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SDO Preliminary Design Review: Propulsion Subsystem

SDO Preliminary Design Review: Propulsion Subsystem. Gary Davis / Propulsion Subsystem Lead Propulsion Team Members: Jon Lewis / Flight Hardware Mark Mueller (Aerospace Corp.) / Analysis Support

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SDO Preliminary Design Review: Propulsion Subsystem

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  1. SDOPreliminary Design Review:Propulsion Subsystem • Gary Davis / Propulsion Subsystem Lead • Propulsion Team Members: • Jon Lewis / Flight Hardware Mark Mueller (Aerospace Corp.) / Analysis Support • SPERT Review Team Apurva Varia / Analysis • Mike Wilks / Technician Dewey Willis / Propulsion I&T

  2. Propulsion Functional Requirements (1/2) 1)Tipoff rate nulling • Use ACS thrusters in on-pulsing mode • Must be ready within 15 minutes of separation • Only necessary for large tipoff rates • 2) Main engine firing getting to GEO • Bi-propellant main engine fires in steady-state mode • ACS thrusters provide 3-axis control in on-pulsing mode • Contingency backup mode uses ACS thrusters only

  3. Propulsion Functional Requirements (2/2) 3) ∆H and ∆V on orbit • ∆H using ACS thrusters in on-pulsing mode • ∆V using ACS thrusters in off-pulsing mode • 4) Disposal out of GEO • Use ACS thrusters to raise orbit to minimum for disposal • Burn all propellant possible through ACS thrusters • Vent propellant tanks

  4. Propulsion Design Overview • Bi-propellant system • Oxidizer: MON-3 Nitrogen tetroxide (NTO) • Fuel: Monomethylhydrazine (MMH) • Single bi-propellant main engine provides thrust for orbit raising • 445 N (100 lbf) class main engine • Eight bi-propellant ACS thrusters provide control and stationkeeping thrust • 22 N (5 lbf) class ACS thrusters, canted at 10° for 3-axis control • Grouped in two redundant sets • Thrusters can be used to back up the main engine • Two 1.07 m [42 ”] diameter spherical propellant tanks • Propellant management devices (PMDs) provide gas-free propellant delivery • Bi-propellant system allows identical fuel and oxidizer tanks • Common helium pressurization system • Two Composite Overwrapped Pressure Vessels (COPV) store helium pressurant • Pressure regulators feed helium to the propellant tanks • Series redundant check valves isolate propellant during orbit raising maneuvers • Pyrotechnic valves used for isolation • Pressurant and propellant tanks isolated before launch • Pressurization system and main engine isolated after reaching GEO

  5. Thruster Layout Changes Since SCR • Removal of “forceless torque” and maneuver orientation requirements allowed for a simpler thruster configuration Is Was Sketches only, not to scale! (Main Engine not shown.) Was Is Z Y

  6. SDO Thruster Locations Thruster plumes (for illustration only) shown at 45º half cone angle. ACS Thrusters 10° cant angle (22 N [5 lbf] class) Main Engine (450 N [100 lbf] class)

  7. Tank Configuration Changes Since SCR • SCR design was a dual-mode system with four propellant tanks • Design is now a bi-propellant (NTO/MMH) system • Two identical propellant tanks simplifies the system • Bi-propellant system allows ACS thrusters to back up the main engine SCR PDR GN&C Peer Review

  8. Propulsion Mechanical Configuration Fuel Tank Helium Pressurant Tanks High Pressure Control Module X Oxidizer Tank (Inside Cylinder And Frustum) Z Y Low Pressure Control Module Oxidizer Control Module Fuel Control Module Fill and Drain Valves

  9. Helium Helium R R R R HTK2 HTK1 SDO Propulsion Subsystem Fluid Schematic P-HTK FD-H1 P Normally closed 3-way if pyro-valve trade determines it is needed PV-H1 PV-H2 FD-H2 F-H LV-R2 LV-R1 FD-F1 FD-O1 R1 R2 FD-HF FD-HO P-FTK FD-H3 P-OTK P P P-REG P PV-VNT Fuel Tank (MMH) Oxidizer Tank (NTO) PV-F1 PV-O1 CV-F CV-O FD-F2 FD-O2 PV-BDN FD-CVF FD-CVO PV-F2 PV-O2 F-F F-O LV-FA LV-OA LV-FB LV-OB LV-FME1 LV-OME1 P-FTA P-OTB LV-FME2 LV-OME2 P P P P P-OTA P-FTB PV-FME PV-OME P P P-FME P-OME T-1A T-2A T-3A T-4A T-IB T-2B T-3B T-4B ME

