One-Thousand Leagues Beneath an Extraterrestrial Sea Titan Submarines, Boats, and Dropsondes: Concepts and Technologies Steven Oleson (NASA GRC), Ralph Lorenz (JHU/ APL), Michael Paul (JHU/APL), Jason Hartwig (NASA GRC), Justin Walsh (PSU/ARL) Compass Team NASA John H. Glenn Research Center, JHU/APL, PSU/ARL, Washington State U., New York University 1 FISO Telecon July 22, 2020 1 Titan Submarine Team Customer: NASA NIAC, Phases I & II, 2015-2018 • Concept PIs: Steve Oleson (NASA/GRC), Ralph Lorenz (JHU/APL), Michael Paul (JHU/APL), Jason Hartwig (NASA/GRC), Justin Walsh (PSU/ARL) • COMPASS Design Team – Lead - Steve Oleson – Science– Ralph Lorenz (APL) – System Integration, Conops, Launch vehicle – J Michael Newman – Mission – Steve McCarty – GN&C - Mike Martini – Hydrodynamics and Propulsion – Iskender Sahin (NYU), Shane Carberry Morgan (NYU), James Fittje – Mechanical Systems –John Gyekenyesi – Thermal - Tony Colozza – EDL – Evan Roelke (Georgia Tech) – Power - Paul Schmitz – C&DH, Software – Amee Bogner – Communications – Robert Jones – Configuration - Tom Packard – Cost – Tom Parkey, Elizabeth Turnbull • University Support – Washington State - Cryogenic Testing: Ian Richardson 2 2 Titan’s Seas Hundreds of lakes in the north, plus 3 seas : Kraken Mare, Ligeia Mare and Punga Mare (~1000km, 400km, ~200km across respectively). Only one large lake in the south, Ontario Lacus. 3 How Deep Are Ability of Cassini the Seas? radio waves to penetrate seas From Cassini Data: hints as use of RF for submerged Communications! ! Kraken and Ligeia in the north are the best Submersible Targets 4 When to Go: Seasons on Titan • If we want light to image the shore AND direct Earth Communica9ons Best to arrive in summer! (2045) • We can push to spring IF we have an orBiter for relay and suBmerge during ‘night’ (2040) • Trips to Saturn take 7 years or more so we need to launch early to mid 2030s 5 Earth vs. Titan Submarine Parameter Sea Horse UUV Titan Submarine Sea Material Water Liquid Ethane & Methane Density ~1000 kg/m^3 ~650 kg/m^3 / 450 kg/m^3 Temp ~0° to 30°C -178°C Viscosity 1000 uPa-s 200-4000 uPa-s Depth 1000s m 200 m sensed (design max set to 1000 m) Pressure by depth Every 10 m ~1 additional Bar Every 115m ~1 additional Bar Gravity 1 g 0.14g Size ~8m x 1m diameter with internal ballast tanks ~ 6m x .62m with external ballast tanks Mass ~4700 kg ~1200 kg Max Depth 1000 m (100 Bar pressure) 1000 m (~12 Bar pressure) Max Range 550km 5000 km Endurance 72 hours 1 year Speed 2 m/s 1 m/s (max) Power Battery Isotope (860W EOL) Navigation GPS (surfaced) & IMU Sun Sensor, Earth Tracking & IMU Communications Surfaced satellite ~ 800 km Surfaced Direct to Earth ~ 1.5 Billion km Payload Mass ~ 90 kg 6 6 Science • Titan is a target for the Must Do Ocean Worlds Explora9on Science Program Floor • Titan’s seas, while liquid methane Based, are a key part of a weather system like ours Added Science for Desired • Sampling Beneath the sea Baseline (especially the BoNom) could (intensive reveal sediment from Titan inves9ga9on of itself seabed) 7 7 Phase I Sub Concept: Big and Fast! • Autonomous Science Sonar, " Propulsion: Four motors for 1 m/s submerged and 1 m/s surfaced