Based on the context and the answer, generate a question. 

Context: The astronauts did n't get paid extra for being astronauts -- they just got the salary that any other military officer of their rank got . Though space flight was temporary duty , which was paid per diem . The rate at that time was $ 25 per day , which would have been $ 275 for the 11-day mission . But since meals were furnished , that was deducted .

Answer:

They are doing a service to their country .



Why would the astronauts not get additional pay ?