  10. R R Key for Propulsion Schematic Pressure Transducer Fill and Drain Valve Pyrotechnic Valve (Normally Closed) Pyrotechnic Valve (Normally Open) Filter Latch Valve Regulator Check Valve Assembly P Propellant Management Device 22 N Thruster 490 N Thruster 1/4 Inch Line 3/8 Inch Line

  11. Propulsion Open Trades • Pyrotechnic valve trade initiated after GN&C PDR: • At PDR, NO 3-way pyrotechnic valve was identified as a single point failure • Helium tanks could not be vented after the NO 3-way valve was closed • A 3-way NC “bypass valve” may be added to the subsystem • Eliminates the NO 3-way single point failure • Allows helium tanks to be vented to fully comply with the orbital debris guidelines • Several bypass options were considered - best option is single NC 3-way (as shown in previous schematic) • Trade study is underway • Reliability group analyzed the baseline design vs. adding a vent valve • Adding the vent valve does not significantly increase the reliability of the system • Adding the vent valve is no longer a reliability decision, but hinges on how strictly we adhere to the orbital debris guidelines • Need to assess on-orbit risk of keeping pressurized helium tanks at EOL vs. the impacts of adding the vent valve

  12. Propulsion Analysis Status • Pressure Drop • Manifolds and component pressure drops modeled in AFT Fathom software • Worst case ME pressure drop ~ 18psid, ACS thruster pressure drop ~ 2psid • Water Hammer • System will be modeled in AFT Impulse and by Aerospace Corp. • Vapor Diffusion • Preliminary calculations performed by the Aerospace Corp., based on JPL method • Iron Nitrate Precipitation • Aerospace method will be used - too early to quantify because thruster vendor unknown • Thermal • Thermal branch is making model of tank thermal transients during maneuvers • All temperatures within required limits for thermal hot and cold cases • Plume • CC group performed analysis: no contamination issues • Filtration • Filter capacity analysis shows a factor of 3 margin under worst case conditions • Leakage • Leakage requirements compared to typical component capabilities • Internal and external leakage rates are not a problem • Propellant Budget (see following charts)

  13. Propellant Budget Description • Main engine nominal case (~ 10 % margin) • Main engine used to get to GEO • Nominal performance and no errors • Main engine worst case (~ 4 % margin) • Main engine used to get to GEO with 3 % performance shortfall (~ 9 sec Isp penalty) • Worst case errors include EELV dispersions, worst case knowledge, outage propellant • All errors added • Backup ACS thruster nominal case (~ 5 % margin) • ACS thrusters used to get to GEO (assumes main engine is never used) • Nominal ACS thruster performance and no errors • Backup ACS thruster worst case (~ 1.5 % margin) • ACS thrusters used to get to GEO with 3 % performance shortfall (~ 9 sec Isp penalty) • Worst case errors include EELV dispersions, worst case knowledge, outage propellant • All errors are RSSed because this case assumes main engine failure and poor thruster Isp • Knowledge uncertainty is being worked at this time • Needed for errors in mass flow rate, Isp, pressure transducers, temp. sensors, flow model • Needs more analysis • Propulsion Level 3 requirement is to have 3 % volume capacity margin • All cases meet this except ACS backup with worst case (a very conservative case) • Looking into ways to increase margin even more: • Refine analysis: tank capacity, residuals, outage propellant, knowledge uncertainty, etc. • Potential launch vehicle excess capacity for higher GTO perigee • (Least desirable) Larger tanks: increase diameter or change shape to increase volume

