Planet Crossing Asteroids and Parallel Computing: Project Spaceguard
The orbits of the asteroids crossing the orbit of the Earth and other planets are chaotic and cannot be computed in a deterministic way for a time span long enough to study the probability of collisions. It is possible to study the statistical behaviour of a large number of such orbits over a long span of time, provided enough computing resources and intelligent post processing software are available. The former problem can be handled by exploiting the enormous power of parallel computing systems. The orbit of the asteroids can be studied as a restricted (N+M)—body problem which is suitable for the use of parallel processing, by using one processor to compute the orbits of the planets and the others to compute the orbits the asteroids. This scheme has been implemented on LCAP-2, an array of IBM and FPS processors with shared memory designed by E. Clementi (IBM). The parallelisation efficiency has been over 80%, and the overall speed over 90 MegaFLOPS; the orbits of all the asteroids with perihelia lower than the aphelion of Mars (410 objects) have been computed for 200,000 years (Project SPACEGUARD). The most difficult step of the project is the post processing of the very large amount of output data and to gather qualitative information on the behaviour of so many orbits without resorting to the traditional technique, i.e. human examination of output in graphical form. Within Project SPACEGUARD we have developed a qualitative classification of the orbits of the planet crossers. To develop an entirely automated classification of the qualitative orbital behaviour -including crossing behaviour, resonances (mean motion and secular), and protection mechanisms avoiding collisions- is a challenge to be met.
KeywordsParallel Computing Shared Memory Orbital Element Close Approach Chaotic Orbit
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- Clementi,E., Dietrich, J., Chin, S., Corongiu, G., Folsom, D., Logan, D., Caltabiano, R., Carnevali, A., Helin, J., Russo, M., Gnudi, A. and Palamidese, P. (1986) Large scale computations on a scalar, vector and parallel Supercomputer, IBM Technical report, KGN-77 Google Scholar
- International Business Machines Corporation (1988) Parallel FORTRAN. Language and Library reference. Pubblication SC23–0431–0Google Scholar
- Marsden, B.G., (1986) Catalogue of orbits of unnumbered minor planets (second edition). Minor Planet Center, SAO, Cambridge MA.Google Scholar
- Milani, A., Carpino, M. and Logan, D. (1988a). Project Spaceguard. Paraller Computation of Planet-Crossing Asteroid Orbits Advances in Parallel Computing, in pressGoogle Scholar
- Milani, A., Carpino, M., Hahn, G. and Nobili, A.M. (1988b) Project Spaceguard: Dynamics of planet-crossing asteroids. Classes of orbital behaviour Icarus, in pressGoogle Scholar
- Newhouse, S.E. (1980) in Dynamical Systems, Marchioro, C. ed., Liguori pub., NapoliGoogle Scholar
- Nobili, A.M. (1989) Celest. Mech., this issueGoogle Scholar
- Nobili, A.M., Milani, A. and Carpino, M. (1988) Fundamental frequencies and small divisors in the orbits of the outer planets, Astron. Astrophys.,in pressGoogle Scholar
- Shoemaker, E.M., J.G. Williams, E.F. Helin, and R.F. Wolfe (1979). Earth-crossing asteroids: Orbital classes, collision rates with Earth and origin. In Asteroids ( Shoemaker, E.M., J.G. Williams, E.F. Helin, and R.F. Wolfe, Ed.), pp. 253–282, Univ. of Arizona PressGoogle Scholar
- Snowbird, (1988) Global catastrophes in earth History; Proceedings of the secondGoogle Scholar
- Snowbird conference of Impacts, Volcanism, and Mass Mortality, Burke et al. eds., in pressGoogle Scholar
- Sussman, G.J. (1989) Celest. Mech.,this issueGoogle Scholar