Thomas Mann believed in the power of perambulation: “Thoughts come clearly while one walks.” Not for three men and three women who, until this week, were incarcerated in a dome erected on a dormant volcano in Hawaii.

During eight months of voluntary confinement on the slopes of Mauna Loa, a walk outside meant donning spacesuits and grappling with airlocks — hardly a recipe for mental clarity but, instead, preparation for what life might be like in the first human settlement on Mars. The isolation experiment, which finished on Saturday and was funded by Nasa, was designed to examine the psychological challenges for strangers brought inescapably together in a hostile Martian environment, where venturing out unprotected in the carbon dioxide-rich atmosphere would lead to suffocation within three minutes.

The vista from the dome’s single porthole was not the garland-strewn paradise of honeymooners but a barren, silent landscape of lava fields and mountains. The group, led by Canadian engineer Martha Lenio, reported missing the sun and wind on their skin, a varied diet, long showers and seeing the world through visorless eyes. Dr Lenio staved off boredom by knitting, improving her French and learning the ukulele, writing in her blog: “It may actually be really weird to see other people again.” Disappointingly, the sextet still seem to be on jovial terms and have been enjoying the more familiar delights of Hawaii.