TPF-C Technology Plan - Exoplanet Exploration Program - NASA

Structural, Thermal, and Spacecraft Technology
Figure 4-13. Schematic of the Pointing Control Testbed.
Critical Testbed Components
(1) RWA disturbances on the S/C. The reaction wheels assembly (RWA) will induce vibrations
on the S/C. There is a separate structures testbed that will perform detailed evaluation of the
induced vibration and allow the creation of a vibration model. This model will then be used to
simulate the disturbances at the isolation interface. Additional disturbance models will include
the unloading of RWA.
(2) A model of the disturbances of the S/C transmitted to the telescope as a function of the
disturbance into the isolator. The testbed will require an isolator or isolator simulator with the
characteristics of the flight system (or an appropriate model of the performance) and a computer
controllable vibration inducing system, which can induce disturbance onto the testbed.
(3) A number of additional sources of disturbance are present on the telescope. These include
those caused by cryopumps, steering mirror actuation, secondary mirror actuation, and science
shutter actuations and disturbances transmitted through the cabling between the spacecraft and
payload.
(4) The acquisition camera will be part of the testbed. The acquisition camera is required to have
highly accurate measurements over up to a 60 arcsec FOV to provide for handoff and pointing to
the coronagraph. The acquisition camera design is not yet made final, but a simulated
acquisition camera will be included in the testbed.
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