Operating SIRTF for maximum lifetime

The instruments of the Space Infrared Telescope Facility (SIRTF) are cooled directly by liquid helium, while the optical system is cooled by helium vapor. The greater the power dissipation into the liquid helium, the more vapor is produced, and the colder the telescope. Observations at shorter wavelengths do not require telescope temperatures as low as those required at shorter wavelengths. By taking advantage of this, it may be possible to extend the helium and mission lifetime by 10% or even 20%

Operating SIRTF for maximum lifetime

The instruments of the Space Infrared Telescope Facility (SIRTF) are cooled directly by liquid helium, while the optical system is cooled by helium vapor. The greater the power dissipation into the liquid helium, the more vapor is produced, and the colder the telescope. Observations at shorter wavelengths do not require telescope temperatures as low as those required at shorter wavelengths. By taking advantage of this, it may be possible to extend the helium and mission lifetime by 10% or even 20%

Sige Technology For Military And Deep Space Cryogenic Power Electronics

The increasing complexity of power electronic systems needed for advanced deep space missions and military electric-powered systems requires a new approach in materials and processes to realize circuitry and devices that operate efficiently at cryogenic temperatures. The n-type metal oxide semiconductor field effect transistor (n-MOSFET) is the building block for both digital and analog circuits. Silicon (Si) is a good material for fabricating power MOSFETs and electronic devices for operation down to 77 K, below which Si suffers from carrier freeze-out. Silicon carbide (SiC) is a wide-bandgap semiconductor material that is emerging in power electronic applications due to its superior properties, but SiC exhibits carrier freeze-out at temperatures higher than that of Si. Silicon gemanium (SiGe) heterostructure bipolar transistor (HBT) devices are promising candidates for low-temperature power applications. Presently, there is significant uncertainty in SiGe HBT characteristics at cryogenic operating conditions. Technology Applications, Inc. (TAI) has developed and evaluated SiGe strained-gate technology in the power metal oxide semiconductor field effect transistor (MOSFET) and complementary metal oxide semiconductor field effect transistor (CMOSFET) as active and logic devices to be operated in the range of 300 K to 40 K. © 2006 American Institute of Physics