The Upper Stage is vital because it will provide the final boost to send humans into Earth orbit. The Ares I First Stage is a single, five-segment reusable solid rocket booster, derived from the Space Shuttle Program’s four-segment reusable solid rocket booster. The second stage, or Upper Stage, is being designed at Marshall Space Flight Center with support from Glenn. The Ares I Upper Stage is propelled by a J-2X main engine fueled with liquid oxygen and liquid hydrogen.

The primary mission of Ares I—and its 50,000-pound payload capacity—is to carry crews of up to six astronauts to Earth orbit. During the first two-and-a-half minutes of flight, the First Stage booster powers the vehicle to an altitude of about 38 miles and a speed of Mach 5.9 (almost 6 times the speed of sound). After its propellant is spent, the reusable booster separates and the Upper Stage’s J-2X engine ignites and powers the vehicle to an altitude of about 83 miles. Then, the Upper Stage separates and Orion's service module propulsion system completes the trip to a circular orbit 185 miles above Earth.

As of October 2007, the Ares I Upper Stage Project completed its System Definition Review and is entering its Preliminary Design phase.

Glenn Support to Ares I Upper Stage

In support of the Upper Stage Project Office at NASA Marshall, Glenn is designing and developing the following subsystems and components:

• Thrust Vector Control (TVC) Subsystem – consists of power and actuation components that control the main engine’s direction (thrust vector) in order to steer the vehicle and keep it on course.
  
  
• Avionics Subsystem:
  
  
• Electrical Power System (EPS) that provides all the electrical power for the Upper Stage throughout the entire mission.
• Development Flight Instrumentation (DFI) system consisting of instrumentation to acquire flight data to help validate the vehicle’s performance during initial development flights.
• Sensors: Advanced, miniature hydrogen leak detection sensors and software that automate sensor data qualification.
  
  
• Structures and Thermal Subsystem – purge and hazardous gas leak detection systems for the Upper Stage’s closed compartments.