In this short science-fiction story

In this short science-fiction story, the main protagonist Marilyn is a good person. All she wants is to see her brother and to be assured that he is alive. Therefore, she went on board of a medicine ship, although she knew that it was against laws. However, the ship that can not hold anymore weight. In an exceptional situation when captain wants to live the ship in order to deliver the medicine to the planet, then he has to get rid of Marilyn. In the end, she is jettisoned into the space. The story in general shows the sacrifice of the lead character for the good deed.