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nasa hopes they ' ll do well today with the launch of the first of a pair of identical rovers headed to the red planet .
 nasa, they, the first of a pair of identical rovers headed to the red planet, a pair of identical rovers headed to the red planet, the red planet
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: organization, person, geographical social political, vehicle, location, weapon, facility 
Text: {0} 
Answer:
 nasa, they, the first of a pair of identical rovers headed to the red planet, a pair of identical rovers headed to the red planet, the red planet