Mission Summary
Japan's highly experimental entry into deep-space exploration. It's goals were to test advanced spacecraft navigation techniques, including lunar flybys, gravity assists, aerobraking, and low-energy routes to the Moon. It helped establish Japan’s capability for future lunar and deep-space exploration.
The primary mission architecture relied on a tandem payload configuration. During its very first close flyby of the Moon, Hiten successfully deployed Hagoromo, a tiny 26-pound (12 kg) companion orbiter meant to enter a permanent lunar orbit. However, Hagoromo's radio transmitter failed immediately, leaving ground control with no tracking data to verify if the mini-satellite actually achieved orbit.
A brilliant piece of navigation saved the program from failure. Because Hiten did not carry enough heavy fuel to brake itself directly into a standard lunar orbit, ground teams had to get creative. Working with an American mathematician, they calculated a completely new pathway that used the natural gravity of the Sun and Earth to slowly pull the spacecraft toward its destination with almost zero fuel consumption. This clever gamble succeeded perfectly, allowing Hiten to glide smoothly into orbit around the Moon in February 1992 before finally completing its journey with a planned crash into the lunar surface on April 10, 1993.
Sources and notes can be found on the Sources page.
