A capsule ejected from a space cargo vessel returned to Earth on Sunday, bringing back experiment samples from the International Space Station in the first such mission for Japan.

The Japanese Aerospace Exploration Agency said the capsule, measuring 84 centimeters in width and 66 cm in height, made a parachute-assisted splashdown in the Pacific near Japan's far-east Minamitori Island early in the morning and was retrieved later in the day.

(Kounotori7 departing the International Space Station)[Photo courtesy of JAXA]

"I think we've succeeded almost as planned," Hirohiko Uematsu, technology director of JAXA, told a press conference at its Tsukuba Space Center in Ibaraki Prefecture. "Japan has obtained the technology that is essential for us to move forward."

JAXA is now aiming to develop a new capsule that can return home without being assisted by a space vessel, while the success of the latest mission is also expected to help develop Japan's own spacecraft for manned missions in the future.

The retrieved capsule contains protein crystals grown in experiments conducted on the ISS that JAXA says will be analyzed for medical purposes.

High-quality protein crystals obtained without being influenced by gravity will be helpful in exploring the causes of some diseases and developing medicines to cure them, according to the agency.

The samples will be transported on Tuesday to the Tsukuba Space Center, where they will be checked during the next few weeks.

In September, Japan's cargo vessel Kounotori7 was launched on an H-2B rocket, delivering the capsule and other supplies to the ISS.

The vessel departed from the space station on Thursday and released the capsule on Sunday morning before burning up with waste from the ISS when re-entering the Earth's atmosphere, JAXA said.