habitation

Some of these have been hijacked and are unfit for human habitation.

"The building itself is hardly fit for long-term habitation: sheet metal walls, shoddy construction, the look and feel of a temporary warehouse rather than a permanent facility," Santos wrote.

"This was a literate, urban society where people had separate spaces for habitation, burial practices and industrial work," Mr Kumar says, noting it's the first large, well-defined ancient urban settlement found in southern India.

Verrelli spent nine years in Arizona, an arid environment where many organisms struggle to survive, but that has now been altered and made more hospitable by human habitation.

Lab-grown food, she said, could potentially be better for astronauts, as well as reduce costs to the levels required to make long-term off-world habitation viable.