This paper presents a description of the Hubble Space Telescope (HST) Near Infrared Camera and Multi Object Spectrometer (NICMOS) Cooling System (NCS), the cutting edge technology involved, a comparison of predicted versus on-orbit thermal performance, as well as possible future space applications. The NCS hardware consists of the NICMOS Cryogenic Cooler (NCC), an Electronics Support Module (ESM), a Capillary Pumped Loop (CPL)/Radiator assembly, and associated interface harnessing. The NCC is a state-of-the-art reverse Turbo-Brayton cycle mechanical cooler employing micro turbo machinery, driven by advanced power conversion electronics, operating at speeds up to 450,000 revolutions per minute to remove heat from the NICMOS instrument. The ESM provides command, control, and power distribution to the NCS, as well as providing the primary interface to the existing HST electronics. A two-phase CPL system removes heat from the NCC and transfers it to the radiator mounted externally on the HST aft shroud. The system was installed during Servicing Mission 3B via extravehicular activities in March 2002. The NCS revived the NICMOS instrument, which experienced a reduced operational lifetime due to an internal thermal short in its dewar structure, and restored HST scientific infrared capability to operational status.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.