Updating Chandra high-radiation safing in response to changing observatory conditions

Michael Juda; Mark Baski; Chris Eagan; Jeff Holmes; Sabina Hurley; David Jones; Eric Martin; Harold Rice; Paul Viens; Brent Williams; Daniel Wong

doi:10.1117/12.940772

13 September 2012 Updating Chandra high-radiation safing in response to changing observatory conditions

Michael Juda, Mark Baski, Chris Eagan, Jeff Holmes, Sabina Hurley, David Jones, Eric Martin, Harold Rice, Paul Viens, Brent Williams, Daniel Wong

Author Affiliations +

Proceedings Volume 8448, Observatory Operations: Strategies, Processes, and Systems IV; 844805 (2012) https://doi.org/10.1117/12.940772
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

The science instruments on-board the Chandra X-ray Observatory may be damaged by high fluxes of energetic particles produced in Solar storms. For twelve years the on-board commanding used to safe the instruments when a high-radiation environment was identified included stopping all on-board scheduled activity. Over this time the conditions of the observatory have changed: the orbit has evolved to lower perigee and the thermal protective surfaces have degraded. The likelihood of an unplanned unload of spacecraft angular momentum, a spacecraft component exceeding thermal limits, or an eclipse passage without planned commanding occurring following a Solar storm during the upcoming Solarmaximum due to the lack of scheduled commanding led us to update the Chandra response to a high-radiation environment; commands are sent to safe the science instruments but vehicle related commanding (maneuvers, angularmomentum unloads, eclipse commands) are allowed to continue. While this was a conceptually simple change, it touched all elements of the program, including flight software, the planning and commanding systems, flight-load verification tools, and ground-based data processing. A key to successful and timely implementation was the establishment of a working group with representation from all elements of the program.

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Michael Juda, Mark Baski, Chris Eagan, Jeff Holmes, Sabina Hurley, David Jones, Eric Martin, Harold Rice, Paul Viens, Brent Williams, and Daniel Wong "Updating Chandra high-radiation safing in response to changing observatory conditions", Proc. SPIE 8448, Observatory Operations: Strategies, Processes, and Systems IV, 844805 (13 September 2012); https://doi.org/10.1117/12.940772

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KEYWORDS

Observatories

Space operations

Software development

Silicon

Particles

X-rays

Sun

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