Florida. The mission of four astronauts to the Moon under NASA's ambitious 'Artemis-II' program has become uncertain again following the emergence of a technical problem. NASA has canceled the planned launch in March after a problem was detected in the helium gas flow in the upper part of the rocket.To resolve this issue, the massive SLS rocket must be removed from the launch site and returned to the Vehicle Assembly Building for repairs. Just last week, NASA officials expressed confidence in a March 6 launch after resolving a hydrogen fuel leak issue.However, the new helium problem observed after the wet...