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SPICA / AIV&T issues
Spacecraft 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


No deployable
mechanism


Herschel & AKARI Heritage
AKARI: WFE 0.35μm, 6K (70cm)
 Herschel: WFE 6μm, 80K (3.5m)
 SPICA: WFE 0.35μm, 5K (3.5m)


Ceramic material
(SiC)
Simple, Feasible,
Reliable
Smooth PSF

Essential for
Coronagraph
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 Test
FM

Proposed delivery : Jan. 2017 (beginning of 4Q
2016)
STA Optical Performance test
at cold (1)

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
4
STA Optical Performance test
at cold (2)
2
LN2 Shroud
GHe Shroud
Flat-mirror
STA
ACF
Cryo
Sorption
Pumps
5
Interfero
meter
6
ACF
8
1
7
Gear
Motor
Turbo
Molecular
Pumps
5-axis
stage
Test Specimen Mount Table (with Shroud)
4
Anti-Vibration Table
GHe
3
Pillar of Vacuum Vessel
LN2
Independent Foundation
5
PLM Thermal Test at cold
(STM and FM)

Purpose



Date & Duration



Evaluation of PLM cooling
system performances
Alignment measurement
between STA and FPIA with
FPC?
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
6
SPICA AIV&T timeline (tentative)
Consistency need to be checked with Industries’ estimates !!
7
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)


(c) Co-operation with FPC-G to establish the
pointing stability


To assure high-sensitivity (low-noise) in orbit
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 (protomodel)
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



Required Function





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
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




Required Function





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
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



Required Function



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
Science Grade optical, noise, and sensitivity performances!
Note that after the test called “FPI evaluation at cold”, longwavelength 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:




With CQM:





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
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
13
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
IOB
FPI
FPI
LHe
Mech. Cooler
(commercial)
14
Focal Plane Instrument
Assembly (FPIA) = IOB+FPI
2300 mm
TOB：Telescope
Optical Bench
IOB: Instrument
Optical Bench
15
FPI Evaluation at cold

Date & Duration:


Place：


6m Space Chamber at Tsukuba Space Centre (tbd)
Configuration:


latter half of CY2016, 1-2 months
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.
16