Inside the mobile service tower at Cape Canaveral Air Force Station workers check the clearance of the STEREO spacecraft.

Inside the mobile service tower on Launch Pad 17-B at Cape Canaveral Air Force Station, workers check the clearance of the STEREO spacecraft as it is moved away from the opening. In the tower, STEREO will be mated with its launch vehicle, a Boeing Delta II rocket. STEREO stands for Solar Terrestrial Relations Observatory and comprises two spacecraft. The STEREO mission is the first to take measurements of the sun and solar wind in 3-dimension. This new view will improve our understanding of space weather and its impact on the Earth. The STEREO mission is managed by Goddard Space Flight Center. The Applied Physics Laboratory designed and built the spacecraft. The laboratory will maintain command and control of the observatories throughout the mission, while NASA tracks and receives the data, determines the orbit of the satellites, and coordinates the science results. STEREO is expected to lift off Oct. 25. Photo credit: NASA/George Shelton