I n t e g r a t e d D e s i g n C e n t e r / M I s s I o n D e s I g n L a b o r a t o r y N A S A G O D D A R D S P A C E F L I G H T C E N T E R Do

I n t e g r a t e d D e s i g n C e n t e r / M I s s I o n D e s I g n L a b o r a t o r y

N A S A G O D D A R D S P A C E F L I G H T C E N T E R

Do not distribute this information without permissionfrom Gerry Daelemans ([email protected])

X-ray Missions Delta:AXSIO Redux

ThermalKimberly Brown

30 April – 1 May, 2012

Thermal, p2Final Version

M i s s i o n D e s i g n L a b o r a t o r y

30 April – 1 May, 2012X-ray Delta: AXSIO Redux


Thermal Control Subsystem Summary for S/C Bus

• Passive S/C radiators for spacecraft components– Thermal coating applied to exterior of closeout panels on anti-sun side– Heat pipes embedded in radiator panels

• Cho-therm interface material used for box to panel interface (electrically and thermally conductive) except for battery (Nusil interface)

• Heat pipes transfer heat from boxes (not mounted to radiators) to radiator panels

• Active heater control via mechanical thermostats (operational and survival)– Primary and redundant heat circuits– Two thermostats in series per circuit– Kapton film heaters attached to components, including propellant tanks– Line heaters on propellant lines and fill-and-drain valves

• Internal surface coatings has high emittance (Aeroglaze Z307 black paint) • Except for radiators, exterior of S/C bus and metering structure is insulated

with MLI blankets (15 layers make-up) • S/C bus is thermally isolated from FMA (24 mounting points)• Back side of portion of solar array that serves as sunshield is insulated with

MLI• Flight thermistors for telemetry of temperatures





Thermal Control Subsystem Summary for Instruments

• FMA is cold biased and has active heater control via heater controllers– Primary and redundant heat circuits– Same heater circuits for operational and survival (10ºC lower set point for survival)

• FMA is thermally isolated from S/C bus• Passive radiators for XMS and XGS components

– Radiators shaded from sun– Heat pipes isothermalize radiator panels, except for XGS CCD radiator

• Heat pipes transfer heat from components to radiator panels, except for XGS CCDs

• Active heater control via mechanical thermostats (survival mode)– Primary and redundant heat circuits– Two thermostats in series per circuit– Kapton film heaters attached to components

• Heat pipes and backside of radiators are insulated with MLI blankets (15 layers make-up)

• Flight thermistors for telemetry of temperatures





S/C Bus Thermal Control Subsystem Functional Block Diagram

Battery (Li-Ion)

Thermostatically controlled heaters

Avionics

Comm System

MLI Radiators

RW RW RW

RWE RWE RWE

Gyro

Thrusters

PSE

Radiators Reject Waste Heat to Space

FMA

Propellant Tanks, Lines and Fill-and-Drain Valves

RW

RWE





Orbit Thermal and Charged Particle Environment

•L2 provides excellent thermal environment for passive (radiative) cooling – Earthshine and moonshine negligible

•Thermal disturbances– Sun angle changes due to ±10º roll and ±45º pitch – Seasonal variation of solar flux

•Charged particles environment requires electrically conductive thermal coatings– Radiators (anti-sun side) have NS43G yellow paint which has a high

emittance (0.9)• Flown on WIND, POLAR, MAP, etc.

– MLI outer covers have silver conductive composite coating (ITO/SiOx/Al2O3/Ag) which has a low absorptance (0.08 at BOL) and high emittance (0.6)• Flown on WIND, IMAGE, etc.





Instrument Radiator Sizing

Cryocooler (Compressor & Control Electronics) Electronics Boxes

XMSCryocooler Radiator

E-Box Radiator

Ammonia Heat Pipe (Redundancy Not Shown)





Instrument Radiator Sizing

XGS Power (W) IXO AXSIO Option A*

AXSIO Option B*

Scaled From

XGS Total 114 52 40 # of signal chains:IXO: 128; AXSIO-A: 64 (total);AXSIO-B: 40

*Option A: 2 pair of 30-deg gratings sectors, 2 x 8-CCD cameras Option B: 1 pair of 45-deg grating sectors, 1 x 10-CCD camera

Radiator Cools CCDs to -90°C Passively

CCD Power Dissipation: 0.1 W each (1.6 W Total)DEA & DPA Power Dissipation: 50 W (-40°C to 50°C operating; -55°C to 60°C survival)

