Magrathea: The wealthiest planet in the universe, legendary for custom-building luxury planets for ultra-rich clients. When the galactic economy collapsed, Magrathea went into hibernation. By Arthur's time, most people think it's a myth.
Slartibartfast: A Magrathean planet designer, coastline specialist. Won an award for designing Norway's fjords - he's quite proud of this. Matter-of-fact craftsman doing cosmic-scale work.
The reveal he delivers to Arthur: Earth wasn't a natural planet. It was commissioned by mice (the actual intelligent species - humans were part of the computational matrix) as a giant computer to calculate the Ultimate Question. Deep Thought had calculated the Ultimate Answer (42) but needed Earth to figure out what question would produce that answer. The program would take 10 million years. Earth was five minutes from completion when the Vogons destroyed it.
Magrathea is now building Earth Mark II, but Slartibartfast knows it won't work - you can't just rerun the experiment. The original context is gone, Arthur's brain supposedly has fragments of the question in it, but extracting it would destroy what makes him Arthur.
Some further thoughts on the idea of rebooting and care.
Prevention matters more than restoration because restoration is often impossible. You can't bring back extinct species. You can't recreate 10 million years of evolutionary accidents. You can't rebuild the cultural context once it's destroyed.
This makes the stakes real without making them paralyzing - you're not facing inevitable doom, you're facing the necessity of care. The absurdist humor gives you the emotional tools to look at that honestly, but Douglas isn't letting you off the hook. Some things, once lost, are lost.
Last Chance to See takes the same structure without the science fiction buffer. Real species, really disappearing, often because of bureaucratic processes (habitat destruction for development - Vogons building bypasses). The kakapo, the Yangtze river dolphin. You can't reboot them.
The lesson isn't despair, it's attention and care. Douglas gives you permission to laugh at the absurdity while insisting you take responsibility for what you can actually protect.