The Soviets were fond of multi-tube rocket launchers in WWII. They called them the Katyusha and the design persists to this day. They didn’t invent it – I believe that honor goes hundreds of years back to the Chinese – but they really turned it into a weapons system. As we see in the Middle East, they have never been able to hit the broad side of a barn, although they might scare half the cows to death anyway.
Why use them at all? They are an incredibly cheap and easily deployed way to get payload down field. Not remotely accurate but again very cheap and your truck driver can, in a pinch, serve as your firing team. “Yes Petrovich, I know the rest of the team is dead, but all you have to do is drive somewhere over there (pointing at map drawn in blood on a table in a bombed out cafe) point tubes up and towards Germany, and push button. Is piece of cake. All of our people over there are probably dead anyway! So what are you worried about! Shoot rockets, come back!”
Basic Soviet battle doctrine can be summed up as “why use 10 when 100 might work better?”. If you put enough explosives into the air then some of them will accidentally kill people you want to kill and destroy things that you want to destroy.
Enter the plucky little GBU-39B, a small bomb that is the antithesis of the Katyusha. It’s relatively small (50ish lb payload) so 6 of them can be carried INSIDE a Joint Strike Fighter. It has wings and a bunch of electronics allowing it to glide down and hit things with pinpoint accuracy. How pinpoint, I hear you ask?
Now engineers at Boeing and SAAB are partnering on what can be described as the smart kid sister of the Katyusha. They are taking the GBU-39B, gluing an existing off0the-shelf rocket motor to its butt and packaging it up so that it can be fired from the M270A1, which is a multi-tube launch vehicle that is already on the ground all over the world. The M270A1 has for the most part been a lot like the Katyusha and has even been nicknamed the GSRS, which stands for Grid Square Removal System because it can cover an entire 1 Km sqaure with grenades (of which several hundred probably won’t explode right away, which is bad).
So what will this new munition do? It will give the M270A1 12 guided bombs that can each be independently precisely targeted (no more hail marys) at ranges of up to 75+ Km. It’s a giant mobile battery firing pinpoint explosives, which among other things is good for civilian populations that aren’t all already dead.
Here’s the Janes take on this new system: http://www.janes.com/article/49876/boeing-teams-with-saab-to-offer-manoeuvrable-sdb-based-artillery