sdo preliminary design review: propulsion subsystem

Propulsion SDO Preliminary Design Review (PDR) – March 9-12, 2004

SDOSDOPreliminary Design Review:Preliminary Design Review:

Propulsion SubsystemPropulsion Subsystem

Gary Davis / Propulsion Subsystem LeadGary Davis / Propulsion Subsystem Lead

Propulsion Team Members:Propulsion Team Members:Jon Lewis / Flight Hardware Mark Mueller (Aerospace Corp.) / Analysis Jon Lewis / Flight Hardware Mark Mueller (Aerospace Corp.) / Analysis Support Support SPERT Review Team Apurva Varia / SPERT Review Team Apurva Varia / Analysis Analysis Mike Wilks / Technician Dewey Willis / Propulsion Mike Wilks / Technician Dewey Willis / Propulsion I&TI&T


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

Propulsion Functional Requirements (1/2)

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) ∆H and ∆V on orbit– ∆H using ACS thrusters in

on-pulsing mode– ∆V using ACS thrusters in

off-pulsing mode

Propulsion Functional Requirements (2/2)

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


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


• Removal of “forceless torque” and maneuver orientation requirements allowed for a simpler thruster configuration

Thruster Layout Changes Since SCR

Y

Z

Was

Was

Is

Is

Sketches only, not to scale! (Main Engine not shown.)


SDO Thruster Locations

Thruster plumes (for illustration only) shown at 45º half cone angle.

ACS Thrusters10° cant angle

(22 N [5 lbf] class)

Main Engine (450 N [100 lbf] class)


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

GN&CPeerReview

PDR


Propulsion Mechanical Configuration

Fill and Drain Valves

HeliumPressurant Tanks

Fuel Tank

Oxidizer Tank(Inside CylinderAnd Frustum)

Low PressureControl Module

OxidizerControl Module

FuelControl Module

High PressureControl Module

X

ZY


SDO Propulsion Subsystem Fluid Schematic

P P

Fuel Tank(MMH)

Oxidizer Tank(NTO)

PP

P

HeliumHTK1 HTK2

F-H

FD-H3

CV-F

PV-BDN

CV-OPV-F1

FD-F1 FD-O1

FD-F2 FD-O2F-OF-F

LV-FA LV-OA LV-FME1

LV-FME2

LV-OME1 LV-FB

LV-OME2

LV-OB

PV-FME PV-OME

ME

LV-R2LV-R1

R1 R2

FD-H2

FD-H1

FD-HF FD-HO

R

R R

R

P

PP

PP

T-1A T-2A T-3A T-4A T-IB T-2B T-3B T-4B

PV-VNT

PV-H1 PV-H2

PV-F2

PV-O1

PV-O2FD-CVF FD-CVO

Helium

P-HTK

P-REGP-OTKP-FTK

P-FTA

P-FTB

P-OTB

P-OTA

P-FME P-OME

Normally closed 3-way if pyro-valve trade determines it is needed


Key for Propulsion Schematic

P

R

R

Pressure Transducer

Fill and Drain Valve

Pyrotechnic Valve (Normally Closed)

Pyrotechnic Valve (Normally Open)

Filter

Latch Valve

Regulator

Check Valve Assembly

Propellant Management Device

22 N Thruster

490 N Thruster

1/4 Inch Line

3/8 Inch Line


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


Propulsion Analysis Status• Pressure Drop

– Manifolds and component pressure drops modeled in AFT Fathom software– Worst case ME pressure drop ~ 18 psid, ACS thruster pressure drop ~ 2 psid

• 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)


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


Propellant Budget DetailsMAIN ENGINE NOMINAL CASE MAIN ENGINE WORST CASE ACS THRUSTER NOMINAL CASE ACS THRUSTER WORST CASE

CATEGORY OXIDIZER FUEL TOTAL OXIDIZER FUEL TOTAL OXIDIZER FUEL TOTAL OXIDIZER FUEL TOTAL[kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg] [kg]

