This is challenging the church leaders to take action against racial injustice because it is trying to convince them what they are doing is wrong. Martin states "Injustice must likewise be exposed, with all of the tension its exposing creates to the light of human conscience and the air of national opionion before it can be cured." This shows that he is trying to push justice everywhere by calling out the mistakes of others and trying to help them dix their injustice.
The word astronauts in the sentence is functioning as the direct object.
Direct objects are often a noun phrase that refers to a person or thing that <u>receives</u> the action of the verb. In order to spot a direct object within a sentence, remember to ask yourself “who” or “what” is receiving the action. The answer in this case would be: <em>"the austronauts". </em>
