Complex sentence: In 2161, the starship "Enterprise" and its crew return to Earth on the eve of the signing of the Federation charter; after ten years of service, the "Enterprise" is due to be decommissioned.
Split into simpler sentences: In 2161, the starship "Enterprise" and its crew return to Earth on the eve of the signing of the Federation charter. After ten years of service, the "Enterprise" is due to be decommissioned.