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Thanks for sharing your anecdote! In fact, ISRO's Moon mission Chandrayaan-1 ended prematurely due to overheating of star sensor and power supply unit (inadequ

by swatkat 13y ago

Thanks for sharing your anecdote! In fact, ISRO's Moon mission Chandrayaan-1 ended prematurely due to overheating of star sensor and power supply unit (inadequate thermal protection!). They underestimated the amount of radiation from the Sun and that reflected by the Moon, at an orbit of 100km from the Moon[1]. For MOM, ISRO has "hardened" their satellite bus with better thermal protection, larger solar panels, redundant subsystems, redundant fuel lines, FDIR system etc.[2] Hoping for the best :) [1]http://www.brighthub.com/science/space/articles/48921.aspx http://www.brighthub.com/science/space/articles/48921.aspx [2]http://www.isro.gov.in/pslv-c25/pdf/pslv-c25-brochure.pdf http://www.isro.gov.in/pslv-c25/pdf/pslv-c25-brochure.pdf ("Major Challenges" section)

DougWebb 13y ago
Cool. Another of my jobs at GE AstroSpace involved writing software to help with the analysis of thermal system modeling. At its heart, thermal modeling is basically the same as one of the approaches for lighting models for 3D graphics: every surface within the spacecraft is radiating and absorbing heat from every other surface that it faces. This is similar to the way every surface in a 3D model visualization is emitting, reflecting, and absorbing various frequencies of light from every other surface it faces in the model. The math is the same, but in the thermal model you're calculating an equilibrium state to figure out the final temperature of each surface, or cyclic variation in the case of a rotating spacecraft with the sun and other emitting bodies around it. That tells you if temperatures are within the tolerance range of the components over the mission lifetime. If not, you have to add thermal protection and rerun the simulation. This probably all goes a lot faster today than it did on the 1990's era VAX minicomputer I was using. There's probably real-time visualization now, which I'll bet is pretty cool.

by swatkat 13y ago

DougWebb 13y ago

Cool. Another of my jobs at GE AstroSpace involved writing software to help with the analysis of thermal system modeling. At its heart, thermal modeling is basically the same as one of the approaches for lighting models for 3D graphics: every surface within the spacecraft is radiating and absorbing heat from every other surface that it faces. This is similar to the way every surface in a 3D model visualization is emitting, reflecting, and absorbing various frequencies of light from every other surface it faces in the model. The math is the same, but in the thermal model you're calculating an equilibrium state to figure out the final temperature of each surface, or cyclic variation in the case of a rotating spacecraft with the sun and other emitting bodies around it. That tells you if temperatures are within the tolerance range of the components over the mission lifetime. If not, you have to add thermal protection and rerun the simulation. This probably all goes a lot faster today than it did on the 1990's era VAX minicomputer I was using. There's probably real-time visualization now, which I'll bet is pretty cool.