This chapter is devoted to population orbit determination, that is not just computing the orbit for a single object, but compiling a catalog of orbits given a large number of observations. A survey is a project aiming at collecting observations of the largest and most representative sample of objects possible. We deal here only with the case in which the target population belongs to the Solar System; of course an astronomical survey may target simultaneously extrasolar populations. We deal with Earth satellites in Section 8.7. This chapter is based on our papers (Milani et al. 2005a, Milani et al. 2008, Milani et al. 2006) and ongoing research, in particular that in preparation for Pan-STARRS, a next-generation survey.

Operational constraints of Solar System surveys

The following three arguments should be taken into account in the definition of an identification/orbit determination procedure for a modern sky survey.

First, Moore's law tells us that the number of elements in an electronic chip grows exponentially with time; the doubling time has been around 18 months for more than 30 years. There is no indication that this trend might slow down; although in the last few years it has no longer been possible to increase the clock frequency, the increase in the complexity of the chips is now used to produce “multicore” CPUs. Assuming the multicores are used in an efficient parallelization procedure, the practical performance of computers continues to increase by a factor of 4 every three years.