at pressures exceeding 100 Bars (Janssen et al., 2005, Icarus 171, 447-453). In order to accurately retrieve the abundances of microwave absorbing constituents such as ammonia and water vapor from measurements of the centimeter-wave emission from these deep layers, precise knowledge of the absorptive properties of these gases under deep atmospheric conditions is necessary. To date, only a very limited number of measurements have been made of the microwave absorption of ammonia or water vapor at such high pressures, and none of these measurements were conducted at wavelengths greater than 3.3 cm. While our primary motivation is to provide this critical information, this is not the only function our system may perform. In the future this system could easily be adapted to provide a test platform for instrumentation and hardware that must withstand some of the harshest atmospheric conditions, including those of Venus which has a surface pressure up to 100 bars. While the Venus surface temperature exceeds our maximum simulator temperature (616 K), it would certainly be a sufficient test platform for a variety of entry probe hardware for Venus, Jupiter or any other planetary atmosphere which reaches 100 bars pressure. This work is supported by NASA Contract NNM06AA75C from the Marshall Space Flight Center supporting the Juno Mission Science Team, under Subcontract 699054X from the Southwest Research Institute.