Mission controllers in Houston commanded the Canadarm2 robotic arm to release an external pallet loaded with the 2.9 tons of nickel-hydrogen batteries into Earth's orbit Thursday morning.

"It is safely moving away from the station and will orbit Earth between two to four years before burning up harmlessly in the atmosphere," NASA said in a statement.

NASA representative Leah Cheshier confirmed to Gizmodo that the pallet is the largest object "mass wise" ever to be dispelled from the ISS.

"More than twice the mass of the Early Ammonia Servicing System tank jettisoned by spacewalker Clay Anderson during the STS-118 mission in 2007," Cheshier said.

The external pallet was left on the space station by the final HTV supply ship last May, as the batteries were replaced with more powerful lithium-ion power storage units.

Originally, the batteries were supposed to be placed inside an HTV and released from the ISS burning up upon re-entry> However a tedious spacewalk Feb. 1 by astronauts Mike Hopkins and Victor Glover disrupted the mission schedule and left the pallet attached to the space station.

Cheshier assured that ballistics officers "indicate no threat" of the pallet colliding with other space objects, but added that it will be tracked by the U.S. Space Command.