I think the prayer was over the little boy bomb that dropped on Hiroshima (because the prayer doesn't mention a previous mission), but I forget.
Blessing the crews and their two missions was Fr. George Zabelka, the Catholic chaplain to the 509th Composite Group -- the atomic bomb group.
https://www.dropbox.com/s/65949bloqdj4u8p/Zabelka%E2%80%94The%20Reluctant%20Prophet.mp4?dl=0