The Analog System for the Gamma Ray Spectrometer on Mars Odyssey

摘要

The Gamma Ray Spectrometer instrument on board the Mars Odyssey spacecraft was powered up for the second time since launch in April 2001. High voltage was applied to the Ge detector in February 2002. The system is performing well, but the detector is showing resolution degradation from solar particles and cosmic ray exposure during the long cruise. The analog system and high voltage part of the system were designed and built at NASA's Goddard Space Flight Center. This portion of the instrument system will be presented. Of the many design challenges, three stand out on this mission. The prohibited materials and elemental mass budget for everything used in the construction was defined and constrained. This type of constraint was unique and challenging. Signal overload recovery from cosmic ray and high-energy solar proton hits was a challenge because the environment could not be well defined and varies throughout the Sun cycle. The design effort to prevent microphonic problems in the very sensitive front-end electronics was a challenge because the building of the instrument preceded the spacecraft. The mechanical noise environment from reaction wheels and other mechanisms on the yet to be built and tested spacecraft was based on judgement and analysis. The analog system design and performance data will be discussed.