SPICA / AIV&T issuesSpacecraft test program & model philosophy

Rev. C, Mar. 13th, 2010

by

H. Matsuhara, N. Takahashi, T. Nakagawa

Revised points (from Feb 19 ESA-JSAS telecon.) are indicated by red

ＳＰＩＣＡ Telescope Assembly (STA)

3m-class cooled telescope Monolithic Mirror

Ceramic material (SiC)

No deployable mechanism

Simple, Feasible, Reliable

Smooth PSF Essential for

Coronagraph

Herschel & AKARI Heritage AKARI: WFE 0.35μm, 6K (70cm) Herschel: WFE 6μm, 80K (3.5m)

SPICA: WFE 0.35μm, 5K (3.5m)

STA models & proposed delivery (tentative plan)

STM (Structure Thermal Model) Proposed delivery : Oct. 2012 (beginning of 3Q

of FY2012) AIT plan

Integrated as PLM (STM) Thermal test at cold (@Tsukuba 13m chamber) Integrated into Spacecraft (STM) Spacecraft Mechanical Environmental test & Thermal

Vacuum TestFM

Proposed delivery : Jan. 2017 (beginning of 4Q 2016)

STA Optical Performance test at cold (1)

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Date & duration ： 1Q of CY2017, 1-2 months

Place : 6m Space Chamber in Tsukuba Space

Center Configuration

IOB （ＦＭ dummy ）＋ STA(FM) Additional thermal sheild in the chamber

Purposes: Optical performance evaluation of ＳＴＡ at <10K Multiple measurements are connected by the

Stitching Method

STA Optical Performance test at cold (2)

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Anti-Vibration Table

Test Specimen Mount Table (with Shroud)

Pillar of V

acuum V

essel

Independent Foundation

Cryo Sorption Pumps

AC

F

Turbo Molecular Pumps

Gear

Motor

Interferometer

GHe

LN2

LN2 Shroud

GHe Shroud

AC

F

1

2

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5

67

8

STA Flat-mirror

5-axis stage

PLM Thermal Test at cold (STM and FM)

Purpose Evaluation of PLM cooling

system performances Alignment measurement

between STA and FPIA with FPC?

Date & Duration STM: April 2013 FM: Dec. 2017, ~2months

Method Additional shields in the

existing 13m space chamber in Tsukuba

Shields are externally lifted by mechanical coolers

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SPICA AIV&T timeline (tentative)

7Consistency need to be checked with Industries’ estimates !!

Key issues for FPI AIV&T

FPI’s system-level test plan should take account of the critical issues as below: (a) FPI is cooled to <5K with J-T coolers under

extremely careful Spacecraft thermal design. (b) disturbance and interference from J-T

coolers and AOCS (such as RW, gyro) To assure high-sensitivity (low-noise) in orbit

(c) Co-operation with FPC-G to establish the pointing stability

Interferences? Alignment? (d) Co-focus among FPIs (especially MIR’s)

Since STA 2ry cannot be adjusted so frequently in orbit

FPI Model philosophy

Cold FPIs Minimum number of Models required for the system level test (in

the previous page) is: FM (Flight Model) (& its spare) STM : structure thermal model CQM : cold qualification model

Warm Electronics Similar as above, except for the terminology (CQM PM

(proto-model) A concern about SAFARI Warm Electronics STM : can the

requested heat dissipation be simulated by a heater? Spacecraft DHS simulator(SpaceWire I/F) will be developed,

and distributed hopefully before 2014 ( under discussion)

STM (Structure Thermal Model) for FPIs

Purposes Evaluate their mechanical (at ambient temp.) & thermal

compliances at cold, in the system level (PLM or Spacecraft) Evaluate transfer function of mechanical disturbances

originated from FPIs Required Function

Same mechanical I/F specifications to FM Same thermal I/F specifications to FM Equipped with thermometers, acceleration sensors for

measurement of I/F environmental condition Simulate mechanical disturbance according to the system

operation modes Proposed Delivery

Oct. 2012 : before starting of assembly of PLM(STM) for the system Mechanical & Thermal Test

CQM (Cold Qualification Model) for FPIs

Purposes Evaluate thermal compliance at cold with J-T(PM) cooler Evaluate susceptibility to mechanical disturbances from J-T

(disturbance simulator) and AOCS simulator Evaluate electrical interferences among FPIs, J-T, AOCS

Required Function Same thermal, mechanical, electrical I/F specifications to FM Equipped with detectors operable at low-temperature, with the

same noise performance as that of FM Simulate heat-dissipation (load to J-Ts), mechanical disturbance

according to the system operation modes Equipped with a optical image, to check the co-focus among

FPIs Proposed Delivery

Apr. 2015 : when the PLM(FM) is available for us to test the items in page 2.

Earlier delivery enables us to feedback for the design of FM

FM (Flight Model) for FPIs

Purposes For on-orbit observations; for our scientific objectives, of

course! After delivery and assembly to FPIA, FM will go to the

“evaluation at cold” in the dedicated chamber for evaluation of interferences, co focus among FPIs

Required Function Science Grade optical, noise, and sensitivity performances! Note that after the test called “FPI evaluation at cold”, long-

wavelength channel detectors cannot be operated (even may not be switched on??) - so how to verify its health during the long waiting time before launch/cooling in orbit?

Delivery date of FM:

June 2016 (August 2016 at worst) in the proposed scenario.

FPI: ＳＰＩＣＡ system test plan

With STM: Mechanical Environmental test & thermal test at cold at the PLM

level Mechanical Environmental test & Thermal balance test at

Spacecraft level Measure disturbance at FPI from J-T cooler/AOCS

With CQM: Cooling compliance test with J-T (PM) most important Evaluate susceptibility to mechanical disturbances from J-T

(disturbance simulator) and AOCS simulator, Co-focus is also checked to some level at cold (tbd) Evaluate electrical interferences among FPIs, J-T, AOCS in the

1st whole FM V&T in 2016 if FM is not available yet With FM

FPI evaluation at cold (optical & electrical) STA optical performance test at cold Thermal test at cold at PLM level

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IOB

FPI FPI

LHe

Mech. Cooler (commercial)

FPI(CQM or FM) test config. in the 1st Whole FM V&T

1Q-2Q FY2016, checkout with FM Bus Module Electronics before assembly/integration of FM Bus System

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Focal Plane Instrument Assembly (FPIA) = IOB+FPI

TOB ： Telescope Optical Bench

IOB: Instrument Optical Bench

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2300 mm

FPI Evaluation at cold

Date & Duration: latter half of CY2016, 1-2 months

Place ： 6m Space Chamber at Tsukuba Space Centre (tbd)

Configuration: IOB(FM) ＋ FPI(FM) ＋ cooler(TBD – probably not

necessary) ＋ FPI warm electronics (FM) ( ＋ STA Simulator..)

Purposes: With all FM FPIs together, all functional, electrical &

optical performance evaluation at cold (operating temperature in orbit) as well as interference test.

Optical performance will be measures with a STA simulator.

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