What you want is speed,
with minimal resource spent.
Be it equipment/HR.
And I think my method is it.
This can spread out to
different planets.
Understanding
and application of
electromagnetic shielding
is one of the key
factor in spreading out
into the universe i think.
If the ship can shield
itself from the explosion.
Power of the explosion
is never limited by
propulsion of any rockets.
How did the universe expand
itself in the first place is
my thinking.
Likewise, electromagnetic
shielding on cities will
help against radiation
as well. (Per city)
If one can manipulate
how it is distributed.
But ideally, the planet itself,
should have a protective barrier...
That is to naturally enhance
its magnetosphere...
(by use of laser hopefully)