The COMET program is a program for the collection of micron to submicron interplanetary dust particles in low Earth orbits. Since collection takes place as the Earth crosses a given meteor stream, the particles are mainly of cometary origin. The grain remnants, located at their impact positions on high purity metallic collectors, are analysed in the laboratory for chemical and isotopical identification. The COMET-1 experiment took place in 1985 October, during encounter with the Draconid meteor stream, related to the Giacobini-Zinner comet. The fluence of extraterrestrial grains that had impacted our detectors was approximately 10x higher than the value of the mean meteroid fluence at approximately 1AU, which suggests that most of the grains originated from the Giacobini-Zinner comet. One of the most important results of their chemical analysis was that approximately 90% of them are enriched in low Z elements (C and O have undoubedly been identified). They could contain a CHON phase similar to that observed in the close environment of Halley's nucleus. The first imagery of the grain remnants by field emission scanning electron microscopy suggests that they are very law density aggregates still present at the impacting positions which, in most cases, are very different from the impact craters observed for the same mean relative velocity for full grains of the same size. These results show that the COMET program has constituted an important step towards the analysis of cometary material and the understanding of the evolution of the early Solar System.

We describe an image-processing equipment designed and built to meet the specific requirements of an astrophysical experiment, but having probably useful applications in other fields of science and technology. It locates and makes the inventory of specified micrometer-sized holes in thin metallic films. The data acquisition is made by a CCD camera looking at the film through an optical microscope. The information goes to a microcomputer through a special interface. The program and the electronics were designed for optimum acquisition speed, automatic operation, and minimum need for human intervention.