Although the erosive effects of traveling between stars may be significant for future, high-speed interstellar spacecraft, they are anticipated to be negligible for the relatively slow-moving present-day vehicles (see interstellar probes) that are leaving the solar system. This is relevant when considering the future prospects for the Pioneer plaques and Voyager interstellar records. Most of the degradation that these externally mounted messages will suffer has probably already occurred during their departure from the comparatively dusty environs of our own planetary system. In interstellar space, where the average density of particles is about one trillionth the density of the best vacuum that can be produced on Earth, the wear and tear on spacecraft is expected to be very much less.