One of these in particular, Space Science Reviews, is the journal that publishes most of the articles of record that describe spacecraft instruments. As a mission prepares for launch or arrival, there will be a special issue of SSR for that mission that describes the mission in general and each individual instrument in painful detail. Do you have questions about what isotopes Curiosity's SAM can discern or whether it can measure the chirality of amino acids? Want to know the angular resolution and spectral sensitivity of New Horizons' LORRI camera? This is the journal you go to. (Volumes 170 and 140, respectively.)
I have been throwing around the idea of trying to do a seminar-style class were we pick some papers and discuss them over a Hangout. If I do that, though, people will need access to papers. If you have any interest in such a class, go download them now, while they're free. I read the fine print on Springer's website and I don't think it makes a difference whether you got it for free or not; the copy that you download belongs to you; sharing it with others violates copyright. So once they're back behind the paywall, they're back behind the paywall.
We know you love reading about space exploration, but did you know you can make it happen?