Challenger
Word family (noun) challenge challenger (adjective) challenging challenged ≠ unchallenged unchallengeable (verb) challenge (adverb) challengingly
From Longman Dictionary of Contemporary EnglishChallengerChal‧len‧ger /ˈtʃæləndʒə $ -dʒər/ a US spaceshuttle which exploded after takeoff on one of its flights in 1986, killing all seven people inside. The terrible accident was watched on television by many people and shocked the whole of the US.