speeds in situ exploration, sampling of bottom sediment • Surface shore imaging and 90 day journey weather Kraken-1 • Two 430W • X-Band Comms direct to Earth Radioisotope Power (~800 bps during 16 hr DSN passes each Systems ~ 6 m long, ~ 1400 kg day surfaced) ~50 Mb per day " Thermal: Interior RPS heated, 3cm aerogel insulation, 300 W/m^2 thru skin, outer systems cryo capable (-178°C) " Navigation: IMU, sun direction, earth tracking, liquid velocity doppler, sonar scanning Power/Size/Mass/Aeroshell: Driven by DTE communications and 1 m/s speed Atlas 5 series using (efficient long narrow shape) and " Closed Ne system with an X-37 derived metal bellows ballast lifting body Science mass/hover needs, needs new tanks submerging and 8 aeroshell hovering down to 1000 m at pressures ~ 10 bar 8 Phase II Titan Turtle: Orbiter Supported " Propulsion: Four motors for • Autonomous Science 180 day Journey around/ 0.3 m/s submerged and 0.2 m/ Sonar, in situ exploration, beneath smaller Ligea Mare s surfaced speeds and sampling of bottom hovering sediment • Surface shore imaging and weather • Thermal: Internal RTG waste heat, 2.5cm aerogel insulation, Single 90W 300 W/m^2 thru skin ~ 2 m long, ~ 500 kg eMMRTG " Navigation using IMU, Orbiter UHF-Band Comms (~100 kbps during five, 30 minute tracking, sonar scanning 1500 km orbiter passes each day surfaced: ~ 1Gb/ SOA 4.5 m day) Aeroshell Providing orbiter relay (even when submerged!) and slowing speed to 0.2 m/s (delivered by " Pressure vessel with external, speed allows reducing mass by 3X and still orbiter) closed He system ballast tanks to providing same science investigations, allow for submerging and hovering smaller shape allows use of SOA 4.5m up to 200 m at pressures < 5 bar aeroshell 9 Phase II: Titan Boat with Dropsondes • Autonomous Science " Propulsion: Four motors for 0.1 m/s Sonar, in situ exploration w surfaced speeds 360 day Journey dropsondes around/beneath • Surface shore imaging and Single 90W EOL Kraken 1 and 2 weather eMMRTG • Boat with large radome to house phased (extended into array antenna and ensure self-righting after Ligeia) landing • Internal systems (including comms/ dropsondes) warmed by RTG waste • X-Band Comms heat, 1.5cm aerogel insulation, 200 W/ (~800 bps during m^2 thru skin) eight hour direct to " Navigation using IMU, sonar scanning, Earth ~ 3 m long, ~ 600 kg earth daily: ~ 30Mb/ SOA 4.5 m day) Aeroshell (delivered by Backing off to just Floor Science goals with cruisedeck) Boat/Dropsonde combination removes need • Battery Powered for ballast system, dropsondes use RF comm Dropsonde senses link to boat, Boat DTE communications allows stand-alone system, still allows use of P, T, Turbidity, SOA 4.5m aeroshell bottom image 10 Titan Submarines Side by Side Titan Design Sea(s) Science Size/ Power Speed/ Class Comms Ballast EDL Explored mass Submerged System FracCon Kraken I & II Desired Science ~ 6m Two, 500 W 1 m/s, 1/3 of Flagship DTE, ~ 50 Mb Ne Gas New, long Suite: ~ 100 kg, long, SMrling Mme submerged per day, with aeroshell surface, sea, BoDom ~1500 Radioisotope isolated insitu sampling, kg Generators metallic 90 day primary bellows Mission Ligeia Mare Desired Science: ~ ~ 2m