CCDs are cold biased and trim heaters maintain temperature stable

Ethane heat pipes isothermalize CCDs

Ammonia Heat Pipe Transport Heat from DEA & DPA to Remote Radiator

Instrument shown will be scaled down from 32 to 16 CCDs





XGS CCD Parasitic Heat Load

Number of Conductors per Ribbon

40

Number of Ribbons 16

Conductor Material Stainless Steel 316

Conductor Size 28 AWG

Conductor Diameter 0.32004 mm

Conductor Length 0.5 m

Thermal Conductivity of Conductor

16 Wm-1K-1 at -50ºC

DEA temperature 20ºC

FPA Temperature -120ºC

Heat transfer by DEA harness to FPA

0.230 W

Number of heater circuits (primary and redundant)

2

Number of conductors 4

Conductor Material Copper




Thermal Conductivity of Conductor

400 Wm-1K-1 at -50ºC

DPA temperature 20ºC


Heat transfer by heater harness to FPA

0.150 W

Number of heater controller temperature sensors (primary and redundant) 2

Number of flight temperature telemetry sensors for FPA, paddle and radiator (instrument and S/C)

12

Number of conductors 28

Conductor Material Phosphor-Bronze




Thermal Conductivity of Conductor 65 Wm-1K-1

DPA temperature 20ºC


Heat transfer by temperature sensor harness to FPA 0.020 W

CCD Radiator Heat Rejection: 1.6 W + 0.4 W = 2 W

(2.6 W after adding 30% contingency)





Instrument Power Dissipation Summary

Power Dissipation (W) Power Dissipation (W)With 30% Contingency

XMS Electronics Boxes 751 976

XGS DEA & DPA 50 65

XMS Cryocooler 350 455

One radiator for cryocooler (compressor and control electronics) and one radiator for XMS electronics boxes and XGS DEA and DPA





Radiator and Heat Pipe Orientation

•Cryocooler compressor motor mount and control electronics located slightly below radiator– Allows cryocooler CCHP operate in reflux mode to overcome

gravity problem in ground testing

•CCHPs transfer heat from electronics boxes to radiator– CCHP attached to exterior of components (IceSat GLAS

heritage)– Multiple CCHPs provides sufficient heat transport capacity

and redundancy• 2.8575 cm diameter ammonia pipe; 1372 W-m limit• 1.27 cm diameter: 152 W-m limit

– Radiators slightly above CCHP evaporators to allow CCHP operate in reflux mode in ground testing





Instrument Survival Heater Circuits

• Survival heaters and thermostats attached to exterior of electronics boxes and cryocooler motor mount– Set point of primary heater circuit thermostats is 3ºC larger than redundant

heater circuit– Powered by S/C bus directly

Control Primary Circuits

Redundant Circuits

XMS Electronics Boxes

Mechanical Thermostats

16 16

XMS Cryocooler (Compressor and

Control Electronics)

Mechanical Thermostats

2 2

XGS DEA & DPA Mechanical Thermostats

2 2

XGS CCD Mechanical Thermostats

1 1

Total 22 22





FMA Thermal Requirement

•Mirror segment temperature gradient requirement depends on gradient topology

•Rule of thumb is 20°C±0.5°C• Recent IXO STOP analysis has a ± 0.1°C goal





FMA Thermal Design

• FMA is cold biased• Active heater control maintain mirror segment

temperature stable and meets thermal gradient requirement

• Heater locations– Conductive portion of thermal pre-collimator– Exterior of module walls– Fore section of metering structure

• Non-conductive portion of thermal pre-collimator minimizes heater power

• Sunshield prevents direct solar impingement on FMA• FMA thermally isolated from S/C bus





FMA Heater Locations

Conductive Portion of Pre-collimator

Non-Conductive Portion of Pre-collimator

Fore Portion of Metering Structure Exterior





S/C Bus Power Dissipation

Nominal Average

(W)

Nominal Average with

30% Contingency

(W)

PSE 114 148

C&DH 147 191

ACS 62 81

Propulsion* 5 6.5

Data Systems 44 57

Total 372 484**

Safehold (W)

Safehold with 30%

Contingency (W)

PSE 83 108

C&DH 29 38

ACS 60 78

Propulsion 5 6.5

Data Systems 44 57

Total 221 287

Launch (W)

Launch with 30% Contingen

cy (W)

