I guess Justin Jacobson (from Blue Devil Games) will be here to give some advice as soon as he spots this thread.
Personally, I think you could certainly enjoy Helios Rising without reading Operation Quick Launch first... but you'd be missing on few things. While HR has a "quick recap" of OQL at the beginning of the book, it's very sparse, and you'll be a bit lost when certain events, alien races and individuals described in OQL are mentioned further in the text (things like: "here's a plot idea for this planet. Let's suppose the players are working for Maximillian Dagos and have to race with a group of the Eos Freedom League for the possession of such and such artifact..." will make you wonder who all these people are supposed to be).
So, yeah, you *can* go ahead with HR without any previous Dawning Star experience if you want (specially if you just want to mine the book for ideas -- there's a *lot* to mine in there!), but you should keep in mind from time to time you'll come up with unexplained bits of information. Not many (compared to what actually is in there), but there you go.
One way to mitigate this, by the way, would be to read as many reviews of OQL as you can beforehand (there are quite a few in RPGnet and maybe here in ENworld too -- some of them linked from
the game's homepage). That way you'll have a head start when the book starts mentioning things like the war between the galactic federation and the vaasi, for example. Besides, it might convince you to buy OQL too.