TPF-C Technology Plan - Exoplanet Exploration Program - NASA

Chapter 7
7.5.8 Sub-scale EM Sunshield and Isothermal Enclosure
Scope
The testbed development begins during pre-Phase A, roughly at the beginning of FY06, and
concludes at the end of Phase A. Testbed design will be strongly affected by the need to
minimize thermal noise arising from the simulated space environment. Measurements will
evaluate the design of the sunshield, the thermal enclosures and the temperature control systems.
It is understood that there is a significant risk that the design verified by the testbed during
Phase A will change significantly by the time that the final flight design is set at the critical
design review. Early demonstration of thermal design feasibility in Phase A is judged a
worthwhile investment. Significant flight design changes may be incorporated and verified in a
updated testbed, if necessary, later in the program. The sub-scale EM sunshield and isothermal
enclosure have achieved TRL 3. Their schedule is given in Table 7-18.
Table 7-18. Sub-scale EM Sunshield and Isothermal Enclosure Schedule
Planned
Completion Date
Planned
Activities
Performance Targets
TRL
Pre-Phase A
Q4 FY05
Select baseline
sunshield
configuration
Characterize specularity of sunshield layers based on
scattering measurements of previously folded material
Select candidate
isothermal cavity
components
Survey available 10-100 micro-K thermometry components
(sensors and PID controllers) for room temperature control.
Consider the need for component space qualification
4-5
(comp)
Q2 FY06
Design the
sunshield
Complete thermal model of sunshield assembly including IR
BRDF, micrometeoroid effects, rip-stop features,
deployment system effects, etc.
2-3
(sys)
Design the
isothermal cavity
Requirements summary for the Isothermal Cavity testbed
completed and approved
Preliminary design including the dummy mirror and the
supporting AMS/PSS structure completed
Plan for preliminary qualification testing is established on
EMs sensors/controllers by early in Phase A if need is
identified
2-3
(sys)
Phase A
Complete design,
construction and
checkout of the
Sun/Iso testbed
with an installed
dummy mirror
system.
Complete
thermal
performance
testing of above
testbed.
By mid-Phase A, select a site for the testbed, update the
testbed requirements, complete a final design, and have it
reviewed and approved. Procure the components and
assemble the testbed late in Phase A. Perform any critical
component qualification testing per plan from pre-Phase A
In the presence of external thermal disturbances simulating
the effects of dithers and slews, demonstrate mirror
temperature control at the required flight levels.
Correlate analytical models to the test data to validate models
that can later be scaled to predict the PM thermal response of
the full-scale TPF-C to dithers and slews.
5-6
(comp)
5-6
(sys)
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