PSE 43 56

C&DH 29 38

ACS 23 35

Propulsion 5 6.5

Data Systems 0 0

Total 104 135

*Pressure Transducer**Used for radiator sizing





S/C Bus Thermal Control

MLI on Exterior of Metering Structure

MLI on Exterior of S/C Bus with Exception of Radiators

MLI on Backside of Sunshield Portion of Solar Array

Sunshield MLI





S/C Bus Thermal Control

MLI on interior to radiatively isolate from FMA

CCHP isothermalizes mounting interfaces for FMA (redundancy not shown)

CCHP embedded in honeycomb radiator panel





S/C Bus Propulsion Subsystem Thermal Control

Heaters, thermostats and MLI to maintain temperature of propellant tanks, lines and valves above 10ºC. Heater circuits have redundancy.

Propellant tanks, lines and valves are thermally isolated from S/C bus structure

Cat-bed heaters commanded to heat reactors on prior to firing

Aluminum tape spreads heat along propellant lines

0.559 m Diam.





Thermal Model

S/C Bus

Metering Structure

Instrument Radiators

S/C Bus Radiators

Solar Array XGS CCD Radiator

XMS Cryocooler Radiator





Thermal Model

Mirror Module Pre-collimator

Stray Light Baffle

Conductive Portion of Pre-collimator (Heater Controlled)





Summary of Radiator Sizes

Components Radiator Area (m2) CoatingXMS Cryocooler Radiator 1.46 NS43G

XMS Electronics Boxes and XGS DEA/DPA Radiator

3.1 NS43G

XGS CCD Radiator 0.07 NS43G

S/C Bus Radiator 1.45 NS43G





Summary of Instrument Survival Heater Power

Peak Heater Power (W)

Orbital Average Heater Power (W)

XMS Electronics Boxes 790 553

XMS Cryocooler (Compressor and

Control Electronics)

131 92

XGS DEA & DPA 37 26

XGS CCD 1.4 1

Total 960 672





Summary of S/C Bus Survival Heater Power

Peak Heater Power (W)

Orbital Average Heater Power (W)

Total 142 100





Mass Estimates/TRL

S/C ComponentsMass

Each (kg) Qty

Mass Total (kg) TRL

MLI (15-layers) for Metering Structure (71 m2) 42.6 1 42.6 9

MLI (15-layers) for S/C Bus (17.7 m2) 10.62 1 10.62 9Heat Pipes (CCHP) Embedded in S/C Closeout Panels (1.2 m long; 1.27 cm diam.) 0.36 16 5.76 7Heat Pipes (CCHPs) for Transpoting Heat from Electronics Boxes to Radiators (1.5 m long; 2.8575 cm diam.) 0.586 4 2.344 7Heat Pipes (CCHPs) for Isothermalizing FMA Mounting Interfaces (6 m long; 2.8575 cm diam.) 2.344 2 4.688 7

S/C Bus Radiator Radiator Paint (NS43G silicate; 1.45 m2) 0.193 1 0.193 7

Heaters on Propellant Tanks (redundancy included) 0.006 96 0.576 9

Heaters on Propellant Lines (redundancy included) 0.002 24 0.048 9

Thermostats on Propellant Tanks (redundancy included) 0.006 48 0.288 9

Thermostats on Propellant Lines (redundancy included) 0.006 48 0.288 9Thermostats for Survival Heaters -- Honeywell 3100 Series (redundancy included; 8 per box) 0.006 80 0.48 9Survival Heaters (redundancy included; 8 per electronics box or cryocooler) -- Kapton Film 5.5 cm x 6.4 cm 0.002 96 0.192 9

