Their instruments told them they were nearing perigee again. Jiro, assisted by Dinah, executed what they hoped would be the second-to-last burn of the big engine. This went on longer than Jiro had predicted, but it seemed to work. Ymir shed most of her excess velocity. Her orbit, at apogee, was now only a few hundred kilometers higher than Izzy’s. In spite of attrition suffered by the robots as they wore out, broke, or succumbed to radiation damage, Dinah still had enough of them to restock the hoppers for the final major burn, which they calculated would be happening at a perigee a few hours later.