Sakigake—translating to "pioneer" or "", known before launch as
MS-T5—was
Japan's first
interplanetary spacecraft, and the first deep space probe to be launched by any country other than the USA or the Soviet Union. It aimed to demonstrate the performance of the new launch vehicle, test the schemes of the first escape from the
Earth gravitation for
Japan on
engineering basis, and observe space
plasma and
magnetic field in interplanetary
space. Sakigake was also supposed to get references for scientists. Early measurements would be used to improve the mission of the
Suisei probe several months later.