The H-2A rocket lifted off Thursday morning from Tanegashima Space Center in southwestern Japan.
It carried Michibiki No.2, which is part of a 4-satellite system. The satellite was put into orbit at the scheduled time.
The system's first satellite was sent into space 7 years ago. Two others will be launched later this year. Each will orbit Japan for 8 hours a day so that at least one satellite will be flying over the country at all times.