I am conjecturing that in the late 21st Century I gave put together in my fictional universe, we have moved past purely State-Sponsored space exploration. In this world, to defray the costs of vehicle construction and fitting out, a large part of the vessel is privately funded.
This is actually not that uncommon in our world. Take the case of the liner SS United States. The concept was that the ship was built using a Naval propulsion system. In peace time, it was an Ocean liner. In war time, it would become a support ship. Most likely a troop transport.
The environment in which the Iliad-07 was built is one of an uneasy peace between ISTO and the (former) Krasnovian Empire. The space race to reach nearby star systems ended in an unsatisfying draw.
The Krasnovians reached nearby systems first. But their ships lacked ammenties like fresh food that could sustain a colony long term. Their expansion depends on finding habitable planets. And so far... none have been found. ISTO was second. But they figured out how to fit an ecosystem in a ship.
Iliad-07 is a block-3 vessel. These are intended for indefinite voyages. They tow along the foundations for a colony in a remote system. Habitable planet, not required. Its colony would operate much like ISTO's current space holdings, extracting gas from comets and pulling heavier materials from proto-planets and asteroids.
Which systems to colonize, and what sorts of industries to set up are a bit more of a fuzzy subject. Space is big. Approaches to exploring it are legion. And anyone embarking on a journey out there had better be VERY comfortable with the idea, because they will be spending 20 years in transit, a few decades building the colony, and even if they took the first ship home, the Earth they returned to would be centuries in the future.
The system that arises is a little free-market, a little government sponsorship, a pinch of wishful thinking, and a ton of cooperation. In the society of a colonial ship, everyone "in the company" owns a portion of the ship. Not a cabin, or a hatch, or an engine. They own a share of the vessel.
Personal shares cannot be sold, traded, or given away. They are non-transferrable. These shares entitle on to a say over how the vessel is operated. A personal share is basically one's "citizenship". Parents can vote for their children's interests until the child reaches the age of majority.
As most potential colonists are not exactly rich (otherwise, why would they leave Earth?), there is also the need to fund a vessel's construction. The cost of the ship is covered by selling corporate shares. Those shares are purchased by governments, individual sponsors, and organizations. Corporate shares entitle one to a say on how the ship is built, where it will be going, what cargo it will be carrying, and what it will do when it gets there.
Sometimes a crew comes first and charter later. Sometimes the charter is first, and crews select a ship because of it. The process is a bit messy and fluid right up until the corporation takes delivery of the ship. At this point the ship's charter needs to be ratified by the crew, and the last of the expected payments made to the shipyard.
Iliad-07 was partially funded by having the ship serve as an Ice mining vessel before setting off to 18 Scorpii. After departing the shipyard and taking aboard the colonists, the ship travelled out to the Oort cloud. It spent a few months harvesting Deuterium from comets, and returning that finished fuel to the colonies in the Asteroid belt.
This trip doubled as a shakedown cruise. It also gave the on-board ecosystem an entire 2 years to establish itself. Crew got a sense of what life was like on board, and anyone who found that this wasn't for them had a chance to get off. The trip also gave engineers a sense of which parts tended to need more replenishment than projections had estimated, and stock enough parts for the journey ahead.
But first and foremost, it was a way to collect something that could be sold and the proceeds pay back the original investors of the ship. It also allowed the ship to collect the immense amount of fuel it would need for its longer journey for as near as makes no difference to free.
In Iliad-07's case, several Corporate shareholders were also Personal shareholders. And occasionally decisions get messy about whether an issue is something regarding operations (Personal shareholders) or mission (Corporate shareholders). The flipside is that because some rich people bought the ship as a sort of retirement village, it has a lot of nice amenities like an artificial beach, theaters, and an exquisite library.