  14. Propellant Budget Details

  15. Component Vendor P/N Heritage Pressurant Tanks Lincoln Composites 2210136 HS-601 Fill & Drain Valves Vacco V1E10811, V1E10813 HS-601, HS-702, Spacebus 4000, Boeing (classified) Pressure Transducers Paine 213-36-450, 213-76-430 RHETT, NEAR, Pioneer, Voyager, Magellan Pyro Valves Conax Florida Corp. 1832-207, 1801-103, 1801-102, etc. HS-601, HS-702, LMSS A2100 Gas Filters Vacco F1D10286 HS-601, HS-702, Star-2, Spacebus 4000 High Pressure LV Vacco V1E10763 Muses-C, Astro-F, Boeing Defense Pressure Regulators Vacco 88355001 HS-601, HS-702, Boeing (classified) Check Valves Vacco V1D10826 SBIRS, Mars Odyssey, LM-Series 5000 Liquid Filters Vacco F1D10559 HS-601, HS-702 Low Pressure 3/8” LV Vacco V1E10875 HS-601, HS-702, Boeing (classified) Propellant Tanks PSI 80352 Mars Observer, Telstar, S7000 ACS Thrusters ARC N/A >1000 delivered, >750 flown Main Engine Aerojet R-4D-11 Extensive, dating back to Lunar Orbiter, also on several GOES and HS-601, HS-702 Propulsion Hardware Summary • NOTE: Components are place-holders only; no vendors have been selected yet.

  16. Build/Integrate Test Operation Propulsion I&T Flow Flow Components Thrusters Structure Tanks PGSE Water Hammer Test on Mockup Build Control Modules FD Module Main Engine  Bottom Deck Fuel/Ox Tanks  Bottom Deck EGSE HTK  Prop Structure CM and FDM Integrated Pressurant Lines Engine Manifolds Flow Balance Test Install ACS Thrusters Engine Manifold Proof Pressure Close-Out Welds Subsystem Proof Pressure External Leakage Tests S/C BUS Functional Tests Install Thermal Hardware Integrate Harness ACE-Prop End-To-End Tests Environmental Tests (Wet?) Post-Env. Pre-Ship Tests Ship to KSC Launch Site Tests Load Propellants Monitor & Launch

  17. HTK1 HTK2 Helium Helium FD1 P1 PV1 PV2 FD2 F1 LV2 LV1 FD6 FD7 R R R1 R2 FD3 R R P4 P2 P3 P5 FD5 FD4 CV1 PV3 CV2 Fuel Tank (MMH) Oxidizer Tank (NTO) PV6 PV7 PV4 PV5 FD8 FD9 F2 F3 LV8 LV7 LV3 LV5 LV6 LV4 P8 P6 LV10 LV9 P9 P7 PV8 PV9 P10 P11 T1A T2A T3A T4A T1B T2B T3B T4B ME OPS: Launch Site Operations, Propellant Loading, & Launch Configuration • Testing & Propellant loading at Astrotech • Helium tanks pyro-isolated at ~4000 psia • Pressurization system pyro-isolated at ~ 100 TBD psia • Propellant tanks pyro-isolated at ~ 100 TBD psia • Thruster manifold latch valves closed until just before launch • Thruster manifolds wet at 100 TBD psia ME manifold filled with gas at TBD psia

  18. R R P10 P11 OPS: Pressurization System Activation • ACS thrusters can be used at tipoff because their manifolds are wet • OPEN Helium tank pyro • Pressurization system goes to ~300 psia downstream of regulators HTK1 HTK2 Helium Helium FD1 P1 PV1 PV2 FD2 F1 LV2 LV1 FD6 FD7 R R1 R2 FD3 R P4 P2 P3 P5 FD5 FD4 CV1 PV3 CV2 Fuel Tank (MMH) Oxidizer Tank (NTO) PV6 PV7 PV4 PV5 FD8 FD9 F2 F3 LV8 LV7 LV3 LV5 LV6 LV4 P8 P6 LV10 LV9 P9 P7 PV8 PV9 T1A T2A T3A T4A T1B T2B T3B T4B ME

  19. R R P10 P11 OPS: Propellant Tank Pressurization • OPEN Main Engine latch valves while tanks are at 100 TBD psia • OPEN Oxidizer tank pyro • Open Fuel tank pyro • Fuel tank & manifolds are now pressurized to ~ 300 psia HTK1 HTK2 Helium Helium FD1 P1 PV1 PV2 FD2 F1 LV2 LV1 FD6 FD7 R R1 R2 FD3 R P4 P2 P3 P5 FD5 FD4 CV1 PV3 CV2 Fuel Tank (MMH) Oxidizer Tank (NTO) PV6 PV7 PV4 PV5 FD8 FD9 F2 F3 LV8 LV7 LV3 LV5 LV6 LV4 P8 P6 LV10 LV9 P9 P7 PV8 PV9 T1A T2A T3A T4A T1B T2B T3B T4B ME

