Sentence:  The astronauts, played here by an ensemble of square jaws and <WSD>baby faces</WSD> (including Jason Clarke, Patrick Fugit, Christopher Abbott, Ethan Embry, and Corey Stoll as a hilariously tactless Buzz Aldrin), had to be scientists and athletes, subjecting themselves to spinning, nausea-provoking simulators one day, basic rocket physics the next. 
Meaning of the word marked with <WSD> tags:  A person having such a face, especially a young man having a beardless appearance.