60336
Once the prime mission concluded , an extended mission started on December 7 , 1997 ; the spacecraft made several flybys of Europa and Io .
 Europa, Io
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:
 Europa, Io