Research Blog 2: Unmanned Maritime Systems

In this module, you will create a blog post about an article centered on the future of UMS in either the military or civilian sectors.


What is Beneath the Seas of a Distant, Not-so-distant World?

In the not so distant future of 2047, NASA has plans to explore Titan, the amazing moon of Saturn. Titan is the only other planetary body, besides Earth, within our solar system that has large lakes and seas of liquid on the surface. The atmosphere on Titan even experiences the hydro-cycle of evaporation, condensation and rain. The major difference however, is the hydro-cycle of Titan involves liquid methane and ethane instead of water. (O’Neill, 2015) In 2004, NASA’s Cassini spacecraft arrived at Saturn and began studying the moon. In 2005, the Huygens probe landed on the surface of Titan and gave us our first real look at a shoreline on another planet. (David, 2015) However, the human desire to know more drives us to wonder what is beneath the waves of Titan. The solution is deploy an autonomous submersible.

During the NASA Innovative Advanced Concepts 2015 Symposium (NAIC), Steve Oleson, head of NASA’s Collaborative Modeling for Parametric Assessment of Space Systems (COMPASS) unveiled the plan for a submersible designed to explore Titan’s largest lake, the Kracken Mare. The mission would combine surface and subsurface capabilities in a traditional tube platform. Much of the technology would be adapted from terrestrial submersibles, side-scan sonar, environmental sensors, depth sounders, lights, cameras and communication systems. (O’Neill, 2015) However, there will be adaptations. Noon on Titan is as bright as approximately ten minutes after sunset on a typical Earth day. (NASA, 2015) The low intensity is not enough to charge solar cells; nor would solar cells be the best choice for submersible energy. Instead, the submersible would generate power using the same technology as other extra-planetary systems like Cassini and the Mars rover Curiosity. Two Stirling radioisotope generators would power the submersible by creating electricity from the heat generated by plutonium. (NASA, 2015)

The technology to deliver the submersible would also be different and is still very much in the theory state. Suggestions include a lifting body spacecraft and even an inflatable aeroshell. (David, 2015) There is hope of more study in the future that would include a solar sail transport to minimize transit time. Cassini took seven years to reach Saturn because the weight of six tons was too great for the launch system to heave it that far out into space. The Titan submarine would weigh approximately one ton, well within the NASA limits of 90,000lbs per payload, but the distances is still the same. It requires a lot of energy to go that far.  (NASA, 2015)

Another important adaptation is propulsion. To say the methane seas of Titan are cold is an understatement. Temperatures are estimated to be around 90 degrees Kelvin (-298 degrees Fahrenheit); too cold for terrestrial propulsion systems. As an alternative, scientists are looking to develop a piston-driven system that would utilize nitrogen as ballast. (O’Neill, 2015) A blueprint was presented by the COMPASS team at the NAIC of a system that would allow for repeated deep dives and surfacing of the submersible. (David, 2015)

The planned seafaring mission would be about 90 days, covering approximately 2000 kilometers and would travel on the surface and below. The submersible would have to manage large waves, tides and other unknowns. (David, 2015) Sensors on Cassini have been able to survey the lakes of Titan to a depth of 200 meters, their limit of exploration. (O’Neill, 2015) What still remains to be discovered is the chemical composition or dilution of the lakes and seas as well as, do temperatures, composition and density change with depth like on Earth? (David, 2015)

The exploration of Titan is an amazing endeavor. If the decision is favorable to pursue the mission, a submarine is the best way to explore the seas of this distant world. It decreases the risks involved in using an airborne system dropping a tethered sensor beneath the surface and increases the overall distance the probe could potentially travel in the timeframe allotted by the mission. The choice of the tube platform over other submersible platforms used for terrestrial exploration, as the mechanism also increases maneuverability and allows for more sensors onboard giving the most benefit for the investment. I agree with the findings of the COMPASS team and the mission to study Titan’s Kracken Mare. The technology being studied and reviewed would also be of tremendous benefit to terrestrial autonomous underwater vehicles.

References

David, L. (2015, February 18). Robotic Submarine Could Explore Seas of Saturnu0027s Moon Titan | Space.com. Retrieved August 27, 2015, from http://www.space.com/28589-titan-submarine-robotic-saturn-ship.html

NASA, (2015 March 5) Titan Submarine. Retrieved on August 27, 2015 from https://new.livestream.com/viewnow/NIAC2015/videos/75333785

O’Neill, I. (2015, February 12). NASA Wants to Send a Submarine to Titan’s Seas. Retrieved August 27, 2015, from http://news.discovery.com/space/alien-life-exoplanets/nasa-wants-to-send-a-submarine-to-titans-seas-150212.htm

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