|COBE Engineering Information
from the Cryogenics & Fluids Branch
NASA Goddard Space Flight Center.
Steve Castles, Mike Ryschkewitsch, Steve Volz, Michael DiPirro
The COBE dewar was a 660 liter liquid helium cryostat. It provided a stable 1.4 Kelvin environment for the two cold instruments, the Far Infrared Absolute Spectrophotometer (FIRAS) and the Diffuse Infrared Background Experiment (DIRBE).
The first phase of the COBE science mission came to an end on Friday, September 21, 1990, after 306 days of cryogenic operations as the last of the superfluid helium contained within the dewar was consumed. The final depletion of the helium cryogen marked the successful end of scientific operations for one of the three COBE instruments, FIRAS, and for a portion of a second instrument, DIRBE. DIRBE continued to make useful and accurate observations in the near infrared bands for three more years, along with the Differential Microwave Radiometer (DMR).
The long on orbit operating time enabled the FIRAS and DIRBE to completely map the sky, dramatically increasing the sensitivity and detail of the cosmic background radiation measurements. The dewar was developed by Ball Corporation and managed by Code 713 (now Code 552).