{{Short description|Proposed NASA submarine to land on Titan}} {{distinguish|Titan (submersible)}} {{Infobox spaceflight | name = Titan Submarine | image = Titan Submarine artist depiction.webp | image_caption = Artist's depiction of the submarine | mission_type = [[Reconnaissance satellite|Reconnaissance]] and [[submarine]] | operator = [[NASA]] | launch_date = 2030s-2040s | dry_mass = 500 kg<ref name="MikeWall2020" /> | dimensions = 20 by 6.5 ft<ref name="MikeWall2020" /> | landing_date = 2040-2045 | landing_site = [[Kraken Mare]] or [[Ligeia Mare]] }} [[File:PIA17655 crop Titan north polar seas and lakes.jpg|thumb|[[Synthetic aperture radar]] mosaic of [[Titan (moon)|Titan]]'s north polar region showing Titans largest lakes [[Kraken Mare]], [[Ligeia Mare]], and [[Punga Mare]] ]]
'''Titan Submarine''' is a proposed unmanned NASA [[submarine]] probe that will visit [[Saturn]]'s largest [[Moons of Saturn|moon]] [[Titan (moon)|Titan]], and will explore either [[Kraken Mare]] or [[Ligeia Mare]], two of Titan's [[Lakes of Titan|lakes]]. The concept was proposed by Steven Oleson, [[Ralph Lorenz]], and Micheal Paul, technical experts at the [[Glenn Research Center]] in Ohio.<ref name="MikeWall2020">{{cite web |last1=Wall |first1=Mike |title=Submarine could explore seas of huge Saturn moon Titan |url=https://www.space.com/saturn-moon-titan-submarine-concept-mission.html# |website=[[Space.com]] |access-date=14 April 2024 |date=27 August 2020}}</ref>
==History== In early 2005, studies conducted by the [[Cassini–Huygens|Cassini-Huygens]] probe revealed [[organic compound|organic compounds]] in the [[atmosphere of Titan]], raising the possibility of [[life on Titan]].<ref>{{Cite web|url=https://www.afdc.energy.gov/fuels/fuel_properties.php|title = Alternative Fuels Data Center: Fuel Properties Comparison}}</ref><ref>{{cite news |last1=Vandel |first1=Omri |title=All the answers to the question is there life in space? |url=https://www.ynet.co.il/articles/0,7340,L-3465434,00.html |newspaper=Ynet |access-date=14 April 2024 |date=29 November 2007}}</ref> During its 2-hour descent, [[Huygens (spacecraft)|Huygens]] provided data about Titan's atmosphere, with information suggesting a functioning [[climate system]], [[water cycle]], and the presence of [[organic matter]] and molecules.<ref>{{cite web |last1=Moskowitz |first1=Clara |title=Exotic Life Could Sprout From Titan Chemistry |url=https://www.space.com/6886-exotic-life-sprout-titan-chemistry.html |website=[[Space.com]] |access-date=14 April 2024 |date=25 June 2009}}</ref>
On July 22, 2006, the Cassini-Huygens probe conducted a flyby of Titan, passing at a distance of 148,000 km.<ref>{{cite web |title=Outbound View |url=https://www.jpl.nasa.gov/images/pia08246-outbound-view |website=[[Jet Propulsion Laboratory]] |access-date=14 April 2024 |date=18 August 2006}}</ref> The flyby revealed methane lakes on the surface of Titan, providing evidence of the existence of liquid water, a hypothesis first suggested by a [[Hubble Space Telescope]] observation of Titan in 1995.<ref>{{cite web |title=Hubble Observes Surface of Titan |url=https://www.jpl.nasa.gov/images/pia01465-hubble-observes-surface-of-titan |website=[[Jet Propulsion Laboratory]] |access-date=14 April 2024 |date=26 September 1998}}</ref>
Following these discoveries, the [[NASA Institute for Advanced Concepts|Institute for Advanced Concepts]] proposed the [[Titan Mare Explorer]]. However, the proposal was superseded in a 2012 vote by the [[InSight]] lander, which was tasked with studying the core of Mars.<ref>{{cite news |url=https://www.washingtonpost.com/national/health-science/nasa-will-send-robot-drill-to-mars-in-2016/2012/08/20/43bf1980-eaef-11e1-9ddc-340d5efb1e9c_story.html |title=NASA will send robot drill to Mars in 2016 |newspaper=Washington Post |first=Brian |last=Vastag |date=August 20, 2012 }}</ref> However, both the Titan Mare Explorer and the Titan Submarine projects remain active under the auspices of NIAC.
