Ares I-X was an unmanned suborbital test flight for the Ares I rocket project. The objectives of the flight were to demonstrate controllability, perform in-flight staging at 130,000 feet, characterize roll torque at 150,000 feet, demonstrate first stage entry dynamics after staging, and assemble and recover the first stage. The test vehicle was 327 feet tall and weighed 1.8 million pounds at ignition, with a maximum acceleration of 2.5 g's and speed of Mach 4.8.