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Many organizations have adopted agile values and principles in their products and services to provide increasing value to their customers. Although agile started with software development, it has been applicable and used in different industries and disciplines, including the space industry. This article presents the practical implications of teams transitioning to be agile teams using a general inductive analysis of 33 individuals from different NASA agile teams. The findings and recommendations are part of a larger effort performed as part of the development of a model for agile leadership. Some organizations may see agile as very risky and costly, and this article provides some guidance derived from the data to help support planning for agile transformation efforts. • Agile transformations of NASA Agile teams. • Being Agile with a continuous learning mindset. • Ability to create sustainable value to the customer in a technology-driven organization. • Recommendations to becoming Agile organizations. [ABSTRACT FROM AUTHOR]

To overcome the singularity problem of control moment gyros (CMGs) and simultaneously provide a lightweight, agile, and simple dynamical system, a CMG system called a double-gimbal scissored-pair control moment gyro (DGSPCMG) was recently proposed. The DGSPCMG is a hybrid mechanism that combines scissored-pair CMGs and a double-gimbal mechanism; further, the outer singularities in this system (saturation singularities) can be escaped by steering the scissored-pair gimbals. This system generates less perturbation torque and has almost no inner singularities except at the origin and the line along the outer gimbal axis. This paper proposes model predictive control (MPC) based steering laws for the mentioned CMG system. The proposed MPC based steering laws can directly provide the optimal gimbal rate under the nonlinear constraints in real time without using the inverse of the CMG Jacobian matrix, and hence, the singularities do not have to be considered when determining the gimbal steering rate of this system. Three objective functions are considered in the steering law design: fast maneuver-weighted type, minimum control energy type, and a hybrid of these two types. The control performances of these three MPC-based steering laws are compared via numerical simulations. Results demonstrate that the hybrid type can achieve both a short rise time of the angular velocity at the initial stage of control, and smooth stabilization to the target attitude; moreover, its settling time and control effort is between those of the other two types. • Double-gimbal scissored-pair control-moment gyros (DGSPCMG) is considered. • Model-predictive control (MPC) based steering laws are designed for this system. • Fast maneuver, minimum control energy types, and hybrid of these two are considered. • Hybrid type achieved a short rise time of angular velocity and smooth stabilization. • As setting a long receding horizon length, the settling time was shortened. [ABSTRACT FROM AUTHOR]

Control Moment Gyro (CMG) and Reaction Wheel (RW) generally serve in different spacecraft control tasks due to their unique characteristics, such as large output torque and control accuracy, respectively. The major concerns in using of CMG and RW are singularity and saturation, which could make spacecraft uncontrollable. RW as singularity escape equipment is adopted to construct hybrid actuator system named CMG & RW (CMGRW) to enhance and improve the spacecraft attitude performance as well as the CMG's. First, the attitude dynamic model of the spacecraft equipped with hybrid actuators is established and the corresponding singularity is analyzed thoroughly. Then null motion in CMGRW is further argued and proved feasible for both elliptical and hyperbolic singularities escape. A new performance index in terms of CMG and RW state is proposed, followed by a steering logic using gradient method with a feasible null motion vector to drive the hybrid actuator system to feasible states. Numerical simulations with initial conditions considering CMG singularity and RW saturation are selected to demonstrate the excellent performance of the hybrid actuators during the entire large angle agile maneuvering process, resulting in a group of feasible final states of the CMGRW that serves as great initial conditions for the next agile maneuvering. [ABSTRACT FROM AUTHOR]

A bstract Taking advantage of the high manoeuvrability and the accurate pointing of the so-called agile satellites, an algorithm which allows efficient management of the operations concerning optical acquisitions is described. Fundamentally, this algorithm can be subdivided into two parts: in the first one the algorithm operates a geometric classification of the areas of interest and a partitioning of these areas into stripes which develop along the optimal scan directions; in the second one it computes the succession of the time windows in which the acquisition operations of the areas of interest are feasible, taking into consideration the potential restrictions associated with these operations and with the geometric and stereoscopic constraints. The results and the performances of the proposed algorithm have been determined and discussed considering the case of the Periodic Sun-Synchronous Orbits. [ABSTRACT FROM AUTHOR]