From C. Leroy Ellenberger
The report on Erik Bollt and James Meiss’s low-energy trajectory from Earth to Moon (New Scientist, Science, 7 October) is incorrect in reporting, “Until now the trajectory considered the most economical was the Hohmann transfer orbit.” In 1991, Edward Belbruno and James Miller at the Jet Propulsion Laboratory worked out a low-energy trajectory that enabled the disabled Japanese spacecraft Hiten to reach the Moon in five months versus the usual three-day Hohmann route. Their trajectory saved about 25 per cent of the fuel needed for a Hohmann transfer.
Since the Bollt and Meiss two-year route to the Moon saves about 50 per cent over a Hohmann transfer, it produces a 33 per cent saving over the Belbruno and Miller route.
