Periodic oscillations are observed in Newton's gravitational constant G that are contemporaneous with length of day data obtained from the International Earth Rotation and Reference System (IERRS). Preliminary research has determined that the oscillatory period of G is ≈ 5.9 years (5.899 ± 0.062 years). In this paper, the oscillations are shown to be concomitant with the Earth's distance from t...

The problem of determining minimum-fuel maneuver sequences for a four-spacecraft formation is considered. The objective of this paper is to find fuel-optimal spacecraft trajectories that transfer four spacecraft from an initial parking orbit to a desired terminal reference orbit while satisfying a set of constraints on the formation at the terminal time. Trajectories involving both one and two ...

n support of the National Aeronautics and Space Administration’s (NASA) Human Exploration and Operations Mission Directorate (HEOMD), the Space Launch System (SLS) is being designed for safe, affordable, and sustainable human and scientific exploration missions beyond Earth’s orbit (BEO). The SLS Team is tasked with developing a system capable of safely and repeatedly lofting a new fleet of spa...

Orbital stabilization of an underactuated cart-pendulum system is under study. The quasihomogeneous control synthesis is utilized to design a second order sliding mode controller that drives the actuated cart to a periodic reference orbit in finite time, while the non-actuated pendulum produces bounded oscillations. A modified Van der Pol oscillator is introduced into the synthesis as an asympt...

An assessment is presented of a Solar Polar Orbiter mission as a Technology Reference Study. The goal is to focus the development of strategically important technologies of potential relevance to future science missions. The technology is solar sailing, and so the use of solar sail propulsion is, thus, defined a priori. The primary mission architecture utilizes maximum Soyuz Fregat 2-1b launch ...

The Low Earth Orbit (LEO) satellite networks require a reliable handover re-routing protocol that is critical for connections with multihop intersatellite links (ISLs). In this paper, we introduce a footprint handover re-route protocol (FHRP) that maintains the optimality of the initial route without performing a routing algorithm after satellite handovers. Furthermore, the FHRP handles the int...

We predict from first principles an entirely topological orbital magnetization in the noncoplanar bulk antiferromagnet γ-FeMn originating in the nontrivial topology of the underlying spin structure, without any reference to spin-orbit interaction. Studying the influence of strain, composition ratio, and spin texture on the topological orbital magnetization and the accompanying topological Hall ...

We examine the spin-orbit coupling effects that appear when a wave carrying intrinsic angular momentum interacts with a medium. The Berry phase is shown to be a manifestation of the Coriolis effect in a noninertial reference frame attached to the wave. In the most general case, when both the direction of propagation and the state of the wave are varied, the phase is given by a simple expression...

The planning of space missions to planets and small Solar-System bodies often requires numerous simulations in order to quantify the relative scientific value of various flyby geometries. Here, using the Born approximation for the unperturbed reference orbit, we describe a new perturbation theory for flyby orbits. Results are expressed in terms of the Doppler shift induced in the frequency of a...

In this work, a Lyapunov-based synthesis and control design to induce periodic motion in a unicycle-type wheeled mobile robot (wmr) is under study. The solution of a second-order dynamical system is used as desired trajectory to achieve orbital stabilization. The selected dynamical reference system exhibits a limit cycle behavior which allows to move from one orbit to another by simply changing...