earlier instruments. NICMOS in turn has been largely superseded by the Wide Field Camera 3, which has a much larger field of view (135 by 127 arcsec, or 2.3 by 2.1 arcminutes), and reaches almost as far into the infrared. When conducting infrared measurements, it is necessary to keep the infrared detectors cooled to avoid having infrared interference from the instrument's own thermal emissions. NICMOS contains a cryogenic dewar, that cooled its detectors to about 61 K, and optical filters to ~ 105 K, with a block of solid nitrogen ice. When NICMOS was installed in 1997, the dewar flask contained a 230-pound (104 kg) block of nitrogen ice. Due to a thermal short that arose on March 4, 1997, during the instrument commissioning, the dewar ran out of nitrogen coolant sooner than expected in January 1999. During Hubble Service Mission 3B in 2002 (STS-109), a replacement cooling system comprising a cryocooler, cryogenic circulator, and external radiator was installed on the Hubble that now cools NICMOS through a cryogenic neon loop. The NICMOS Cooling System (NCS) was developed on a very accelerated schedule (14 months vs. 5–10 years for other Hubble instrument hardware). NICMOS was returned to service soon after SM 3B. A new software upload in September 2008 necessitated a brief shutdown of the NICMOS cooling system. Several attempts to restart the cooling system were unsuccessful due to issues with the cryogenic circulator. After waiting more than six weeks for parts of the instrument to warm up, and theorized ice particles to sublimate from the neon circulating loop, the cooler once again failed to restart. An Anomaly Review Board (ARB) was then convened by NASA. The ARB concluded that ice or other solid particle migrated from the dewar to the circulator during the September 2008 restart attempt and that the circulator may be damaged, and determined an alternative set of startup parameters. A successful restart at 13:30 EST on 16 December 2008 led to four days of cooler operations followed by another shutdown. On 1 August 2009, the cooler was restarted again; NICMOS was expected to resume operations in mid-February 2010 and operated through October 22, 2009, at which point a lock-up of Hubble's data handling system caused the telescope to shut down. The circulation flow rate to NICMOS was greatly reduced during this operating period confirming blockage in the circulation loop. Continued operation at reduced flow rates would