Rates have roller-coastered through two peaks and troughs in the past decade, and when the bottom of the current trough will be reached is anybody's guess.
"It's anybody's guess what the developments will be from this point on, " said Theodore Couloumbis, professor emeritus in international relations at the University of Athens.
Whether the Astrium system will remain a specialised novelty or will be the forerunner of something more like the cosmic power stations of Asimov's imagination is anybody's guess.