Heat Shields RL-10 propellant ducts must prevent heating to the propellant. Hydrazine thrusters for propellant settling and attitude control. Large plume (in space). To minimize heat from hydrazine, corrugated metal mounted on engine act as standoff for heat from (~the plume ? in notes) Heating occurs during coasting phase. Coast 10 min - 5 1/2 hours (for GEO). Solar radiation heats craft if the sun faces the back end of the vehicle. To keep pumps cooler - radiation blankets. Bottles and lines have heat shields. Standoff shields to shield from cryogenic leak. Keep minor problems from becomming catastrophic, e.g., fitting springs a small leak. H2 system lines are protected from cryogenic leaks. Centaur - H2O2 originally. Designer wanted to use hydrazine. ~??