"Sunjammer" is a science fiction short story by British writer Arthur C. Clarke, originally published in the March 1964 issue of Boys' Life.
The sun-yachts start their journey in Earth's orbit, and, pushed simply by sunlight, can achieve a speed of two thousand miles an hour within a day.
His hopes for victory rest on the low mass of his craft which he has made possible through advances in automation enabling him to fly it solo.
Although the Lebedev is lagging Merton's yacht, its senior pilot delivers a surprise blow by announcing that he plans to jettison his co-pilot in an escape capsule now that the earlier, navigationally intensive part of the race has finished.
Merton responds by recalculating his expected margin of victory and realises that the race is now going to be neck-and-neck at the finish line.