Your question relates to the role of suspense in the story and how it is created and sustained throughout to make us literally sit on the edge of our seats and want to keep on reading right up until the very end of the short story. What adds greatly to the suspense is the way that the opening of this futuristic short story makes it precisely clear what the pilot must do with the stowaway on his ship. The harshness of the situation is made clear by the narrator, who states:
The stowaway had signed his own death warrant when he concealed himself on the ship; he could not be permitted to take seven others with him.
The cold and precise equations of space travel mean that there is no other option but to jettison the stowaway. Yet what crucially changes the picture is the way in which this stowaway is shown to be a young girl who is completely ignorant of the seriousness of her predicament. This makes both us and the pilot begin to hope against hope that there might be someway in which the life of this girl can be saved and not ended so cruelly. This is the biggest question that keeps us turning the pages as we want there to be a way out.
"The Cold Equations" is a suspenseful story because the author presents the reader with a series of questions. First, the reader wonders who the stowaway is on the Emergency Dispatch Ship, or EDS. The pilot picks up the body heat emanating from the supply closet on his gauge, and he then discovers a teenage girl hiding in the closet. Then, the reader wonders why the stowaway climbed aboard the EDS until she explains that she wanted to see her brother. The pilot wonders if she has some ulterior motive for climbing on the EDS, which is trying to deliver serum to help a crew stranded on Woden that has been afflicted with fever. Soon, it's clear that the girl has no ulterior motives, and the reader feels the suspense of wondering what the pilot will do to her. She adds weight to the ship, which will cause it to crash before landing on Woden, so in the end, the pilot must expel his stowaway into space. However, the pilot decelerates the EDS long enough for his passenger to call and write to her brother. The reader wonders until the end of the story if the pilot will kill his passenger, which he ultimately does.