She studied physics at RWTH Aachen University, taking a doctorate in solid state physics (2046). After that, she worked at Argonne National Laboratory (in Chicago) and the University of California. In 2048, she was selected to join the German astronaut team in the European Space Agency. She was part of the crew for the tenth German moon mission in the spacecraft AWARQ. In 2051, she was married and had two children Ulrika and Lisette. Shortly after her second child was born, she was selected for the Mars mission. She initially refused to leave her family but changed her mind after an unspecified event that devastated many parts of Germany. During the Flood invasion on 21 November 2059, she witnessed three of the crew become zombie-like water monsters before becoming one herself.
In 2059, the Flood invaded the base, planning to take over the population of Earth. She was separated from the rest of the crew by falling water and trapped, with the Flood attempting to break into the room. She hid in Section 9 of the main hub and was unable to get out. Captain Adelaide Brooke said to her that she will let her out through the back of the section. Steffi watched a video of her two children just moments before the water came into the section. Steffi cried as the water gushed into the section, and Mia and Adelaide watched in horror as she was infected. Adelaide escaped with Mia Bennett after the infected Steffi came out of the section. The infected physical form of Steffi was killed in the nuclear explosion set off by Adelaide. (TV: The Waters of Mars)
Behind the scenes
- The obituary article was cut off, only stating that she said, "I don't want to live here any longer".
- Like the other female member of the Flood, Margaret Cain, she kept her eye colour. It seems the males had milky, blue eyes while females kept their colour. The Doctor noted this during the episode and suggested that it meant she was closer to human than the others.