Beyonce has defended her decision to include audio commentary from the Space Shuttle Challenger disaster in a new song. The singer's track XO, about a doomed relationship, features a snippet of NASA public affairs officer Steve Nesbitt talking about the 1986 tragedy, when the shuttle broke apart shortly after its launch, killing all seven crew members. In the six-second clip, Nesbitt is heard saying, "Flight controllers here looking very carefully at the situation. Obviously a major malfunction." Beyonce has since come under fire for including the emotionally-charged audio in the pop song. June Scobee Rodgers, widow of Challenger's Commander Dick Scobee, criticised the singer, saying, "We were disappointed to learn that an audio clip from the day we lost our heroic Challenger crew was used in the song XO. The moment included in this song is an emotionally difficult one for the Challenger families, colleagues and friends." Retired NASA astronaut Clayton Anderson says, "For the words to be used in the video is simply insensitive, at the very least", while another former NASA employee, Keith Cowing, brands the inclusion "inappropriate in the extreme". The singer has now faced down calls for an apology by releasing a statement defending her decision to use the clip. The statement, obtained by America's ABC News, reads, "My heart goes out to the families of those lost in the Challenger disaster. The song XO was recorded with the sincerest intention to help heal those who have lost loved ones and to remind us that unexpected things happen, so love and appreciate every minute that you have with those who mean the most to you. "The songwriters included the audio in tribute to the unselfish work of the Challenger crew with hope that they will never be forgotten."