Short-axis-mode rotation of a free rigid body by perturbation series

A simple rearrangement of the torque free motion Hamiltonian shapes it as a perturbation problem for bodies rotating close to the principal axis of maximum inertia, independently of their triaxiality. The complete reduction of the main part of this Hamiltonian via the Hamilton-Jacobi equation provides the action-angle variables that ease the construction of a perturbation solution by Lie transforms. The lowest orders of the transformation equations of the perturbation solution are checked to agree with Kinoshita's corresponding expansions for the exact solution of the free rigid body problem. For approximately axisymmetric bodies rotating close to the principal axis of maximum inertia, the common case of major solar system bodies, the new approach is advantageous over classical expansions based on a small triaxiality parameter.Comment: 22 pages, 1 figure, to be presented in 2013 AAS/AIAA Astrodynamics Specialist Conference, Hilton Head, South Carolina, August 11 - 15, 201

Efficient formulation of the periodic corrections in Brouwer's gravity solution

The periodic terms of Brouwer's gravity solution are reconstructed in a nonsingular set of variables which are derived from the well-known polar-nodal variables. This change does not affect the essence of the solution, which still keeps all the benefits of the action-angle variables approach, and yields two major improvements. Namely, the periodic corrections of Brouwer's solution are now valid for any eccentricity below one and any inclination except the critical inclination, and, besides, are significantly simpler than the nonsingular corrections in Lydanne's reformulation of Brouwer's theory.Comment: 19 page

A Hopf variables view on the libration points dynamics

The dynamics about the libration points of the Hill problem is investigated analytically. In particular, the use of Lissajous variables and perturbation theory allows to reduce the problem to a one degree of freedom Hamiltonian depending on two physical parameters. The invariant manifolds structure of the Hill problem is then disclosed, yet accurate computations are limited to energy values close to that of the libration points

MEMORANDUM: Quality Assurance of 2016 Great Bay Estuary Water Quality Data and 2017 Cocheco River and Bellamy River Water Quality Data collected by UNH

The purpose of this memorandum is to document the results of quality assurance checks on the 2016-2017 water quality data collected by UNH for the Great Bay National Estuarine Research Reserve (GBNERR) System-Wide Monitoring Program, GBNERR Diel Sampling, and UNH Tidal Water Quality Monitoring stations. These programs were previously established in the NHDES Environmental Monitoring Database with project identifiers of “NERRTWQ”, “NERRDIEL”, and “JELTWQ”, respectively. UNH/GRB NERR reviewed these data to ensure that they met data quality objectives for the National Estuarine Research Reserve and its partners

Intermediary LEO propagation including higher order zonal harmonics

Two new intermediary orbits of the artificial satellite problem are proposed. The analytical solutions include higher order effects of the Geopotential, and are obtained by means of a torsion transformation applied to the quasi-Keplerian system resulting after the elimination of the parallax simplification, for the first intermediary, and after the elimination of the parallax and perigee simplifications, for the second one. The new intermediaries perform notably well for low earth orbits propagation, are free from special functions, and result advantageous, both in accuracy and efficiency, when compared to the standard Cowell integration of the J2 problem, thus providing appealing alternatives for onboard, short-term, orbit propagation under limited computational resources.Comment: Celestial Mechanics and Dynamical Astronomy: Accepted September 25, 201