  20. R R OPS: Orbit Raising Operations and ME, helium isolation • Pressure regulators maintain propellant tanks at ~300 psia • Dual check valves prevent propellant vapor mixing • Main Engine & ACS thrusters raise SDO to GEO • After GEO is achieved and after all deployments are performed, isolate main engine by closing pyro valves • Pressurization system is isolated, and propellant tanks are isolated from each other, via 3-way pyro HTK1 HTK2 Helium Helium FD1 P1 PV1 PV2 FD2 F1 LV2 LV1 FD6 FD7 R R1 R2 FD3 R P4 P2 P3 P5 FD5 FD4 CV1 PV3 CV2 Fuel Tank (MMH) Oxidizer Tank (NTO) PV6 PV7 PV4 PV5 FD8 FD9 F2 F3 LV8 LV7 LV3 LV5 LV6 LV4 P8 P6 LV10 LV9 P9 P7 PV8 PV9 P10 P11 T1A T2A T3A T4A T1B T2B T3B T4B ME

  21. R R P10 P11 OPS: On-Station Operations & Disposal • In GEO, the system operates in a shallow blowdown mode • ACS thrusters are used for stationkeeping and momentum management • Periodic (~6 month) thruster firings to flush Iron-nitrate buildup performed in concert with monthly momentum dumps • When disposal trigger is reached, ACS thrusters raise SDO to 300 km above GEO • Propellant tanks are vented through thrusters • (If added) NC pyro vent valve opened to vent helium from pressurization system HTK1 HTK2 Helium Helium FD1 P1 PV1 PV2 FD2 F1 LV2 LV1 FD6 FD7 R R1 R2 FD3 R P4 P2 P3 P5 FD5 FD4 CV1 PV3 CV2 Fuel Tank (MMH) Oxidizer Tank (NTO) PV6 PV7 PV4 PV5 FD8 FD9 F2 F3 LV8 LV7 LV3 LV5 LV6 LV4 P8 P6 LV10 LV9 P9 P7 PV8 PV9 T1A T2A T3A T4A T1B T2B T3B T4B ME

  22. Resources: Dry Mass Estimate • Allocation = 138 kg for dry mass • Current estimate ~ 132 kg • Margin is ~ 5 % (observatory-level margin is held at the systems level)

  23. Resources: Power Estimate • Allocation ~ 10 W for science mode • Current estimate ~ 10 W (transducers) • Configured power budget is being updated to reflect maneuver modes • Primary maneuver mode: ~ 300 W (worst case ME + 4 thrusters) • Backup maneuver mode: ~ 490 W (worst case 8 thrusters) • Heater power is allocated to thermal subsystem

  24. Propulsion Requirements & Documentation Status • Propulsion Level 3 requirements are configured (114 rqts.) Mechanical ICD 464-PROP-ICD-0007 Orbit Circularization Trade 464-PROP-TRD-0007 MRD Electronics Box Trade 464-PROP-TRD-0019 Electrical ICD 464-PROP-ICD-0008 Thermal ICD 464-PROP-ICD-0009 Performance Analysis 464-PROP-ANYS-0013 EGSE ICD 464-PROP-ICD-0054 Hydraulic Analysis 464-PROP-ANYS-0014 Requirements Doc. 464-PROP-REQ-0012 Filtration Analysis 464-PROP-ANYS-0015 Main Engine Spec. 464-PROP-SPEC-0018 Leakage Analysis 464-PROP-ANYS-0023 Main Engine SOW 464-PROP-LEGL-0020 SDOMIS Development Plan 464-PROP-PLAN-0032 ACS Thruster Spec. 464-PROP-SPEC-0068 Propellant Tank Spec. 464-PROP-SPEC-0017 Draft Propellant Tank SOW 464-PROP-LEGL-0019 ACS Thruster SOW 464-PROP-LEGL-0021 I&T Plan 464-PROP-PLAN-0033 In work