EELV dispersions 0 0 0.0 7.5 4.5 12.0 0.0 0.0 0.0 8.0 4.9 12.9A1 253.7 153.8 407.4 260 157.6 417.6 54.8 33.2 88 56.2 34.1 90.3A2 246.8 149.5 396.3 251.8 152.6 404.4 49.3 29.9 79.2 50.6 30.7 81.3A3 225.5 136.7 362.2 229 138.8 367.8 50.1 30.4 80.5 51.3 31.1 82.4A4 31 18.8 49.8 31.4 19 50.4 54.7 33.2 87.9 56.0 34.0 90.0A5 0.7 0.4 1.1 0.7 0.4 1.1 53 32.1 85.1 54.2 32.9 87.1A6 0.1 0.0 0.1 0.1 0 0.1 54.7 33.1 87.8 55.9 33.9 89.7A7 0.1 0.0 0.1 0.1 0 0.1 54.8 33.2 88 55.9 33.9 89.8A8 N/A N/A N/A N/A N/A N/A 53.7 32.6 86.3 54.8 33.2 88.0A9 N/A N/A N/A N/A N/A N/A 49.4 30 79.4 50.4 30.5 80.9A10 N/A N/A N/A N/A N/A N/A 49.8 30.2 80 50.7 30.7 81.4A11 N/A N/A N/A N/A N/A N/A 54.2 32.9 87.1 55.1 33.4 88.5A12 N/A N/A N/A N/A N/A N/A 49.2 29.8 79 50.0 30.3 80.3A13 N/A N/A N/A N/A N/A N/A 49.8 30.3 80.1 50.5 30.6 81.1A14 N/A N/A N/A N/A N/A N/A 53.5 32.4 85.9 54.2 32.9 87.1A15 N/A N/A N/A N/A N/A N/A 47.2 28.6 75.8 47.8 29.0 76.8A16 N/A N/A N/A N/A N/A N/A 12.1 7.3 19.4 12.2 7.4 19.6A17 N/A N/A N/A N/A N/A N/A 7.8 4.7 12.5 7.9 4.8 12.7A18 N/A N/A N/A N/A N/A N/A 0.7 0.4 1.1 0.7 0.4 1.1A19 N/A N/A N/A N/A N/A N/A 0.3 0.2 0.5 0.3 0.2 0.4A20 N/A N/A N/A N/A N/A N/A 0.1 0.1 0.2 0.1 0.1 0.2EWSK 0.8 0.5 1.3 0.8 0.5 1.3 1.1 0.6 1.6 1.0 0.6 1.6Momentum Unload 8.8 5.3 14.2 8.7 5.2 13.9 12 7.3 19.2 11.9 7.2 19.1Disposal 5.6 3.4 8.9 5.5 3.3 8.8 7.5 4.6 12.1 7.5 4.5 12.0MR outage propellant 0 0 0 17.5 18.9 36.4 0 0 0 18.1 19.6 37.7Knowledge Error 33.9 19.8 53.7 46.3 28.0 74.3 33.9 19.8 53.7 46.3 28.0 74.3Tank Residuals 9.5 5.7 15.2 9.5 5.7 15.2 9.5 5.7 15.2 9.5 5.7 15.2Manifold Residuals 0.6 0.3 0.9 0.6 0.3 0.9 0.6 0.3 0.9 0.6 0.3 0.9

NOTE: Errors RSS'edTOTAL [kg] 817 494 1311 870 535 1404 864 523 1387 896 547 1442

TANK CAPACITY 909 556 kg 909 556 kg 909 556 kg 909 556 kgMargin to capacity [kg] 91.9 61.8 kg 39.5 21.2 kg 45.2 33.1 kg 13.3 9.3 kgMargin to capacity [%] 10.1 11.1 % 4.3 3.8 % 5.0 6.0 % 1.5 1.7 %


Propulsion Hardware Summary

• NOTE: Components are place-holders only; no vendors have been selected yet.

Extensive, dating back to Lunar Orbiter, also on several GOES and HS-601, HS-702

R-4D-11AerojetMain Engine

>1000 delivered, >750 flownN/AARCACS Thrusters

HS-601, HS-702F1D10559VaccoLiquid Filters

HS-601, HS-702, Star-2, Spacebus 4000F1D10286VaccoGas Filters

SBIRS, Mars Odyssey, LM-Series 5000V1D10826VaccoCheck Valves

HS-601, HS-702, Boeing (classified)88355001VaccoPressure Regulators

HS-601, HS-702, LMSS A21001832-207, 1801-103, 1801-102, etc.

Conax Florida Corp.

