Formation Flying is the concept that multiple spacecraft can be arranged in a formation to perform tasks that are not possible with a single spacecraft, or tasks that can be done more efficiently or inexpensively with a group of small spacecraft. One of the main engineering problems to be overcome is that of orienting or pointing a spacecraft to a very high degree of precision. Many approaches ...

This paper establishes a dynamics model for deploying solar panels with clearances by using a practical method and provides a useful way to identify the effects of clearances on spacecraft systems. Considering the clearance of joints, a contact dynamic model is established using the nonlinear spring-damp model and the friction effect is considered by using the Coulomb friction model. Based on t...

In this paper, two different algorithms are presented for the estimation of spacecraft body angular rates in the absence of gyro rate data for a star tracker mission. In first approach, body angular rates are estimated with the spacecraft attitude using a dynamical model of the spacecraft. The second approach makes use of a rapid update rate of star camera to estimate the spacecraft body angula...

This paper describes a novel concept for laser-based interrogation, communication, and navigation between multiple spacecraft platforms using a gimbaled laser source on a pursuer spacecraft and a target board populated with retromodulators (modulating retroreflectors) integrated on a host spacecraft. The combined laser source and retroreflectors can provide centimeter-level relative positioning...

The Grad-Shafranov (GS) reconstruction technique, a single-spacecraft based data analysis method for recovering approximately two-dimensional (2-D) magnetohydrostatic plasma/field structures in space, is improved to become a multi-spacecraft technique that produces a single field map by ingesting data from all four Cluster spacecraft into the calculation. The plasma pressure, required for the t...

Recent multi-spacecraft studies of solar wind discontinuity crossings using the timing (boundary plane triangulation) method gave boundary parameter estimates that are significantly different from those of the well-established single-spacecraft minimum variance analysis (MVA) technique. A large survey of directional discontinuities in Cluster data turned out to be particularly inconsistent in t...

This paper presents a method for safe spacecraft autonomous maneuvering that leverages robotic motion planning techniques to spacecraft control. Specifically, the scenario we consider is an in-plane rendezvous of a chaser spacecraft in proximity to a target spacecraft at the origin of the Clohessy-Wiltshire-Hill frame. The trajectory for the chaser spacecraft is generated in a receding-horizon ...

In this paper, a nonlinear trajectory control algorithm of rendezvous with maneuvering target spacecraft is presented. The disturbance forces on the chaser and target spacecraft and the thrust forces on the chaser spacecraft are considered in the analysis. The control algorithm developed in this paper uses the relative distance and relative velocity between the target and chaser spacecraft as t...

A recently developed technique for reconstructing approximately two-dimensional (∂/∂z≈0), timestationary magnetic field structures in space is applied to two magnetopause traversals on the dawnside flank by the four Cluster spacecraft, when the spacecraft separation was about 2000 km. The method consists of solving the GradShafranov equation for magnetohydrostatic structures, using plasma and m...

The research presented in this report focuses on the spacecraft simulators, Whorl-I and Whorl-II, in the Space Systems Simulation Laboratory (SSSL) at Virginia Tech. The goal of this research is to develop a program to visualize the attitude of the simulators in real-time through Analytical Graphics Inc.’s Systems Tool Kit (STK). Spacecraft missions are high-risk and highexpense; therefore, ext...