Why do we want to go to another star anyway? We obviously must want to do it pretty badly, or we would never pay for all this. Presumably this isn't some kind of cold war stunt like Apollo, where we go plant a flag and come home and drop it all. We certainly aren't likely to get any immediate financial benefit. We absolutely don't have any problems back home (hunger, famine, mineral depletion, etc..) that this could help. So what do we want to get out of the flight?
€Very popular idea with public.
€Possibility of tremendous scientific returns.
Disadvantages
€Expensive. You'd need a huge ship to carry all of the hundreds of researchers, surveyors, and all the support staff and advanced equipment it would take to do even a minimal job of surveying a new star system.
€A planet with a Earth-like ecology it would be a biological death trap. Alien microbes, allergens, and other unknowns life forms would easily defeat unprepared Earth mammalian immune systems. The ground teams would be in an area that would be worse, to them, than biological war back on Earth.
€On a planet with a non-Earth-like ecology it still could be a biological death trap, and in addition have basic climate and biosphere incompatibilities (Wrong temperatures, air pressures, gravity).
€This is a massive undertaking. You'd only try it if you really wanted to explore. This would require a major national (or international?) commitment.
€Very popular idea with public.
€Excellent staging area for direct examination of that planet or moon.
Disadvantages
€Expensive. Either the colony would need to be the size of a major city to support all of the specialists needed to support a self sustaining society, or regular (extremely expensive) supply flights from earth would be necessary.
€On a planet with a Earth-like ecology it would be a biological death trap. Alien microbes, allergens, and other unknowns life forms would easily defeat unprepared Earth mammalian immune systems.
€On a planet with a non-Earth-like ecology it still could be a biological death trap, and in addition have basic climate and biosphere incompatibilities (Wrong temperatures, air pressures, gravity).
€Isolation from resources. Ores, energy and raw materials are far harder to access on a planet than in space.
€Isolation from other planets.
€Their doesn't seem to be enough practical justification for such a massive undertaking. Again, it would require a major commitment or resources. Which means a major public interest.
€Still may be a very popular idea with public.
€Excellent staging area for examination of the solar system.
€Much lower biological threat than on a planet with biosphere.
€The internal gravity, radiation, and environment can be precisely tailored to humans.
€Far easier to construct and service than a planet bound colony.
€Easy access to plentiful resources. (Space is considered so much richer in cheap, easy to access resources and power. That it is expected that Earth's heavy industry will migrate into space in the next century.)
€Could act as a servicing center and supply port for the starship, or subsequent starships.
Disadvantages
€Expensive. Either the colony would need to be the size of a major city to support all of the specialists needed to support a self sustaining society, or regular (extremely expensive) supply flights from earth would be necessary.
€Their doesn't seem to be enough practical justification for such a massive undertaking. Again, it would require a major commitment or resources. Which means a major public interest.
€This could establish facilities necessary for routine, lower cost, flights between home and this starsystem.
Disadvantages
€Construction could take so many resources that little or no exploration will be done.
€Less interesting to public than an exploration or colony program. So it might have a harder time getting funded. But it could be part of a first flight the opens up the star system for larger follow on flights.
€Could be very expensive.