Russian Progress M-15M cargo spacecraft undocked early on Tuesday from the International Space Station (ISS) to depart on a three-week scientific mission before being buried in the Pacific.

"The undocking was carried out at 01.16 Moscow time [21:16 GMT on Monday]," Russia's Mission Control said. "The spacecraft will conduct a series of scientific experiments under the Radar-Progress project."

The project focuses on the study of space engines impact on the ionosphere.

"After the project is completed the space freighter will be deorbited and sunk in the Pacific," the Mission Control said.

Progress M-15M arrived at the ISS in April. The freighter undocked from the ISS on July 23 to test an upgraded Russian automated rendezvous system.

The first attempt to re-dock with the ISS using the Kurs-NA system resulted in failure. The spacecraft, however, successfully docked with the orbital station on a second attempt on July 29 after Russian engineers had reprogrammed on-board controls.

Russia is planning to launch its next space freighter, the Progress M-16M, from the Baikonur space center in Kazakhstan on August 1.

The unmanned spacecraft will deliver some 2 metric tons of food, water and fuel supplies to the ISS.