The Titan Submarine initiated Phase I in 2014 and transitioned to Phase II, dubbed "Titan Turtle", in November 2020. The Titan Submarine is still under development by NIAC.<ref name="LouraHall2014">{{cite web |last1=Hall |first1=Loura |title=Titan Submarine: Exploring the Depths of Kraken |url=https://www.nasa.gov/general/titan-submarine-exploring-the-depths-of-kraken/ |website=[[Nasa.gov]] |access-date=14 April 2024 |date=14 June 2014}}</ref>
==Overview== The submarine will be launched aboard an [[Atlas V]] rocket, accompanied by a [[Boeing X-37]], which is designed to withstand the [[climate of Titan]].<ref>{{cite web |title=תוכנית נאס"א: לשגר צוללת לחלל עד 2040 |url=https://www.ynet.co.il/articles/0,7340,L-4626313,00.html# |website=ynet.co.il |publisher=Ynet |access-date=19 December 2024 |date=13 February 2015}}</ref>
The Titan Submarine will be equipped with [[radioisotope rocket]]s, a type of [[thermal rocket]] that uses [[Radioactive decay|decaying radioactive]] elements, to propel the submarine for longer durations on Titan while conserving power on the probe. Radioisotope rockets utilize [[isotope]]s such as [[polonium-210]] or [[plutonium-238]], each of which have a [[half-life]] of approximately 138 days or 80 years respectively (plutonium-238 provides a stable output over a much longer span whereas polonium-210 provides 250 times more thermal energy but for a far shorter lifespan).<ref name="MikeWall2020" /><ref>{{Cite conference |last=LeMoyne |first=R. |date=September 2006 |title=Fundamental Analysis of Radioisotope Propulsion |url=http://arc.aiaa.org/doi/10.2514/6.2006-7272 |conference=Space 2006 Forum |publisher=American Institute of Aeronautics and Astronautics |doi=10.2514/6.2006-7272 |isbn=978-1-62410-049-9 |id=AIAA 2006-7272|url-access=subscription }}</ref> It will also be equipped with a sampler to collect samples of lakebed minerals and liquid methane and ethane hydrocarbons from the water on Titan. Additionally, a camera will be attached to the front of the vessel.<ref name="MikeWall2020" />
== Scientific goals == [[File:Model of the Titan Submarine.png|thumb|Model of the Titan Submarine]] The submarine will aid scientists in refining models and simulations of undersea activity on Titan. It will contribute to the detection of elemental and chemical properties of the water, as well as undersea rocks and minerals. Additionally, it may help identify [[Submarine earthquake|undersea seismic activity]] on Titan. The submarine will also collect data on the depth and temperature of specific locations within lakes.<ref name="LouraHall2014" />
Additionally, theories propose the existence of a global [[subsurface ocean]] beneath Titan's surface. The mission aims to enhance understanding of subsurface oceans and explain the dramatic shifts in Titan's surface features. It may also provide insights into the impact of subsurface oceans on the geology beneath and above Titan's seas.<ref>{{cite web |title=Ocean may exist beneath Titan's crust |url=https://www.esa.int/Science_Exploration/Space_Science/Cassini-Huygens/Ocean_may_exist_beneath_Titan_s_crust |publisher=[[European Space Agency]] |access-date=19 December 2024 |date=25 March 2008}}</ref>
During certain parts of the mission, the submarine will partially emerge from the water to study the weather, tides, coastlines, and the unsolved observation surrounding disappearing islands or icebergs on Titan.<ref>{{Cite news |last1=Kahan |first1=Raphael |last2=Elam |first2=Harel |date=16 February 2015 |title=ים של כוכבים: נאס"א שולחת צוללת לטיטאן |url=https://www.calcalist.co.il/articles/0,7340,L-3652558,00.html |access-date=14 April 2024 |work=[[Calcalist]] |language=he}}</ref>
==Instruments== ===Instrument list=== *Liquid samplers *Surface imager *Depth sounder *Weather sounder *[[Side-scan sonar]] arrays<ref name="MikeWall2020" />
====Interior instruments==== *Command and data handling *Communications *Altitude determination and control<ref name="LouraHall2014" />
====Proposed instruments==== *Seafloor sample analyzer *Ventral imager<ref name="MikeWall2020" />
====Energy==== The submarine will be equipped with 840 W of: *[[Radioisotope thermoelectric generator|Isotope power systems]] *[[Stirling radioisotope generator]] *2 [[Stirling radioisotope generator|eight-GPHS SRG]] (chosen as the baseline power system proving 900 W of DC power)<ref>{{Cite journal |last1=Hartwig |first1=J. W. |last2=Colozza |first2=A. |last3=Lorenz |first3=R. D. |last4=Oleson |first4=S. |last5=Landis |first5=G. |last6=Schmitz |first6=P. |last7=Paul |first7=M. |last8=Walsh |first8=J. |date=March 2016 |title=Exploring the depths of Kraken Mare – Power, thermal analysis, and ballast control for the Saturn Titan submarine |url=https://www.sciencedirect.com/science/article/pii/S0011227515001162 |journal=Cryogenics |series=2015 Space Cryogenics Workshop, June 24–26, 2015, Phoenix, AZ Hosted by NASA Glenn Research Center, Cleveland, OH, USA |volume=74 |pages=31–46 |doi=10.1016/j.cryogenics.2015.09.009 |bibcode=2016Cryo...74...31H |issn=0011-2275|url-access=subscription }}</ref><ref>{{cite web |last1=David |first1=Leonard |title=NASA Space Submarine Could Explore Titan's Methane Seas |url=https://www.space.com/28589-titan-submarine-robotic-saturn-ship.html |website=[[Space.com]] |access-date=14 April 2024 |date=18 February 2015}}</ref>
==References== {{reflist}}
==Further information== *[https://www.youtube.com/watch?v=NnKxbdpLP5E YouTube video] gives an illustration on how the variety of instruments on board the submarine work.
{{Titan}} {{Saturn spacecraft}}
[[Category:Research submarines of the United States]] [[Category:Cancelled NASA space probes]] [[Category:Missions to Titan (moon)]]