. Kraken Mare Exploration - Missions Scenarios... Balloons, Space Planes, Rovers and Other

Note: Methane is the primary ingredient in many of Saturn’s moon’s lakes and seas. Scientists have designed a submarine that can withstand the volatile chemicals that will be found in these methane lakes.

Spacecraft/Submarine Hybrid Could Explore Titan's Methane Seas

Credit: Science Channel

. Mission Concept At TITAN: In 2038, that will be the mission to Kraken Mare Sea with a... Submarine!
. Mission Timeline 



Graphic surface and subsurface of TITAN

Last Look of Titan by Cassini, Sept 2017

Impact Site on saturn of the Cassini Orbiter - Last Image, Sept 15, 2017

Nasa 360 talks - titan submarine

othersMissions concepts at titan


Kraken Mare Exploration – Mission Scenario

Once afloat, the submarine deploys its mast with the X-band Omni antennas, its MET and its surface imaging system. With its Sun sensor data, it obtains a lock on Earth and communicate its position and health status via one of the Omni antennas. A low-rate beacon is then activated. Contact with Earth last for approximately 16 hr.
During its first communications, the sub play back entry-decent-splashdown (EDS) data and system-wide housekeeping data. In the same time, it returns its first measurements of wind and current sea speed, air and sea temps from the MET and show its first images from Kraken Mare.
With these data received, Earth perform a health check to assess hull integrity and system-wide thermal balance.
The sub activate is depth sonar and track the aero-vehicle as it sinks to the bottom of Kraken Mare. The main goal is to providing the first measurements of subsurface currents as well as the local depth of the Mare.
Before the end of that period, the sub stay in a safe hold, listening for communications with Earth. During these periods through the course of the mission, several different holding patterns while out of contact with Earth may be evaluated. For this purpose, it is instructed to drive at a slow speed in a box pattern, gathering data until time has elapsed. The sub holds relative position and perform meteorological measurements, as well as sea composition and current measurements. Once contact with Earth is re-established via the omni, the phased array antenna is used to relay science data gathered.
Next day, the submarine runs through sea trials to prepare its operations. The propulsions run at low speed and any vibration feedback monitored. During this time, there is no expectation of making headway. Once the low speed testing is complete, the propulsion system is fully engaged and the sub begins surface drive.
Steady-state surface travel includes sonar tracking of the bottom to determine depth variation across the Mare. IMU calibration is done. Wind speed, air and sea temps, sea state and current speed (MET) data are taken.

Titan Submarine driving on the surface of Kraken Mare

At days three and four, we pasts to the next level of sea trials and push the sub at a maximum drive speed test to determine the controllability. Maximum surface speed is 0.9 m/s (3 ft/s), assuming 100W propulsion power. The limit on the surface speed is due to the power available to the propulsions. When this is done, we do an emergency test. The lion share of power available from the SRG’s is required for the communications system. The minimum speed that the sub can sail at while maintaining positive steerage also be assessed.
After surface trials are complete, diving and surfacing trials will begin. The sub will be instructed to submerge and surface using the propulsions. A moderate dive/surface angle of the sub body of 10° would result in a rate of depth change of 0.17 m/s (0.6 ft/s). Once submerged, undersea driving would be done at a maximum submerged speed of 1.6 m/s (5.2 ft/s). The subs main computer would autonomously determination the trim required for undersea driving.
First Transit
With the final commissioning tests complete, the sub would begin its first leg of transit on its scientific mission. The first submerged leg of the transit would be limited to approximately 2 hr. Periodic sonar and liquid composition measurements would be taken and bottom sampling accomplished. The sub would then surface and re-establish contact with Earth via the DSN. A quick-look at the first long-duration transit would be done on Earth to verify that all was well on the sub, and then the sub would continue underway.
The first shoreline imaging would be conducted during the initial transit (Figure 3.19). The initial transit would cover approximately 200 km (124 mi) over a period of 61.7 hr of continuous propulsor operation taking 7 Earth days with 16 hr of downlink each Earth day. Atmospheric sensing and weather measurements by meteorology sensors would be gathered during surface driving.

