Terrasphere 8, Starfleet Command Re-creation, was one of about a dozen environmental domes built by Species 8472 throughout the Delta Quadrant to train its people for eventual infiltration of Earth and the Federation. The facility contained an elaborate simulation of the Starfleet Command complex in San Francisco, Earth, and was occupied by the fluidic-space lifeforms isomorphically altered to live as humanoids. The 8472 plan was to familiarize themselves with the procedures, traditions and values of Federation society, and then to place operatives in the highest levels of Starfleet to conduct reconnaissance and to monitor military installations.
Powered by 13 thermionic generators, the simulation used a combination of holographic projection and particle synthesis. The re-creation included not only much of Starfleet Headquarters, but part of the surrounding city of San Francisco, including the Quantum Cafe (although the simulation did not extend to Market Street). The lifeforms posed as actual Federation personnel, including Admiral Bullock, Commander Valerie Archer, Lt. Kinis and groundskeeper Boothby. It was never determined exactly how the species gathered its intelligence.
These training exercises started in 2374 shortly after the U.S.S. Voyager's first encounter with the fluidic-space beings, and continued for about a year until peace overtures from Captain Janeway — in the form of technological exchanges — compelled them to cease their activities and return to their realm.