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Staring into the glowing blue exhaust of a mercury-ion thruster
February 1980, p. 54-55
James L. Long and Associates (photo)

Swift watched a loading crew top off the tanks of mercury propellant, blow invisible specks of dust off the kilometer-long solar array panels with one pass of a cold-gas teleoperator bus, and then drift away toward the distant, slowly rotating torus that hung above the blue crescent of Earth below.