STS-216 delivered the Main Central Truss segment to the station. The role of the Truss Assembly on the station is to provide an area to attach experiments to the outside of the station, provide the attachment points for the stations radiator system, and to provide a home for the station arm. STS-216 was also one of the view missions were the shuttle had no choice but to land at night. On all missions, there are two windows of opportunity each day for a landing at Cape Canaveral. On most missions, at least one of the windows is during the day. However, since the windows are less then 12 hours apart, on missions both windows fall during night time hours (one just after sunset, and one just before sunrise).