  25. SDO & Propulsion Subsystem Reviews / Meetings / Etc. to Date SDO Project Kickoff: Sep 02 SDO Systems Retreat: Mar 02 SDO MDR Mission Definition Retreat: Dec 02 SDO SRR System Requirements Retreat: Feb 03 SDO SCR System Concept Review: Apr 03 GN&C Peer Review: Jun 03 MMH redesign decision: Aug 03 SDO ICRR Initial Confirmation Readiness Review: Aug 03 Hypergol Training @ KSC: Aug 03 GPM/SDO Propulsion Requirements Meeting: Sep 03 SDO TIM#1 Technical Interchange Meeting @ KSC: Oct 03 GN&C PDR Preliminary Design Review: Dec 03 Propulsion Safety Tailoring Meeting @ KSC: Feb 03 SDO PDR Preliminary Design Review: Mar 04 SDO CDR Critical Design Review Feb 05

  26. Propulsion Major Open RFAs from GN&C PDR • 76 propulsion RFAs generated at the GN&C PDR • 44 are closed, 9 are almost closed, 23 are open • GSFC-13, GSFC-14 pressure analysis • NTO vapor now taken into account • Helium solubility into propellant - in work • Thermal transient effects - in work • GSFC-36, GSFC-39 PV3 SPF & EOL pyro/passivation • Trade study underway to see if we want to add a vent pyro valve • Eliminates SPF for PV-3 closing early • Provides helium venting to fully comply with orbital debris guidelines • JF-9, JF-22 propellant knowledge • Need to determine propellant knowledge error sources • Need to quantify propellant knowledge bounds • Affects disposal trigger • JF-29 wet vibration test • Mechanical may need to vibrate with wet tanks • Water is potentially harmful to the tanks, so it must be properly removed • JF-36, JF-38 tank procurement • Are we ready for tank procurement? Volume requirement must be known • Draft SOW and Specification are out for RFI • Volume margin is low for backup worst case • Looking into ways to increase propellant margin

  27. Propulsion Schedule Subsystem & Element CY 2003 CY 2004 CY 2005 CY 2006 CY 2007 CY 2008 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q2 Q3 Q4 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q1 4/8 8/03 5/04 2/05 3/04 LAUNCH MISSIONMILESTONES CR CDR ICR PDR PER PSR SRR/SCR Propulsion Milestones 12/10/03 8/23/05 CDR PDR Procurements Helium Tank Propellant Tanks Bi-Prop Main Engine Press Regs 1 = Spacecraft Integration 5 lb ACS Thrusters = Schedule Reserve Propellant Filters 2 = Instrument Integration Gas Filters 3 = Environmental Testing NO Pyro Valves 4 = Launch Site Operations NC Pyro Valves High Pressure Isolation Valves Low Pressure Isolation Valves High Pressure Fill & Drain Valves Low Pressure Fill & Drain Valves Fuel Check Valve Oxidizer Check Valve Weld Fittings High Pressure Transducers Low Pressure Transducers Suppression Orifices Flight Tubing Propulsion I&T Module I&T Propellant Tank Module I&T Install Rocket Engines &Test Module Spacecraft I&T 1 2 3 4 Launch

  28. Propulsion Risks & Issues to be Worked • Risks: • Risk 73: Aggressively pursuing methods to increase propellant margin • Risk 66: Bypass valve trade may eliminate the pyro SPF risk • Issues: • ACS thruster throughput • Some ACS thrusters do not meet throughput requirements for backup mode in steady-state operation • If those thrusters are procured, maneuver duty cycles must be adjusted to meet throughput requirements • Main Engine nozzle length • Main engine nozzle protrudes down into launch vehicle territory for 1 of the EELV options • Need to work with EELV vendor to see if this is a real issue or not • Need to verify no contact during separation from second stage

  29. Propulsion Conclusion • The propulsion Level-3 requirements are understood • Thoroughly reviewed and challenged by internal and external panels • Configured under SDOMIS as 464-PROP-REQ-0012 • The design meets all requirements • Only two yellow risk that are both being actively worked • Robust design with redundant hardware and backup thruster mode • We are ready to proceed with a detailed design • Propellant knowledge uncertainty details need to be worked • Complete Interface Control Documents • Initiate Long-Lead Procurements (tanks, engines, thrusters, pressure regulators) • Generate drawings and schematics • There is a lot of work to do, but the propulsion subsystem design was validated by a very rigorous GN&C PDR

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