The scientists have returned with a bold agenda. The explorers are rescued unharmed but there's been a change in the relationship between the woman and the man who introduced our story.
A colossal project is started to revive the planet's ancient biosphere. Deep holes are dug into the mantle and giant explosions set off, the atmosphere is enriched with the help of comets and asteroids, and the temperature warms significantly.
The travelers stir first and come to life, reviving their eternal three way discussion. Finally, Planet emerges from a deep slumber and finds that Sky is returning as well.