The song opens with a six-second audio sample from Jan. 28, 1986, of now-retired NASA public affairs officer Steve Nesbitt saying, "Flight controllers here looking very carefully at the situation. Obviously a major malfunction."
Under fire from friends and family of the astronauts for supposedly making light of the disaster, the pop star, 32, tells ABC News that the sample is actually meant to be a tribute to the dead.
"My heart goes out to the families of those lost in the Challenger disaster," she says in a statement. "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."
She adds, "The songwriters included the audio in tribute to the unselfish work of the Challenger crew with hope that they will never be forgotten."
Among those who feel the sample is insensitive is June Scobee Rodgers, the widow of Challenger commander Dick Scobee.
"We were disappointed to learn that an audio clip from the day we lost our heroic Challenger crew was used in the song 'XO,' " she said in a statement to Central Florida News 13. "The moment included in this song is an emotionally difficult one for the Challenger families, colleagues and friends. We have always chosen to focus not on how our loved ones were lost, but rather on how they lived and how their legacy lives on today."
NASA also released a statement saying no one should make light of the disaster, but without mentioning Beyoncé by name.
"The Challenger accident is an important part of our history; a tragic reminder that space exploration is risky and should never be trivialized," the statement read. "NASA works every day to honor the legacy of our fallen astronauts as we carry out our mission to reach for new heights and explore the universe."
The Space Shuttle Challenger exploded 73 seconds after takeoff from Cape Canaveral, instantly killing all seven crew members on board, including 37-year-old teacher Christa McAuliffe.