Spaceflight Now

STS-121 Launch Windows
Updated: June 30, 2006

Changes and additions:
- May 11: Posting initial windows chart
- June 12: Updating times for July 1 and 2
- June 20: Updating times throughout
- June 30: Updating launch windows for July 1-3

To reach the international space station, the shuttle must launch within about five minutes of the moment Earth's rotation carries the launch pad into the plane of the station's orbit. For STS-121, launch must occur in daylight and the external fuel tank must separate in orbit, on the other side of the planet, with enough sunlight to allow photo documentation of the tank. Those factors, plus temperature issues based on the angle between the plane of the space station's orbit and the sun result in the following launch windows for shuttle mission STS-121 in July (these times will be tweaked as launch approaches based on the station's actual orbit).

To maximize performance, NASA targets launch for right around the moment the shuttle can launch directly into that plane. In the chart below, the target launch time is listed in the "in plane" column. All times in EDT and subject to change.