Open source software tools have been gaining acceptance in the astrodynamics community for some applications, though heritage tools still dominate precision orbit determination and propagation. This paper examines recent tide modeling improvements in the open source Orbit Extrapolation Toolkit (Orekit) and compares it with the US Naval Research Laboratory’s (NRL) heritage Orbit Covariance Estim...

the low earth orbiting (leo) satellites are widely used for geosciences applications. for most applications, precise orbital information of the satellites is required. a combination of the in suite observations and dynamic orbit yields the optimum solution. in order to obtain the combined optimal solution, one needs to analytically or numerically propagate the state vector epoch by an epoch bas...

We study semiclassical approximations to the time evolution of coherent states for general spin-orbit coupling problems in two different semiclassical scenarios: The limit ~ → 0 is first taken with fixed spin quantum number s and then with ~s held constant. In these two cases different classical spin-orbit dynamics emerge. We prove that a coherent state propagated with a suitable classical dyna...

This paper demonstrates the use of polynomial chaos expansions (PCEs) for the nonlinear, non-Gaussian propagation of orbit state uncertainty. Using linear expansions in tensor-products of univariate orthogonal polynomial bases, PCEs approximate the stochastic solution of the ordinary differential equation describing the propagated orbit, and include information on covariance, higher moments, an...

Parameter errors in orbital models can result in poor orbit determination (OD) using a traditional Kalman filter. One approach to account for these errors is to consider them in the so-called Schmidt-Kalman filter (SKF), by augmenting the state covariance matrix (CM) with additional parameter covariance rather than additively estimating these so-called “consider” parameters. This paper introduc...

This paper describes the use of Murchison Widefield Array, a low-frequency radio telescope at radio-quiet Western Australian site, as radar receiver forming part continent-spanning multistatic network for surveillance space. details system geometry employed, orbit-specific signal processing, and orbit determination algorithms necessary to ensure resident space objects are detected, tracked, pro...

background: spermatogonial stem cells (sscs), a subset of undifferentiated type a spermatogonia, are the foundation of complex process of spermatogenesis and could be propagated in vitro culture conditions for long time for germ cell transplantation and fertility preservation. objective: the aim of this study was in vitro propagation of human spermatogonial stem cells (sscs) and improvement of ...

Orbits for satellites o f the Global Positioning System (GPS) have been determined with submeter accuracy. Tests used to assess orbit accuracy include orbit comparisons from independent data sets, orbit prediction, ground baseline determination, and formal errors. One satellite tracked for 8 hours each day shows rms errors below I m even when predicted more than 3 days outside of a 1-week data ...

Orbit determination and control problems are sometimes solved using linearized methods, even though nonlinear effects can sometimes dominate the system. This paper addresses ways to parallelize computational algorithms for numerical integrators and nonlinear relative motion equations. An application of the proposed methods to mutual gravitation of a fragmented asteroid is presented, with analys...