Sheffield's work reminds me of the hard-science multi-plot future history works of the writers of the 50s and early 60s. The work has very much the feel of a serialized sci fi mag piece from Astounding or some such. The usual ingredients are there--a collection of disparate characters enmeshed in a handful of subplots, the mildly dystopian but recognizable earth of fifty years hence, a global threat, eccentric yet capable minds that work to solve it, and, finally, not one but two little puzzle mysteries, with punch line endings to both inquiries. Sheffield's plotting is a real strength; the characterization is a bit pat. I recommend this one, though, as the central dilemma is compelling, and the book lacks the gratuitious glandular or violent juvenalia which infects so many more modern sci fis. This is a fun afternoon, rather than an epic voyage, but not every unmanned satellite can discover a new universe....