The Titan Submersible Explorer: A First Order Evaluation of Concept, 18-R9824

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Principal Investigators
Joseph E. Crouch
Benjamin K. Miller
Timothy G. Brockwell
Jody O. Cronenberger
Michael E. Epperly
Steven T. Green
Jeremy R. Pruitt

Inclusive Dates:  05/21/08 – 09/21/08

Background - The National Aeronautics and Space Administration (NASA) and the European Space Administration (ESA) are in the process of selecting the next outer planets flagship mission, which will be developed over the next decade. Two candidate missions are under consideration, a Titan Saturn System Mission and a Europa Jupiter System Mission. Early next year NASA and ESA will use research results from work currently being conducted to select one of these missions for further development.

Discoveries from the Cassini-Huygens mission, supported by NASA and ESA, indicate that a number of large liquid hydrocarbon lakes exist in the polar regions of Titan. These findings are significant as they present the first evidence for an "open" stable body of liquid anywhere other than earth. The largest of these, Lake Kraken Mare, covers approximately 40,000 square miles.

The Titan Submersible Explorer (TSE) is a simple concept that, when implemented, will enable scientists to investigate one of Titan's lakes. Similar to the Huygens probe, the TSE will be targeted by the Saturn Orbiter, released to enter Titan's atmosphere, and descend into one of the larger lakes. Once in the lake, the battery-powered TSE will accomplish two primary tasks: 1) evaluate chemistry at the surface of the lake, and 2) evaluate chemistry at the bottom of the lake. Evaluating chemistry at the lake's bottom is important because thermal venting may exist. This venting could provide an environment that supports formation of organic compounds. Once the TSE has completed bottom analysis it will release its buoyancy control module and return to the surface of the lake. On the surface it will transmit its data back to the orbiter.

Approach - It was recognized that limited funding, time and assets would constrain research efforts. Mission conditions, associated hazards and mitigation concepts were quantified. This was accomplished as follows: 1) research conducted to establish TSE mission goals; 2) identification of science package, vehicle, and support systems attributes; 3) research conducted to validate baseline assumptions, identification of "cause and effect" for mission-inherent risks, and identification of probable means of mitigation; and 4) assembly of findings into a technology requirements package. An effective research approach was invoked, based on known information and assumptions.

Accomplishments - Results of this study indicate that the Titan Submersible Explorer (TSE) concept is viable and that all major design challenges can be overcome. The TSE is a simple concept (Figures 1, 2 and 3). Deploying a submersible probe into one of Titan's hydrocarbon seas or lakes presents a number of unique design challenges. SwRI briefly examined two additional analysis options for the TSE mission: 1) lake sediment sampling, and 2) Titan atmospheric sampling. While they add technical complexity, both options are viable and offer notable scientific benefit.

Figure 1. TSE Conceptual Layout (not to scale)
Figure 2. Entry and Atmospheric Descent

Figure 3. TSE Maximum Depth vs. Science Payload Mass

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