Swiss scientists have apparently discovered an efficient method to learn a foreign language. The method works as follows: first the scientist gave German-speaking students a number of pairs of German words and their Dutch translation, while awake. Then they repeated these pairs while the students were asleep. Those students who heard the pairs in their sleep, were better in remembering the Dutch words than the students in the control group.
This research is of interest for space settlers. In The High Frontier O’Neill already understood the need for space settlers to learn multiple languages as Russian and Japanese (for American colonists) while on their way to L5, in order to improve communication with settlers from other nations.
We have suggested on this site that space settlements should consider a constructed language as official language in order to deal with a multi-ethnic population. Regardless of what option is chosen, space settlers have to learn some other language.