This story is also a rare example of the Doctor returning to a location where he has saved the day to see what the lasting consequences of his actions are. The entire story is apparently wrapped up by the end of episode two, with the Doctor having cured the disease, wished the colonists farewell and returned to the TARDIS.
But in part three, the TARDIS lands on the same ship 700 years later, to find that the Monoids are now the ship’s overlords…
The Ark in Space (Season 12, 1975)
A few regenerations later the Doctor runs into another Ark, the Space Station Nerva, floating in orbit around Earth with a collection of frozen humans and a massive alien insect. The Earth has been rendered uninhabitable again by humanity’s oldest enemy, the sun.
As far as destructions of the Earth go, this one was temporary (even by the time they transmat down to the planet in the next story, “The Sontaran Experiment”, there is already grass down there), but it also had the most far-reaching implications. It is implied that not just Space Station Nerve, but also the Starship UK in “The Beast Below”, and the Erehwon from “Smile” were refugees of this solar flare emission in particular. Even Tom Baker’s own “The Sun Makers”, which sees humanity relocated to Pluto, has Earth rendered uninhabitable by solar activity.
The Pyramids of Mars (Season 13, 1975)
When the Fourth Doctor encounters Sutekh the Osirian, the Ancient Egyptian God of Death, Sarah Jane Smith is sceptical that the God is all that. After all, the year is 1911, and Sarah Jane would have remembered reading about the Sutekh killing everyone in the history books.
The Doctor considers explaining the butterfly effect, the many worlds theory of quantum mechanics, and the fluid and changeable nature of spacetime. He doesn’t have the attention span for that, so instead he takes Sarah Jane back to her home era of 1980, and shows her what it looks like. 1980 is a barren, hopeless desert completely inhospitable to life – and not just because Margaret Thatcher is Prime Minister.
