Although the Science Facility does not directly build any units, they enable the production of the Science Vessel at Starports. The Science Facility has three research upgrades for the Science Vessel: EMP Shockwave, Irradiate, and Titan Reactor (+50 Energy).
One of two add-ons can be constructed onto the Science Facility, the Covert Ops and Physics Lab, which unlock production of the Ghost and Battlecruiser, respectively. These add-ons also allow and research upgrades for each of the two units.
Lifting off the Science Facility will render any add-on that was attached to be ineffective. Furthermore, when lifted off, the Science Facility cannot execute any research upgrades. Nonetheless, because Ghosts and Battlecruisers are not common during professional play, the add-ons are usually not constructed. Rather, the Terran player will often leave the Science Facility lifted off to use its footprint as construction space for other buildings. In fact, many Terran players choose to fly the lifted off Science Facility to the edges of their bases to expand their vision.