Space robotics has a substantial interest in achieving on-orbit satellite servicing operations autonomously, e.g. rendezvous and docking/berthing (RVD) with customer and malfunctioning satellites. An on-orbit servicing vehicle requires the ability to estimate the position and attitude in situations whenever the targets are uncooperative. Such situation comes up when the target is damaged. In this context, this work presents a robust autonomous pose system applied to RVD missions. Our approach is based on computer vision, using a single camera and some previous knowledge of the target, i.e. the customer spacecraft. A rendezvous analysis mission tool for autonomous service satellite has been developed and presented, for far maneuvers, e.g. distance above 1 km from the target, and close maneuvers. The far operations consist of orbit transfer using the Lambert formulation. The close operations include the inspection phase (during which the pose estimation is computed) and the final approach phase. Our approach is based on the Lambert problem for far maneuvers and the Hill equations are used to simulate and analyze the approaching and final trajectory between target and chase during the last phase of the rendezvous operation. A method for optimally estimating the relative orientation and position between camera system and target is presented in detail. The target is modelled as an assembly of points. The pose of the target is represented by dual quaternion in order to develop a simple quadratic error function in such a way that the pose estimation task becomes a least square minimization problem. The problem of pose is solved and some methods of non-linear square optimization (Newton, Newton-Gauss, and Levenberg-Marquard) are compared and discussed in terms of accuracy and computational cost.

Using the Earth albedo model and the orbital dynamics model developed as part of the First Look Project (Fast Initial In-Orbit Identification of Scientific Satellites) the terrestrial albedo is evaluated considering the orbits of some scientific missions as Gravity Probe B, MICROSCOPE and STEP. The model of the Earth albedo is based on the reflectivity data measured by NASA's Earth Probe satellite, which is part of the TOMS project (Total Ozone Mapping Spectrometer). The reflectivity data are available daily, on line at the TOMS website, and they fluctuate because of changes in clouds and ice coverage and seasonal changes. The data resolution partitions the Earth surface into a number of cells. The incident irradiance on each cell is used to calculate total radiant flux from the cell. With the radiant flux from each cell, the irradiance at the satellite is calculated.

The goal of the present paper is to study the problem of station keeping maneuvers of satellites that belong to a constellation. The objective is to perform those maneuvers with low fuel consumption and but also including a time constraint. This type of problem has several aspects to be considered, like fuel consumption, duration of the maneuvers. These aspects are applied to all the satellites of the constellation, so a strategy has to be found to consider the global optimization of those variables that can control the geometry of the constellation. So, this is a multiobjective problem. To find a solution, strategies are formulated that minimize the fuel consumption considering all the satellites and also considering the duration of the maneuver. Numerical examples are shown.

One issue the design team has to face in the process of building a new spacecraft, is to define its mechanical and electrical architecture. The choice of where to place the spacecraft´s electronic equipment is a complex task, since it involves simultaneously many factors, such as the spacecraft´s required position of center of mass, moments of inertia, equipment heat dissipation, integration and servicing issues, among others. Since this is a multidisciplinary task, the early positioning of the spacecraft´s equipment is usually done "manually" by a group of system engineers, heavily based on their experience. It is an interactive process that takes time and hence, as soon as a feasible design is found, it becomes the baseline. This precludes a broader exploration of the design space, which may lead to a suboptimal solution, or worse to a design that will have to be modified later. Recently, it has been shown the potential benefits of automating the process of spacecraft´s equipment layout using optimization techniques. In this paper, a prototype of an Excel ® based tool for multidisciplinary spacecraft equipment layout conception is described. Provided the geometric dimensions, mass and heat dissipation of the equipment, and the available positioning area, the tool can automatically generate many possible trade-off solutions for the layout. It allows the user to set specific equipment to specific areas of positioning, and different combinations of objective functions can be used to drive the design. The features of the tool are shown in a simplified three dimensional problem.