NSSDCA ID: 2005-025A-01
Mission Name: SuzakuThe Suzaku XRS(covering the 0.3 - 12 keV range) was the first X-ray microcalorimeter flown on an orbiting observatory, and the acknowledged "primary" instrument on Suzaku. It was a non-dispersive (thus, high-efficiency) imaging (30-element) spectrometer (about 6.5 eV FWHM). It was cryogenically cooled by an adiabatic diamagnetic refrigerator within a helium dewar, which, as well as the XRS sensor, was provided by GSFC. The helium dewar is located within a Japanese-provided solid neon dewar, which in turn is cooled by a mechanical cooler. The detector array sits behind a conical foil mirror (X-ray Telescope, or XRT) assembly provided by the GSFC, with spatial resolution of about 1.8' half power diameter (HPD). The effective area of this system at 6 keV is about 150 cm2.
After a successful launch of Suzaku (Astro-E2) on July 10, 2005 the X-ray Spectrometer (XRS) was activated and performed to specifications for almost three weeks. An anomaly appeared on July 29, 2005, three days after the dewar main shell vent valve was opened. Several abrupt temperature changes were observed in parts of the dewar and other signatures that were clear signs of a momentary puff of helium gas in the dewar vacuum space. All of the temperatures recovered very quickly after the event as the gas rapidly adsorbed onto the cold surfaces of the helium cryostat and the detector system, but the event substantially degraded the spectral resolution of the array. Heating the detector system to greater than 6 K effectively degassed the array and recovered the original 7 eV resolution performance. More events were seen over the following days, with the frequency increasing. Degassing again recovered the original spectral resolution. On August 8, 2005, there were two more of these events, the second of which overwhelmed the dewar vacuum, caused a thermal short between the helium and neon tanks, and resulted in the liquid helium boiling off and completely venting to space.
Without the helium cryogen, the XRS instrument could no longer provide the planned science.
Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office
Name | Role | Original Affiliation | |
---|---|---|---|
Dr. Richard L. Kelley | Principal Investigator | NASA Goddard Space Flight Center | kelley@lheavx.gsfc.nasa.gov |