INSPECT Sensor Suite for On-Orbit Inspection and Characterization with Extravehicular Activity Spacecraft

Most inspection and maintenance operations at the International Space Station (ISS) rely on astronaut extravehicular activities (EVAs). Autonomous or radio-controlled spacecraft that work in conjunction with astronauts could improve diagnostic and imaging capability during EVA missions. The Integrated Navigation Sensor Platform for EVA Control and Testing (INSPECT) system is a proposed testbed for EVA systems that builds off of the Synchronized Position Hold Engage Reorient Satellites (SPHERES) facility at MIT and the International Space Station (ISS). INSPECT’s imaging payload includes a stereo-vision optical camera, an optical range finder (ORF) and a thermal infrared (IR) imager. A configuration of four miniature control moment gyroscopes (CMGs) acquired from Honeybee Robotics work alongside SPHERES CO2 thrusters to provide enhanced pointing precision and slew control for the imaging payload. Results from laboratory testing and microgravity experimentation aboard a NASA reduced gravity aircraft have validated sensor fusion algorithms and have demonstrated the torque capability of INSPECT CMGs. Torques of 120mN-m have been demonstrated with the CMGs, as compared to individual thruster pairs capable of providing torques of 20mN-m from 0.1N thrust for each thruster at a moment arm of 10 cm. Offsets of the center of mass from the system’s geometric center were computed to be: 4.4cm in x, -1.5cm in y, and 4.6cm in z. Additionally, the moment of inertia about the zaxis was computed to be -0.398 kg-m.