Workers keep watch as the Ares I-X aft booster segment with the aft skirt is lowered toward the mobile launch platform in High Bay 3.

In the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida, workers keep watch as the Ares I-X aft booster segment with the aft skirt is lowered toward the mobile launch platform in High Bay 3. This is the start of the buildup of the Ares I-X launch vehicle for the flight test targeted for no earlier than Aug. 30. Part of the Constellation Program, the Ares I-X is the test vehicle for the Ares I, which is the essential core of a space transportation system that eventually will carry crewed missions back to the moon, on to Mars and out into the solar system. Photo credit: NASA/Jack Pfaller