 According to Thorne, the element which has the highest degree of artistic freedom is the clouds of ice on one of the planets they visit, which are structures that would go beyond the material strength that ice could support.Astrobiologist David Grinspoon criticized the dire "blight" situation on Earth portrayed in the early scenes, pointing out that even with a voracious blight it would have taken millions of years to reduce the atmosphere's oxygen content.He also notes that gravity should have pulled down the ice clouds.