MLI (15-layers) for Propellant Tanks and Lines (1.1 m2) 0.66 1 0.66 9

MLI on Solar Array Backside (2.4 m sunshield) (7.2 m2; 15-layer) 4.32 1 4.32 9

S/C Bus Thermistors for Telemetry 0.001 40 0.04 9





Mass Estimates/TRL

S/C ComponentsMass

Each (kg) Qty

Mass Total (kg) TRL

XMS Cryocooler Radiator (1.46 m2; 0.254 cm aluminum) 10.012 1 10.012 7

XMS Cryocooler Radiator Paint (1.46 m2; NS43G silicate) 0.194 1 0.194 9

XMS and XGS Electronics Radiator (3.1 m2; 0.254 cm aluminum) 21.263 1 21.263 7

XMS and XGS Electronics Radiator Paint (3.78 m2; NS43G silicate) 0.503 1 0.503 9

XGS CCD Radiator (0.07 m2; 0.254 cm thick; aluminum) 0.48 1 0.48 7

XGS CCD Radiator Paint (0.07 m2; NS43G silicate) 0.009 1 0.009 9Heat Pipes (CCHP) on XMS Electronics (2 m long; 2.8575 cm diam.; aluminum; ammonia) 1 2 2 7Heat Pipes (CCHP) on XGS Electronics (0.8 m long; 2.8575 cm diam.; aluminum; ammonia) 0.4 2 0.8 7Spreader Heat Pipes (CCHP) on XMS & XGS Electronics Box Radiator (1.3 m long; 1.27 cm diam.) 0.39 8 3.12 7Spreader Heat Pipes (CCHP) on XMS Cryocooler Radiator (1 m long; 1.27 cm diam.) 0.3 8 2.4 7

MLI (15-layers) on Cryocooler Radiator Backside (1.46 m2) 0.876 1 0.876 9

MLI (15-layers) on XMS & XGS Electronics Radiator Backside (3.1 m2) 1.88 1 1.88 9

MLI (15-layers) on XGS CCD Radiator Backside (0.07 m2) 0.04 1 0.04 9

MLI (15-layers) Tent for XMS Electronics (5 m2) 3 1 3 9

MLI (15-layers) Tent for XGS Electronics (0.8 m2) 0.48 1 0.48 9

XMS & XGS Sunshield MLI (6 m2; 15-layer with Dunmore fabric) 3.6 1 3.6 7

Buttons, Velcro and Tape for MLI 5.000 1 5 9





Mass Estimates/TRL

S/C Components

Mass Each (kg) Qty

Mass Total (kg) TRL

Thermostats for XMS & XGS Electronics Survival Heaters -- Honeywell 3100 Series (redundancy included; 8 per box) 0.006 96 0.576 9Survival Heaters (redundancy included; 8 per electronics box or cryocooler) -- Kapton Film 5.5 cm x 6.4 cm 0.002 96 0.192 9

XMS & XGS Thermistors/Platinum RTDs for Telemetry and Heater Control 0.001 40 0.04 9

Total 129.56

2





Conclusions and Recommendations

• S/C bus, XMS and XGS thermal design meets temperature requirements and have sufficient margin

• Instrument radiators must be above CCHP evaporators to make CCHP testable (in reflux mode) during ground testing

• STOP analysis is needed to evaluate if FMA thermal design meets thermal-structural distortion requirement

• Evaluate thermal effect of solar array as sunshield on FMA mirror temperature gradient– If necessary, consider optical solar reflector/ITO (no solar cells) on

“sunshield” portion of solar array





Delta Charts for AXSIO Redux

• Change in the MEL are the following: Removed mass for

– XMS Cryocooler Radiator, Paint, MLI on backside of Radiator– XMS Spreader heat pipes for XMS Cryocooler Raditor– XMS Electronics Radiator, Paint, MLI on backside of Radiator– XMS Electronics MLI Tent– Buttons, Velcro and Tape for MLI (included in MLI weights)





AXSIO Redux MEL

• AXSIO Redux New MEL includes:– Metering Structure MLI, thermistors– S/C MLI, paints, heaters, thermostats, thermistors– Heat Pipes embedded in S/C closeout panels– Heat Pipes for transporting heat from electronic boxes to radiators– Heat Pipes for isothermalizing FMA mounting interfaces – XGS Electronics MLI tent, heaters, thermistors, thermostats, Radiator, Radiator

Paint, MLI on backside of Radiator.– XGS CCD Radiator, Radiator Paint, MLI on backside of Radiator.

Sized a Radiator for XGS based on 50 Watts 0.182 m2 to add in MELRemoved 12 heaters for tanks and lines from MEL (estimate) of how many per tank





S/C Bus Thermal Control Subsystem Functional Block Diagram

Battery (Li-Ion)

Thermostatically controlled heaters

Avionics

Comm System

MLI Radiators

RW RW RW

RWE RWE RWE

Gyro

Thrusters

PSE

Radiators Reject Waste Heat to Space

FMA

Propellant Tanks, Lines and Fill-and-Drain Valves

RW

RWE

Documents

I n t e g r a t e d D e s i g n C e n t e r / M I s s I o n D e s I g n L a b o r a t o r y N A S A G O D D A R D S P A C E F L I G H T C E N T E R Do