This is the CRD (Campaign Reference Document) for the Classic Traveller campaign.
Classic Traveller is one of the original sci-fi RPGs, released around the time of the original D&D boxed set.
In Traveller you're a space Traveller who visits worlds and goes on adventures.
In the beginning you're scraping by to makes ends meet while buying/hitching rides to new worlds.
Eventually you scrape up enough to get your own starship to make the big money... but it comes with a hefty mortgage payment, requiring you to take on larger, risky adventures.