Shoreline imaging during the first transit of the Titan Submarine

Primary Mission
The next leg of the primary mission would transit the sub 400 km (248 mi) over a period of 14 Earth days to the estuary of Ligeia Labyrinth. The goal is to 'sniff' whether there is a composition gradient driven by methane-rich flow from Ligeia. The sub would remain in the area through 24 Earth days (1.5 Titan days) of tidal monitoring to see how the cycle repeats. During the period, the sub would perform small transits and returns, then drift for a few hours at a time and measure displacement via imaging and sonar.
With the measurements at Ligeia complete, the sub would transit over a 14 Earth day period through Kraken Mare around the shoreline of Mayda Insula. The sub would perform detailed shoreline imaging, detailed bottom mapping and periodic bottom sampling.
Continuing along the shoreline, the sub would then perform tidal monitoring in a Strait for another 14 Earth day period (Figure 3.20). The sub would stay in the strait for a tidal cycle, performing small transits and returns followed by a drift of a few hours at a time to measure displacement via imaging/sonar. Detailed bottom mapping, detailed shoreline imaging (both mainland and islands) and periodic bottom sampling would be conducted.
The sub would proceed to the Throat of Kraken and would loiter in the area for a 14 Earth day period. Once again, the sub would remain in the strait area for a tidal cycle. Small transits and returns are performed, and then the sub would drift for a few hours at a time and measure displacement via imaging/sonar. Detailed bottom mapping and periodic bottom sampling would be done, as well as detailed shoreline imaging. This would represent the end of the sub’s 90 day primary mission but it would still have substantial power available to continue its explorations for extended missions.
During an extended ninety day mission, the submarine would transit the throat of Kraken and perform similar explorations in other areas of Kraken Mare. Once this half year of exploration is completed the submarine could be tasked to revisit points of interest and perhaps do a complete sonar mapping of the seas. All in all, the submarine could explore over 3,000 km (1,864 mi) at an average speed of 0.3 m/s.
At some point, though, the output of the submarine’s power plants would reach a level where sea travel is no longer feasible and it would truly reach its EOM state (Figure 3.21). The sub would be run aground so that the nuclear material in the SRG’s remains contained within the sub. This would mitigate the risk of the sub sinking to a depth where the hull could be compromised and nuclear material could be released into the Mare.

Investigating Bayta Fretum Strait to the south of Mayda Insula

The Titan Submarine is grounded when mission is complete

NASA/TM—2015-218831 / Phase I Final Report: Titan Submarine / Steven R. Oleson - Glenn Research Center, Cleveland, Ohio / Ralph D. Lorenz - Johns Hopkins University, Applied Physics Laboratory, Laurel, Maryland / Michael V. Paul - The Pennsylvania State University, Applied Research Laboratory, State College, Pennsylvania / July 2015

Titan Submarine: Exploring the Depths of Kraken Mare / Jason Hartwig, Anthony Colozza, Steve Oleson, Geoff Landis, Paul Schmitz - NASA Glenn Research Center / Ralph Lorenz - Johns Hopkins University, Applied Physics Lab / Michael Paul & Justin Walsh - Penn State University, Advanced Research Lab / 26th Space Cryogenic Workshop, June 25, 2015

Mission Timeline / www.nasa.gov

NASA Innovative Advanced Concepts - NIAC

Launch 2038 Trans-Titan/ Insertion

Interplanetary Cruise ~7 Years

Titan Atmospheric / Entry & Descent ~2.5 hours Kraken Mare Splashdown

Sub Activation & Checkout ~4 days

First Transit ~7 days

Map and Explore Kraken-1 ~90 days

Map and Explore Kraken-2 ~90 Days

Return to Ligeia/Mare and enter if possible ~120 Days

End Of Primary Mission

Cruise Day: • 8 hrs Submerged Science/Transit • 16 hrs Surfaced shore imaging/meteorology/data return

Phase II Study Plans

The following is summary of conceptual design activities that would be conducted under a Phase II NIAC study
• Examine Science Payload in more detail (e.g., immersion-tolerant meteorology package; seabed sampling options, etc.)
• Evaluate subsurface communication DTE, and via Relay orbiter, noting RF transparency of some Titan liquids
• Evaluate impact on CONOPS and downlink data benefit of a relay orbiter, identify most useful complementary science from orbiter (e.g., could a space borne radar detect the sub or its wake?)
• Create a conceptual design of the aero-vehicle/Titan entry system and create a MEL for that system
○ Develop the details of SRG installation accommodations, procedures and GSE required
○ Assess thermal protection system capability to withstand Titan entry heating
○ Assess sub mounting in aero-vehicle
○ Assess systems for separation of aero-vehicle from sub after Titan splashdown
○ Assess detailed LV interfaces including LV adapter
• Perform trajectory design to determine LV performance requirement, transit time to Titan, and any necessary planetary gravity assist maneuvers required to assure sub arrival at Titan summer
• Assess other Titan entry systems based on entry speed and heating
○ Inflatable heat shield/decelerator
• Assess alternative methodologies for Titan descent and splashdown
○ Circular chutes and guided parasail landing system
• Assess alternate sub deployment schemes from entry system
○ Sub separation after splashdown
○ Sub separation before splashdown (separate splashdowns of sub and entry system)
• Assess required targeting to assure landing on Kraken Mare
• Analyze communications systems requirements for the trans-Saturn cruise phase, and the Titan EDL phases of the Titan Submarine mission
• Perform basic physics testing of liquid ethane saturated with nitrogen to evaluate the ‘effervescence’ issue.