Last Monday my colleague Marc Twining, Senior Geologist with Iluka Resources Ltd, spoke to my Indigenous Heritage Management class about how mining exploration and heritage intersect. Iluka principally mine heavy mineral sands (HMS). Now I've done my research, so was well aware that these minerals (like rutile and ilmenite) end up in white pigments - paint, ceramics - this is why toilet bowls are so shiny and white! - but when Marc mentioned titanium being extracted from HMS, I made an obvious connection that had escaped me before.
Titanium is a metal very important to spacecraft manufacture. Pressurant tanks are usually made from it, and the USSR Venera series, which had to withstand the high pressures and temperatures of the Venusian surface, were constructed around titanium shells.
So there is, to my mind, a lovely symmetry here. Titanium is extracted from HMS on ancient beaches far below the present surface of the Earth, made into spacecraft which enter Low Earth Orbit, and when those spacecraft re-enter the Earth's atmosphere, the titanium spheres survive and fall back to Earth. If undiscovered, they may well become buried in their turn .....
This is my terrestrial/celestial dynamical system in action, complete with taphonomy.