52031
He never contracted the illness , but was nevertheless removed from the crew and replaced by his backup , Jack Swigert , three days before the launch .
 Jack Swigert
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Jack Swigert