Mercury - A New Software Package for Orbital Integrations

J.E. Chambers, F. Migliorini (Armagh Observatory)

We present Mercury: a new general-purpose software package for carrying out orbital integrations for problems in solar-system dynamics. Suitable applications include studying the long-term stability of the planetary system, investigating the orbital evolution of comets, asteroids or meteoroids, and simulating planetary accretion.

Mercury is designed to be versatile and easy to use, accepting initial conditions in either Cartesian coordinates or Keplerian elements in ``cometary'' or ``asteroidal'' format, with different epochs of osculation for different objects. Output from an integration consists of either osculating or averaged (``proper'') elements, written in a machine-independent compressed format, which allows the results of a calculation performed on one platform to be transferred (e.g. via FTP) and decoded on another. Mercury itself is platform independent, and can be run on machines using DEC Unix, Open VMS, HP Unix, Solaris, Linux or DOS.

During an integration, Mercury monitors and records details of close encounters, sungrazing events, ejections and collisions between objects. The effects of non-gravitational forces on comets can also be modelled. Additional effects such as Poynting-Robertson drag, post-Newtonian corrections, oblateness of the primary, and the galactic potential will be incorporated in future. The package currently supports integrations using a mixed-variable symplectic routine, the Bulirsch-Stoer method, and a hybrid code for planetary accretion calculations; with Everhart's popular RADAU algorithm and a symmetric multistep routine to be added shortly.

Our presentation will include a demonstration of the latest version of Mercury, with the explicit aim of getting feedback from potential users and incorporating these suggestions into a final version that will be made available to everybody.