Biofuels could generate and store energy for long-term human habitation and exploration.

The structures are mostly ornamental (as in the case with ice castles), and not practical for long-term habitation.

"So now we have evidence that there was at least some long-term habitation of the surface," said Jade Dinh.

The land is mostly steep, rocky, semi-arid except for the narrow canyons, and inaccessible, making long-term habitation a challenge.

The full 60-metric ton "space station" has been delayed to 2020-2022, and will support three astronauts for long-term habitation.

Unmanned cargo spacecraft will dock with the station, allowing for resupply and long-term human habitation.

Few signs of long-term human habitation have been found.

He is chiefly remembered for his work addressing the long-term human habitation of space.

The site has no midden piles, nothing to indicate any long-term habitation.

Despite this, it is likely that the long-term habitation of the site had its roots in the late Bronze Age.