Boeing is competing to produce the Ares I crew launch vehicle upper stage and instrument unit as shown in this artist's rendition of the major components. The instrument unit contains the guidance systems and avionics and sits on top of the upper stage, but below the crew exploration vehicle. Ares I, which will transport the Orion crew exploration vehicle to low Earth orbit, is an essential element of the nation's space exploration program that will return astronauts to the moon no later than 2020.