Research Containing: Trajectory
This paper presents the results for the first ever flight demonstration of the Zero Propellant Maneuver (ZPM) TM attitude control concept. On November 5, 2006, the ZPMTM was used to reorient the International Space Station by 90 degrees without using any propellant. By maneuvering along a pre-planned trajectory which was optimized to take advantage of naturally occurring environmental torques, the Space Station CMGs were maintained within operational limits. The trajectory was obtained from a PseudoSpectral solution to a new optima attitude control problem. With the flight test, the breakthrough capability to simultaneously perform large angle attitude maneuver and momentum desaturation without the need to use thruster was established. The flight implementation did not require any modification to flight software. The approach is applicable to any spacecraft that are controlled by momentum storage devices.
Since 2006 the SPHERES facility aboard the International Space Station has enabled research of high-risk autonomy algorithms which would not otherwise be conducted in a regular space mission. A thread of research with several demonstrations aboard the ISS is Collision Avoidance. Through two SPHERES test sessions over the course of a year, researchers have developed an efficient autonomous collision avoidance controller, deployed it on a representative microprocessor, and demonstrated its effectiveness as a reliable low-level safetey routine.
Implementation of Satellite Formation Flight Algorithms Using SPHERES aboard the International Space Station
The MIT’s Space Systems Laboratory developed the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) as a risk-tolerant spapceborne facility to develop and mature control, estimation, and autonomy algorithms for distributed satellite systems for applications such as satellite formation flight. Tests performed study interferometric mission-type formation flight maneuvers in deep space. These tests consist of having the satellites trace a coordinated trajectory under tight control that would allow simulated apertures to constructively interfere observed light and measure the resulting increase in angular resolution. This paper focuses on formation initialization (establishment of a formation using limited field of view relative sensors), formation coordination (synchronization of the different satellite’s motion) and fuel-balancing among the different satellites.