Two books from the same series Exploring Space, The Hubble Telescope and NASA are level 3  of their 5 level scale and follow similar formats.  One or two sentences per page with large font; full color photos are used throughout and most span both pages.  Because of the science background, the vocabulary is more pretty complex for the type of audience it is written.  Pronunciation guides would have been helpful.  Simple research at an elementary level or upper grade ELL students might find these books useful.  Additional selection for most libraries.