the boom mic is situated within the expanding area of atmosphere expelled from the exploding objects
Poor mic
Basically, if you understand physics to at least some extent, where the explosion could be heard in mostly vacuum (some atoms here and there don't count) would be the last place you wanna be. You can "hear" only what propagates as (a shock-wave) vibrations of matter... in this case, the only matter carrying that "info" would be the same that just exploded... so, you'll need to be within the blast area to hear an explosion in space. That's something I'd try to avoid if possible
Don't forget there's absolutely nothing decelerating this exploding matter in vacuum so anything hitting you that would in turn produce "sound" it'd have way too much power for comfort (whatever its mass)
Also, the way mics work, they wouldn't record that "nice" cabooooom... more likely a short squeak of its membrane tearing apart.
EDIT: Just remembered... there's also no sound barrier in vacuum (less the one that's within the matter exploding), so if we were able to record the sound of an explosion in it, it'd prolly produce high pitched "Geiger counter" like sound... prolly similar to what you hear if you "tune in" to Jupiter with your FM receiver. Also, you wouldn't hear a thing until that blast reaches you. I'd most definitely smell my own soiled panties first