@tjbutt58 @Natasha_Jay She made a bunch of smart decisions, particularly early in Alien.

Ripley: Wait a minute. If we let it in, the ship could be infected. You know the quarantine procedure. Twenty-four hours for decontamination.
Dallas: He could die in twenty-four hours. Open the hatch.
Ripley: Listen to me, if we break quarantine, we could all die.