At http://phys.org/print386851767.html … where did the two satellites of Mars come from, Phobos and Deimos. They were made famous by Velikovsky as the 'steeds of Mars' running before the planet as it supposedly passed close to the Earth. It has long been thought they are asteroids that have been captured by Mars at some point in its history. A paper in the July Astrophysical Journal rules out the capture hypothesis and plumps for a giant collision – read Worlds in Collision (but suitably dated in the very remote past). Was Velikovsky before his time? He could have had a banquet dipping into and out of some of the modern day hypothesis that have been appearing in recent years. Another version of the impact idea, by another group of scientists, is in July's Nature Geoscience. Here is an artist's idea of what occurred – and remember Velikovsky did not have a collision, in spite of the title of the book, but a fly-by (a close shave mind you) …
The proof of the pudding will come in 2022 when the Japanese may pluck out a plum. In that year they plan to launch a mission to Phobos in order to take samples.