 Why can't Lieutenant Britton go back to Earth?
There, high in the emptiness of space, Space Station One swung in its orbit. Once every two hours, the artificial satellite looped completely around the planet, watching what went on below. Outside its bright steel hull was the silence of the interplanetary vacuum; inside, in the hospital ward, Lieutenant Alice Britton clutched at the sheets of her bed in pain, then relaxed as it faded away. "Lieutenant Britton, it is my personal opinion that you need your head examined, and not by a general practitioner, either! The terrible pressure of a rocket landing would increase her effective body weight to nearly half a ton; an adult human being couldn't take that sort of punishment for long, much less the tiny life that was growing within her.
 The G-forces the body is subjected to during space travel would affect the fetus.
 There are no ships available to go to Earth at this time.  There is no one else trained to replace her as Chief Radar Technician on the space station.  The replacement Radar Technician was killed in a car wreck on his way to White Sands. A new technician will have to be trained.  The G-forces the body is subjected to during space travel would affect the fetus.