Single, ~ 0.2 m/s, ½ Mme Works with Relayed Consumabl SOA 4.5 m 100 kg, surface, sea, long, 100W submerged OrBiter, part through e He gas aeroshell boDom insitu ~500 kg eMMRTG of Flagship? orbiter while with sampling, 180 day submerged, ~ conformal primary mission 1Gb per day Ballast tanks Kraken I & II Floor Science Suite: ~ ~ 3 m Single, ~ 0.1 m/s, only New DTE, ~ 30 Mb None SOA 4.5 m and Ligeia 80 kg with drop long, 100W dropsondes FronMers? per day aeroshell Mare if sondes, ~600 kg eMMRTG submerged accessable surface, sea, BoDom (Dropsondes science, BaDery ~ 30 Mb per day, 360 powered, day primary mission short duraMon) 11 Major Risks and Mitigations • Accuracy of Sea data/consistency from Cassini – MiMgaMon: • Develop potenMal sea mixtures and test • Design SuBmersiBles that minimize interacMons with seas (Consumable He or variable volume Ballast systems, dropsondes) • Propulsor operaMon in cryogenic sea – Analyses nearing compleMon to assess pressure drop effervescence impact on propulsion • Ballast Design/operaMon – MiMgaMon: Limit suBmersion to drop sondes or Test in relevant mixtures – Use of orBiter or Boat removes need to surface for comms/navigaMon • Thermal interacMon Between vehicle and sea (Liquid Methane/Ethane absorBs LARGE quanMMes of N2 – and Titan has a dense N2 atmosphere) – Thermally induced Effervescence: TesMng/Modeling show that when using RPS internally with Boat or suBmersiBle 300 Wth/m^2 will NOT create large amounts of BuBBles • CommunicaMons (cryogenic exposure to antennas, transmission through sea) – Cassini RF showed at least three of the seas radio transparent • NavigaMon (Sun/earth/BoDom tracking or navigaMon from orBiter) – Surface: Periodic updates using sun sensing, earth tracking should Be sufficient with IMU – SuBsurface: • IF available: Updates using RF tracking through orBiter or surface relay with IMU • If no RF sources available use BoDom tracking and surface periodically 12 Bubble Incipience Data - Bubble incipience data taken at WSU - Hot plate submerged in various bubbly mixtures - Sub waste heat flux is ~380 W/m2 - Bubble Incipience data taken shows we have a margin of safety of ~3 on thermal side. - Need to run subscale propulsor tests to rule out pressure-driven effervescence Heat Flux at N Sea Data CH C H 2 Pressure Heater Surface Bubble 4 2 6 [mol Temp. Point [mol %] [mol %] [bar] Temp. [K] Incipience [W/ %] [K] m2] 1 87.1 0.0 12.9 1.546 96.2 101.4 10830 2 87.7 0.0 12.3 1.65 93.5 100.2 13029 3 82.5 0.0 17.5 1.782 95.9 99.6 3257 4 72.3 0.0 27.7 4.53 97.0 104.1 17915 5 0.0 97.3 2.7 1.73 103.6 118.7 28810 6 0.0 94.6 5.4 4.41 92.5 107.2 24559 7 50.6 44.2 5.2 1.85 97.8 108.7 18729 8 57.5 37.2 5.3 1.561 92.7 107.8 26448 9 47.6 30.9 21.5 3.21 91.9 97.8 11074 10 24.9 48.3 26.8 3.44 91.9 94.2 2475 11 27.0 61.4 11.6 3.85 91.8 98.8 10244 12 30.2 63.9 5.9 2.133 93.6 111.6 31758 1 13 3 <7 TRL by Design Item Phase I Stand-alone Sub Phase II Orbiter Supported Phase II Ship/Dropsondes Vehicle Level 2-3 2-3 2-3 Science Instruments 3-4 External Cryogenic Science 3-4 External Cryogenic Science 3-4 External Cryogenic Science Instruments Instruments Instruments AD&CS 4 (suBmerged navigaMon using 4 (external sensors,