File:Moon Farside LRO.jpg

English: Far side of the moon, by NASA's Lunar Reconnaisance Orbiter. Orthographic projection centred at 180° longitude, 0° latitude.

Because the moon is tidally locked (meaning the same side always faces Earth), it was not until 1959 that the far side was first imaged by the Soviet Luna 3 spacecraft (hence the Russian names for prominent far side features, such as Mare Moscoviense). Unlike the widespread maria on the near side, basaltic volcanism was restricted to a relatively few, smaller regions on the far side, and the battered highlands crust dominated. A different world from what we saw from Earth.
Of course, the cause of the far side/near side asymmetry is an interesting scientific question. Past studies have shown that the crust on the far side is thicker, likely making it more difficult for magmas to erupt on the surface, limiting the amount of far side mare basalts. Why is the far side crust thicker? That is still open to debate, and in fact several presentations at this week's Lunar and Planetary Science Conference attempt to answer this question.
The Clementine mission obtained beautiful mosaics with the sun high in the sky (low phase angles), but did not have the opportunity to observe the far side at sun angles favourable for seeing surface topography. This Wide Angle Camera (WAC) mosaic provides the most complete look at the morphology of the far side to date, and will provide a valuable resource for the scientific community.
The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) is a push-frame camera that captures seven colour bands (321, 360, 415, 566, 604, 643, and 689 nm) with a 57-km swath (105-km swath in monochrome mode) from a 50 km orbit. One of the primary objectives of LROC is to provide a global 100 m/pixel monochrome (643 nm) base map with incidence angles between 55°-70° at the equator, lighting that is favourable for morphological interpretations. Each month, the WAC provides nearly complete coverage of the moon under unique lighting. As an added bonus, the orbit-to-orbit image overlap provides stereo coverage. Reducing all these stereo images into a global topographic map is a big job, and is being led by LROC Team Members from the German Aerospace Centre (Deutsches Zentrum für Luft- und Raumfahrt; DLR). Several preliminary WAC topographic products have appeared in LROC featured images over the past year (Orientale basin, Sinus Iridum). The WAC topographic dataset will be completed and released later this year.

The global mosaic released today is comprised of over 15,000 WAC images acquired between November 2009 and February 2011. The non-polar images were map projected onto the GLD100 shape model (WAC derived 100 m/pixel DTM), while polar images were map projected on the LOLA shape model. In addition, the LOLA derived crossover corrected ephemeris, and an improved camera pointing, provide accurate positioning (better than 100 m) of each WAC image.