2007 Volume 20 Issue 5 Pages 205-215
Recently, the risk that garbages in space (space debris) conflict with a running space satellite or fall to the ground is increasing. To prevent the accident beforehand the Japan Aerospace Exploration Agency observes the space debris by a single radar whose operation plan is obtained by a heuristic technique. However, since the technique does not use global information of a prediction of the space debris orbit, the plan is far from the optimum. In this paper we propose a new technique using the global information. The method obtains an ordering of an observation of the debris on the basis of the longest path of a graph whose nodes corresponds to the debris. The number of nodes of the longest path provides an upper bound of the optimum. We experimented the proposed technique for actual prediction data. The results showed that the proposed technique can make a plan that observes twice the space debris than those of the existing technique, and that the differences from the upper bound are 0 or 1.