A Russian rocket has successfully launched an unmanned cargo ship to the International Space Station, whose crew is anxiously awaiting it after the successive failures of two previous supply missions.

A Soyuz-U rocket blasted off as scheduled from Russia-leased Baikonur launch pad in Kazakhstan, placing the Progress M-28M cargo ship into a designated orbit.

The previous Progress launch in April ended in failure, and on Sunday a U.S. supply mission failed too when SpaceX's Falcon 9 rocket broke apart shortly after liftoff. The success of Friday's launch is essential for the station program, which has relied on Russian spacecraft for ferrying crews after the grounding of the U.S. shuttle fleet.

The next station crew's launch has been pushed back from late May to late July after April's failure.