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An atmospheric shuttle ferries a group around Laura Roslin seeking the whereabouts of Earth to the Galleon Meadow on Kobol (Home, Part I), and docks to Galactica in "Act of Contrition". A shuttle is also seen at rest on the surface of New Caprica during its colonization, and during food retrieval efforts on the algae planet (The Eye of Jupiter).
Three distinct shuttle models have been identified. For classification purposes only, as their true specifications are unknown, they are identified on this page as follows: "Heavy" Shuttle, "General Purpose" Shuttle, and Cylon War-era Shuttle.
First seen in the opening scene of the Miniseries, it appears to be a clear homage to the original shuttle seen in TOS. There is little to use to gauge the true size of the craft, but it appears to be larger with it's bulk more fully filled out down the length of the vessel.
This model is definitely FTL capable per the exchange between Commander William Adama and Lt. Felix Gaeta in the Miniseries: "Courier officer's overdue coming back from Armistice Station. They've asked for a full status report on all FTL-capable ships just in case they need somebody to jump out there today....". Clearly a FTL capable vessel was required to reach the Armistice Station.
"General Purpose" Shuttle
This model appears to be the most commonly used, especially in civilian service. But it is also used by the military as well. However it is never clear if this model has FTL capability.
Cylon War-era Shuttle
This model, as best can be determined by the one low resolution shot of it from the Miniseries and Razor Flashbacks, is TOS version of the shuttle. Again, it is not known if this model is FTL capable either.
Gauging by the Mk II Vipers near the shuttle in the image, one can determine a very rough approximation of the shuttle being the equivalent of 2-3 Vipers in length.