Jan. 24 (UPI) -- Assembly of the Artemis II moon rocket has reached its latest milestone with the stacking of the twin boosters' right forward center segment, NASA announced Friday. The most recent addition is the sixth of the 10 motor segments in the Artemis II Space Launch System rocket to be integrated onto mobile launcher 1 inside the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, according to an update from the space agency's Exploration Ground Systems Program.