She has lived a long time and changes her name and job every decade or so to stop getting bored. She chose the name Calamity because she thought it was nice. Although she has never tried a job in science before, she found she was really quite good at it, "according to Doctor Henry."
If Keene and the other 3-4 nightkin go hostile during the quest Guess Who I Saw Today, it's possible Calamity will get caught in the crossfire and die. Try to dispatch the nightkin quickly if you wish to avoid this.
It is possible that she is named after frontierswoman Calamity Jane.