It’s pretty rare that we get two magnificent new launch vehicles getting their first flight within a week of each other, but that’s what happened with the LADEE/Minotaur V launch on Sept. 7th and the SPRINT-A/Epsilon launch on Sept. 14th. Both rockets use a series of solid stages to boost their payload – the Minotaur V puts 630 kg into geosynchronous transfer orbit or, in the case of LADEE, 437 kg into trans-lunar trajectory, while the Epsilon puts 1200 kg into low Earth orbit.
The benefit to solid stages are that they are cheap and relatively non-volatile (unlike cryogenic fuels). As you’ll see in the videos, they also get going rather quickly (that is, they have a very high thrust-to-weight ratio). The downside is that they are relatively inefficient in terms of ISP, and so aren’t suited to heavy loads in the upper atmosphere/space. They are also not throttled and lack the safety features of liquid rockets, so they aren’t used for manned flights.
Without further ado, there are the spectacular videos of the launches: