Answer: We study other star systems in spaceships and big, professional telescopes
Shipping technologies and cultures were more readily shared
I believe all of the anwers apply.
The 'fewer natural resources" is applicable assuming they are currently depleting their natural resources.
A nonrenewable resource<span> is a </span>resource<span> of economic value that cannot be readily replaced by natural means on a level equal to its consumption. Most fossil fuels, such as oil, natural gas and coal are considered </span>nonrenewable resources<span> in that their use is not sustainable because their formation takes billions of years.</span>
