Pros
Exploring the unknown
Developing technology
Testing and experimenting with unknown aspect in physics -
Creating new theories
Cons
Other issues are more important
Can be a waste of money if theories can be validated
There are dangers and risk that are unknown in space
Hope it helps
When it comes to the us becoming a imperial power, their main goal was economic expansion. now their ideals were good but since they started being an imperial power the economy has gone rather worse. so to answer your question their goals were good not have not been achieved.
History was a driving force behind such migration, since humans tended to move to new territory when they lacked food, shelter, or other resources--meaning that most of the conflicts throughout history have been driven by the same forces that drove migration out of Africa.
Paying the price for you beliefs
Remembering the horror
The living dead
Into the age of deception
The debt caused Britain to tax the colonists, which made the colonists angry