Pyro Valves

RHETT, NEAR, Pioneer, Voyager, Magellan213-36-450, 213-76-430

PainePressure Transducers

HS-601, HS-702, Spacebus 4000, Boeing (classified)

V1E10811, V1E10813

VaccoFill & Drain Valves

Mars Observer, Telstar, S700080352PSIPropellant Tanks

HS-601, HS-702, Boeing (classified)V1E10875VaccoLow Pressure 3/8” LV

Muses-C, Astro-F, Boeing DefenseV1E10763VaccoHigh Pressure LV

HS-6012210136Lincoln Composites

Pressurant Tanks

HeritageP/NVendorComponent


Propulsion I&T Flow

Water Hammer Test on Mockup

Build Control Modules

FD Module Main Engine Bottom Deck

Fuel/Ox Tanks Bottom Deck

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

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

Flow Components TanksThrusters Structure

Test Build/Integrate Operation

PGSE

EGSE

S/C BUS


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

P1

RR

RR

P6P7P8P9

P11P10

Fuel Tank(MMH)

Oxidizer Tank(NTO)

Helium Helium

P5P4

FD2

FD1

HTK1 HTK2

PV1 PV2

F1

LV2LV1

R1 R2FD3

FD4

CV1 PV3 CV2PV6 PV7PV5PV4

FD5

FD6 FD7

FD8 FD9F3F2

LV3 LV4LV7

LV9

LV8LV5

LV10

LV6

PV8 PV9

ME

T1A T2A T3A T4A T1B T2B T3B T4B

P2 P3

ME manifoldfilled withgas at TBDpsia


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

P1

RR

RR

P6P7 P8P9

P11P10

Fuel Tank(MMH)

Oxidizer Tank(NTO)

Helium Helium

P5P4

FD2

FD1

HTK1 HTK2

PV1 PV2

F1

LV2LV1

R1 R2FD3

FD4


FD5

FD6 FD7

FD8 FD9F3F2

LV3 LV4LV7

LV9

LV8LV5

LV10

LV6

PV8 PV9

ME


P2 P3


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

P1

RR

RR

P6P7 P8P9

P11P10

Fuel Tank(MMH)

Oxidizer Tank(NTO)

Helium Helium

P5P4

FD2

FD1

HTK1 HTK2

PV1 PV2

F1

LV2LV1

R1 R2FD3

FD4


FD5

FD6 FD7

FD8 FD9F3F2

LV3 LV4LV7

LV9

LV8LV5

LV10

LV6

PV8 PV9

ME


P2 P3


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

P1

RR

RR

P6P7 P8P9

P11P10

Fuel Tank(MMH)

Oxidizer Tank(NTO)

Helium Helium

P5P4

FD2

FD1

HTK1 HTK2

PV1 PV2

F1

LV2LV1

R1 R2FD3

FD4


FD5

FD6 FD7

FD8 FD9F3F2

LV3 LV4LV7

LV9

LV8LV5

LV10

LV6

PV8 PV9

ME


P2 P3


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

P1

RR

RR

P6P7 P8P9

P11P10

Fuel Tank(MMH)

Oxidizer Tank(NTO)

Helium Helium

P5P4

FD2

FD1

HTK1 HTK2

PV1 PV2

F1

LV2LV1

R1 R2FD3

FD4


FD5

FD6 FD7

FD8 FD9F3F2

LV3 LV4LV7

LV9

LV8LV5

LV10

LV6

PV8 PV9

ME


P2 P3


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)

Component Allocation Estimate Mass (kg) # Mass/Unit Status Notes[kg] [kg] [kg] [#] [kg/unit]

[TOTAL dry mass] 138.00 131.55 1.05NTO Oxidizer tank 18.4 1 18.40 ETU PSI 80352-1

MMH fuel tank 18.4 1 18.40 ETU PSI 80352-1Helium tanks 21.32 2 10.66 ETU Slightly bigger PSI He tank 80446-1

Main engine [100 lbf] 5.2 1 5.20 ETU Aerojet R-4DACS thrusters [5 lbf] 7.2 8 0.90 ETU ARC 5 lbf

Pressure Transducers 2.69 10 0.27 ETU PaineHP Latch Valves 0.682 2 0.34 ETU Vacco V1E10763-01LP Latch Valves 5.984 8 0.75 ETU Vacco V1D10392-01

Fill and Drain 2.64 11 0.24 ETU Vacco V1E10813-01 (added 2 per RFAs)Gas System Filters 0.114 1 0.11 Est Vacco F1D10286-01 (reduced to 1 per simplification)Propellant Filters 0.6 2 0.30 ETU Vacco F1D10559-01

Check Valves 0.544 4 0.14 ETU Vacco V1D10495-01Pressure Regulators 3.4 2 1.70 ETU Vacco 64720-1

