Geologists had already discovered much about the chemical composition of primordial Earth.

Discipline was a seeder ramship, targeted for a ring of yellow stars that might host worlds like the primordial Earth.

Or something far greater, far more permanent, like poisoning the atmosphere of primordial Earth, or simply murdering the first hominids to arise?

Fox believed in spontaneous generation of life and suggested that his experiments possessed conditions that were similar to those of primordial Earth.

The experiment was meant to resemble the drying-out of amino acids in similar conditions to those of primordial Earth.

Some believe it is unlikely that primordial Earth had such a distribution of amino acids available on its surface.

No signs of life at all; it might as well be the primordial Earth.

Suit people up in environment suits and take them for a stroll on 'the primordial Earth.'

The conditions of primordial Earth would have returned.

One of the mission's major objectives is the investigation of Titan's environment, thought to be a frigid version of conditions on the primordial Earth.