The program ss_9b.f90 was written for two reasons.
Firstly, there is a suggestion that the gravitational field of Jupiter acts as a shield which protects the inner planets from asteroid impacts. Some of our colleagues wanted a simulation of the Solar System so that they could shoot asteroids in from the Oort Cloud and see what (if anything) they hit. They could experiment with the size and position of Jupiter to see how important it is. This has implications for the probablity of the evolution of life elsewhere in the Universe. It may not be sufficient to have an Earth sized planet at the right distance from a star. We may need a Jupiter as well. ss_9b.f90 is a first step towards this simulation.
Secondly, we needed a test program for an experimental high performance computer using very fine-grain parallelisation. The project is described in "APPRASE: Automatic parallelisation of Fortran to run on an FPGA" Farrimond B.T., Collins J. and Sharma A. 2008, Paper presented at The Summer Conference of the Society for Computer Simulation, Edinburgh, Scotland, June 2008, and in "Towards a many-core architecture for HPC",Wyngaard J, Inggs M, Collins J and Farrimond B, 2013, 23rd International Conference on Field Programmable Logic and Applications (FPL).