Plumbing Lines 7.056 80 0.09 Est ESTIMATE [Using 0.0882 kg/m titanium tubing 3/8X0.028]Thermal Hardware 32 80 0.40 Est ESTIMATE [Using MAP thermal tubing mass of 0.4 kg/m]

NC pyro valves 0.66 6 0.11 ETU CONAX 1832-207NO pyro valve (ME) 0.322 2 0.16 ETU CONAX 1801-102

NO pyro valve (3-way) 0.394 2 0.20 ETU CONAX 1801-103 (added another in mass budget in case we vent)Fasteners 3.948 210 0.02 Est 18.8 g for bolt+nut+2 washers. No tank fasteners.

0Dry mass margin 4.67 %


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

Current Nominal Mode Orbit Injection Mode (Primary) Orbit Injection Mode (Backup)Components Allocation # W/unit Power (W) # W/unit Power (W) # W/unit Power (W)

[W] [#] [W/unit] [W] [#] [W/unit] [W] [#] [W/unit] [W]TOTAL 10.0 10.0 300.0 490.0Pressure Tranducer 10 1.0 10.0 10 1.0 10.0 10 1.0 10.0490 N REM Driver 0 50.0 0.0 1 50.0 50.0 0 50.0 0.022 N REM Drivers 0 60.0 0.0 4 60.0 240.0 8 60.0 480.0Iso-valve Driver 0 30.0 0.0 0 30.0 0.0 0 30.0 0.0Pyro Circuits N/A N/A N/A


Propulsion Requirements & Documentation Status

MRD

Requirements Doc. 464-PROP-REQ-0012

Orbit Circularization Trade464-PROP-TRD-0007

SDOMIS

Mechanical ICD464-PROP-ICD-0007

Electrical ICD464-PROP-ICD-0008

Thermal ICD464-PROP-ICD-0009

EGSE ICD464-PROP-ICD-0054

Performance Analysis464-PROP-ANYS-0013

Hydraulic Analysis464-PROP-ANYS-0014

Filtration Analysis464-PROP-ANYS-0015

Leakage Analysis464-PROP-ANYS-0023

ACS Thruster SOW464-PROP-LEGL-0021

ACS Thruster Spec.464-PROP-SPEC-0068

Main Engine SOW464-PROP-LEGL-0020

Main Engine Spec.464-PROP-SPEC-0018

Propellant Tank SOW464-PROP-LEGL-0019

Propellant Tank Spec.464-PROP-SPEC-0017

I&T Plan464-PROP-PLAN-0033

Development Plan464-PROP-PLAN-0032

Draft

In work

Electronics Box Trade464-PROP-TRD-0019

• Propulsion Level 3 requirements are configured (114 rqts.)


SDO & Propulsion Subsystem Reviews / Meetings / Etc. to Date

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


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


Propulsion Schedule

Q4

CY 2003 CY 2004 CY 2005 CY 2006 CY 2007Q1 Q2 Q3 Q4

Q1 Q2 Q3 Q4

Q1 Q2 Q3 Q4

Q1 Q2 Q3 Q4

Q1 Q2 Q3 Q4

Q1 Q2 Q3 Q4

CY 2008

MISSION MILESTONES

Propulsion Milestones

Propulsion I&T

Subsystem & Element

PDR12/10/03

CDR8/23/05

Procurements

Module I&T

Install Rocket Engines &Test Module

1 = Spacecraft Integration= Schedule Reserve

2 = Instrument Integration3 = Environmental Testing4 = Launch Site Operations

Spacecraft I&T

Helium Tank

5 lb ACS ThrustersPropellant Filters

High Pressure Isolation Valves

High Pressure Transducers

Suppression Orifices

Propellant Tank Module I&T

ICRSRR/SCR PDR

5/04

CR CDR

2/05

PSR

8/03LAUNCH

PER

3/044/8

Launch1 2 3 4

Propellant TanksBi-Prop Main Engine

Press Regs

Gas FiltersNO Pyro ValvesNC Pyro Valves

Low Pressure Isolation ValvesHigh Pressure Fill & Drain ValvesLow Pressure Fill & Drain ValvesFuel Check ValveOxidizer Check ValveWeld Fittings

Low Pressure Transducers

Flight Tubing


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

Con

Like

Crit

Active Risks73 4 3 Propellant Budget

Risks Accepted with Process Controls64 5 2 Propulsion System Pyro Valve PV3

Risk ID Risk Title

Feb. '04


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