I was initially thinking the same thing, but it occurred to me that they engaged it when the sun was shining. The solar IR reflection from the balloon could have been (should have been) a higher signature than the sky background at that altitude, allowing a heat-seeking missile to do the trick. From the video clip I saw (very tedious to watch), it looked like the balloon was just blown out like a candle flame. This would be consistent with a Sidewinder missile penetrating the envelope and detonating its warhead within the balloon. The overpressure would pop the balloon. This hints at performance flexibility with the Sidewinder that isn't advertised.
I had to analyze the flight patterns of a large number of weather balloons in order to assess them as a target option for the YAL-1A. We never got around to using it. I developed a fairly successful model for the ascent dynamics of the balloons, from first principles.
I was initially thinking the same thing, but it occurred to me that they engaged it when the sun was shining. The solar IR reflection from the balloon could have been (should have been) a higher signature than the sky background at that altitude, allowing a heat-seeking missile to do the trick. From the video clip I saw (very tedious to watch), it looked like the balloon was just blown out like a candle flame. This would be consistent with a Sidewinder missile penetrating the envelope and detonating its warhead within the balloon. The overpressure would pop the balloon. This hints at performance flexibility with the Sidewinder that isn't advertised.
I had to analyze the flight patterns of a large number of weather balloons in order to assess them as a target option for the YAL-1A. We never got around to using it. I developed a fairly successful model for the ascent dynamics of the balloons, from first principles.