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TPF-I SWG Report - Exoplanet Exploration Program - NASA

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C HAPTER 6<br />

Table 6-4. Requirements of the Formation Control Testbed vs. Flight Requirements<br />

Parameter Flight Performance Formation<br />

Control Testbed<br />

Comments<br />

Number of spacecraft 5 3<br />

Operational capability<br />

Standalone operations 5 yr 36 min Total floatation time<br />

Mission duration 5 yr 5+ yrs<br />

Observational duration ~20 hr ~15 min For an “observation on the fly”<br />

Availability Continuous 8 hrs/day Ground testbed facility<br />

Motion DOFs 6 5+1 FCT:+ articulated DOF<br />

Operating envelope 3D space 2D plane FCT: with limited out-of-plane<br />

Control 2 cm / 20 arcsec 5 cm / 60 arcmin<br />

Fault recovery Active and passive None<br />

Flight capability<br />

Sensor<br />

Inertial Gyro/accel Gyro/accel<br />

Celestial Star tracker Pseudo-star tracker<br />

Relative Coarse, Med., Fine Medium<br />

Actuator Thruster, RWA Thruster, RWA<br />

Control Architecture Distributed Distributed<br />

Control Algorithms Flight Flight Developed by FAST<br />

Dynamic DOFs 6 5 FCT: +1 articulated DOF<br />

Range of motion<br />

Angular-in-plane 2π 2π<br />

Angular-out-of-plane ± 45° ± 45°<br />

Linear-in-plane<br />

Linear-out-of-plane<br />

Maneuvers<br />

Limited by sensor<br />

range<br />

Limited by sensor<br />

range<br />

Limited by lab<br />

space<br />

Acquisition 3D space 2D space<br />

Array rotation in-plane Yes Yes<br />

Array re-sizing Yes Yes<br />

Array re-targeting Yes Yes<br />

Collision Avoidance 3D space 2D space<br />

± 25 cm Emulate deadband during<br />

observations<br />

142

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