AAE 450 Spring 2010 AAE 450 3/11/2010 Kathy Brumbaugh Chris Spreen

AAE 450 Spring 2010

Agenda AAE 450 Spring 2010 TimeActivity 9:45 am – 10 amFinal Design Review decisions 10 am – 10:10 amLooking forward… 10:10 am – 10:15 amQuestions & Concerns

Final Design Review decisions AAE 450 Spring 2010

Chris Spreen – Mission Design VVEES Res(2,1;3,1) optimal selected Interplanetary Trajectory Trajectory Comparisons rank Config.Res. Launch Date Launch Vinf (km/s) Sat. Arr. Date Sat. Arr. Time Vinf wrt Sat (km/s) Titan Arr. Date Titan Arr. Time Vinf wrt Titan (km/s) V at atm. (km/s) 1 optimalVVEES(2,1;3,1)3/31/ /29/ :14: /26/2046 6:14: selectedVVEES(2,1;3,1)3/21/ /12/20464:41: /10/20469:41: VVEES with Resonance Larger Launch Period (well beyond required 21 days) More trajectories within launch period (for use in case of launch slips)

AAE 450 Spring 2010 Ryan Garecht & Stephanie Sumcad Ballute Mass/Volume #’s  Ballute –Thickness: 35  m –Mass of Kapton: kg –Volume: 0.07 m 3  Gas –Mass: kg –Pressure: 10 Pa  TOTAL MASS –Ballute+Gas+Tanks+Tethers: kg – (3.7% mass fraction)

Ballute Operations  Sterilization: Not feasible to reach 490°C for 10s –Atmosphere too dense to capture into an orbit –Max rated temperature of material is 500°C –Sterilize on Earth  Fill mass flow rate and location  Packaging & deployment of ballute & tethers FRIDAY 2am!!!! Final Slides AAE 450 Spring 2010 Ryan Garecht & Stephanie Sumcad

Mission Completion Options: the Orbiter AAE 450 Spring 2010 Jeremy Moon – Trajectory Optimization Option I: Change semi-major axis, inclination angle to stabilize trajectory ΔV cost, lack of apparent stability solutions Option II: Use small impulse, Saturn perturbations to “rip” Orbiter from Titan orbit Unreliable solution, sensitivity Option III: Large impulse at apoapsis to escape Titan, stabilize about Saturn ΔV escape = km/s, large additional ΔV Option IV: Escape Titan, Saturn system on hyperbolic trajectory ΔV ≈ 6.3 km/s Option V: Sterilize Orbiter, allow Titan orbit to decay

Orbiter Termination AAE 450 Spring 2010 Jeremy Moon – Trajectory Optimization Equatorial orbits more stable than polar orbits → large inclination angle change required Saturn orbits extremely sensitive to initial conditions, require large ΔV Option V chosen: least ΔV, most reliable termination; sterilization concerns arise

AAE 450 Spring 2010 Lake Lander  Small heating coils  New Sub Probe Design Lake Lander, Alex Belshaw Jeremy Voight LocationMass (kg)Thickness (cm) Deck + Pontoon Sub-Probe Total7.4306N/A Catia by CAD members

Airship Gondola Insulation  Bleed heat to Science  *Power section arbitrary, Directing heat into blimp Thermal Control, Alex Belshaw AAE 450 Spring 2010 LocationMass (kg)Thickness (cm) Science Power*9.335 Total12.38N/A Catia by CAD members

AAE 450 Spring 2010 Airship  Lorenz, Ralph D. – A Review of Balloon Concepts for Titan[1]  Assuming –fixed heat transfer coefficient  ΔT = 20K (Superheat)  h = ~1 (W/m²-K)  Single-layer balloon wall  h can be reduced Airship FDR

Conclusions of Lorenz’s Analysis  “there is a theoretical maximum payload mass”  “… it is shown that an optimum balloon diameter exists – the maximum payload is achieved when the envelope mass and the payload mass are equal.”  Single-layer envelope wall  IF we reduce the gondola mass to 600kg from 1200kg (including seismic probes) AAE 450 Spring 2010

Diameter Unreasonable  Following Lorenz’s analysis  Diameter is large and inconsistent with simple Archimedes buoyancy balance.  Titan Explorer shows that for 1 RTG, payload mass is related to balloon diameter by an approximate slope of 25 kg/m [2] AAE 450 Spring 2010

Our Conclusions  A simple thermal resistance model predicts massive heat loss through envelope – 10 4 W; needed a better model  We need to significantly lower airship gondola mass. –To maintain same floating mass as originally planned –Airship and probes need to be 600kg (excluding balloon envelope)  We need to understand his assumptions and analysis before we proceed.  Perhaps pursue buoyant-gas alternative; although, Lorenz suggests that buoyant-gas vehicles are less efficient for large payload, low altitude missions  Balloon diameter will be about 44 m, for a 600kg payload; confirmed from 3 separately published papers [1-3] AAE 450 Spring 2010

Backup Slide  Heat transfer problem akin to warm-blooded animals where “heat loss area goes up as the square of size, but the energy storage volume goes up as the cube of size.” [1] AAE 450 Spring 2010 Reference  [1] Lorenz, R., “A Review of Balloon Concepts for Titan,” Journal of the British Interplanetary Society, Vol. 61, 2008, pp  [2] Leary, J., et. al., “Titan Explorer Flagship Mission Study,” NASA Planetary Science Division,  [3] ESA-SRE, “TSSM In Situ Elements,” NASA 2009.

AAE 450 Spring 2010 Orbiter Drop  Lake Landing –A = km^2 –Probability of landing in ellipse = 98% Entry =.7984 Earth G’s –Max Heating = 3.977e-5 W/cm^2 Landing = 5.5m/s Group Name (i.e.Trajectory Optimization)

Looking forward… Action Items Presentation #5 vs. Final presentation slides Paper template AAE 450 Spring 2010

TaskDescriptionDeadline Current design decisions To ensure everyone’s sanity, place all current decisions in one location with the most updated mass, power, dimensions and other useful quantities: ongoing Project/vehicle names Vote for names (top 5 for project, top 3 for each vehicle): MUVE6MA Go to VzhRRVNrY0E&hl=en for explanations and acronym descriptions VzhRRVNrY0E&hl=en Wednesday 5pm Final Design Review & Freeze Tasks & DescriptionDeadline Lake Lander numbers Enter final values for masses and volumes in “Subgroup mass breakdown” sheet: n NOW – Wed, 7:30pm Airship & Orbiter numbers Enter final values for masses and volumes in “Subgroup mass breakdown” sheet: n Thurs, 10pm Ballute Enter final values for masses and volumes in “Subgroup mass breakdown” sheet: n Thurs, 2am 3 rd stage & Fairing sizing Enter final values for masses and volumes in “Subgroup mass breakdown” sheet: n Fri, 4pm Over Spring BreakDeadline Section 1 Slides Slide 1 = most relevant information to final presentation. Rest of slides = final analysis with final numbers. May include back-up slides. Include images and pictorial descriptions! Sun 5pm Everyone- Report drafts Paper copies of report draft Thur, 9:30am Report drafts due to websiteFri, 5pm AAE 450 Spring 2010

Project timeline Final Slides: 1 st slide = most relevant information to final presentation Final analysis & summaries Back-up slides Paper drafts: See example paper Use figure, and table captions Cite references

Concerns AAE 450 Spring 2010