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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.

The Advanced Camera for Surveys (ACS) is an instrument containing two charged-coupled device (CCD) cameras and a multi-anode multi-channel array (MAMA) detector being built by Ball Aerospace and Technologies Corporation for NASA's Goddard Space Flight Center. The instrument is scheduled to be installed in the Hubble Space Telescope during a space shuttle mission in December of 1999. The CCD detectors need to operate at a temperature below -80 degrees C in order to avoid unacceptable dark current. This cooling is achieved with thermo-electric coolers (TEC) mounted in evacuated assemblies that contain the detectors. Heat that is generated by the TECs must be dissipated to space. Since the CCd assemblies are centrally located within the instrument enclosure, a method must be provided for transferring this heat to a heat rejection surfaces. Heat pipes have been selected for this purpose since they are frequently used in space applications for passively transferring heat from sources to remotely located radiating panels. The alignment of the CCDs is critical, however, so the loads induced into the detectors and the optical bench containing the sensor assemblies through heat pipes must be minimized. Consequently, the CCD heat pipes have been designed with a flexible section to minimize either thermally generated or launch induced structural loads. Structural and thermal testing has shown that these heat pipes will allow the ACS detectors to attain their operating temperature while meeting alignment stability requirements. This paper presents the design of and test results from the ACS flexible heat pipes.

We describe the engineering design and operational concept for a series of three complementary top mounted balloon- borne experiments to measure the Cosmic Microwave Background Radiation anisotropy, culminating in a two week circumpolar flight from McMurdo Station, Antarctica. Each experiment is designed to provide a maximum science return in addition to acting as a pathfinder to the successor flights of top- mounted balloon-borne experiments. The experiment program, named TopHat, will involve the launch and operation of the first far-infrared and microwave telescope flown entirely from the top of a 28 million cubic foot balloon. It utilizes a two axis gimbal pointing system, a one meter Cassegrain optical system with a chopping secondary mirror, and a 3He evaporation cryostat designed to maintain a bolometer detector temperature of 0.25 K for 30 days without cycling. The series of flights will begin with an engineering test flight scheduled for launch in July 1996 from Palestine, Texas, followed by a pointing experiment to be flown from Ft. Sumner, New Mexico in April 1997. A spinning experiment will be launched from Ft. Sumner in April 1998 and Antarctica in December 1998.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.