How do modifiers add to a sentence? ?

A modifier in a sentence is useful to communicate any change, make clarifications, further explain or provide details about qualifies, or even set limits to a particular word in a in sentence.

Explanation: Having mentioned the characteristics above, modifiers can also serve to add emphasis. An example of modifiers are adjective clauses and adverbial phrases.

what is the context here? we need to know what story you're talking about : )

the apollo program, also known as project apollo, was the third united states human spaceflight program carried out by the national aeronautics and space administration (nasa), which succeeded in landing the first humans on the moon from 1969 to 1972.