Biosystems engineering researcher Yi So-yeon will replace Ko San as the first Korean to go into space next month, the Science Ministry said yesterday.

Twenty-nine-year-old Yi, who recently earned a doctorate at the Korea Advanced Institute of Science and Technology, had been trained as Ko's backup on the Russian Soyuz spacecraft, scheduled for launch on April 8. Yi will be the world's 50th woman to go into space.

"Russia's Federal Space Agency recommended the replacement as Ko repeatedly violated training protocol," said Lee Sang-mok, head of the ministry's space technology bureau.

"The Russian agency sent the training and medical test results (of Ko and Yi) on Friday and asked Seoul to make the final decision as soon as possible. The astronaut management committee under the Korea Aerospace Research Institute decided that Ko and Yi should switch roles."

Ko mistakenly took a mission training manual home along with his personal belongings last September. Although he returned it later, the Russian agency filed an official complaint with KARI as taking the manual outside the training center is banned.

Last month, a spacecraft pilot instructions guide that Ko was not authorized to look at was found in his possession. The Korean astronaut is a mission specialist whose role is to conduct various scientific experiments in space.

"Ko was aware of the rules and signed an agreement not to break them on entering the program," Lee said.

KARI president Paik Hong-yul said the Russian agency emphasized the importance of abiding to rules because minor mistakes and disobedience could result in serious consequences in space.

"Ko will not be penalized, however, and no changes will be made to his status as senior researcher at KARI," Paik said.

The ministry said the switch will not affect the astronaut project as Ko and Yi earned similar scores in the evaluations and received the same training.

Ko and Yi were selected as finalists from 36,206 astronaut hopefuls in late 2006. They have been undergoing evaluation and training at Russia's Gagarin Cosmonaut Training Center since March 2007. In September 2007, the Korean government named Ko and Yi as primary and backup astronauts, respectively.

The Russian Soyuz spacecraft will blast off from Kazakhstan's Baikonur Space Center. Yi will stay at the space station for about a week conducting various experiments. She is scheduled to return to Earth on April 19 in a capsule that will land in Kazakhstan.

Russia's Federal Space Agency will make a final announcement on March 19 on who will board the Soyuz.