NASA announced on 30-June-2006 the names of the next generation of launch vehicles that will return humans to the moon and later take them to Mars and other destinations. The Crew Launch Vehicle (CLV) will be called Ares I, and the Cargo Launch Vehicle (CaLV) will be known as Ares V.
Since the original CLV and CaLV plans were announced in 2005, several design modifications have been made to both launch vehicles.

Ares I (CLV):
• Stage 1 has been upgraded from a 4-segment RSRM to a 5-segment RSRM.
• Stage 2 engine has been changed from a single SSME to one Rocketdyne J-2X engine.

Ares V (CaLV):
• Booster  has been upgraded from a 5-segment RSRM to a 5.5-segment RSRM.

• Stage 1   engines have been changed from five SSME to six Rocketdyne RS-68 engines.
                  diameter has been increased from 8.4 m to 10.0 m to accomodate greater propellant load.
• Stage 2   engine has been changed from two Rocketdyne J-2S to one Rocketdyne J-2X engine.
                  diameter has been increased from 8.4 m to 10.0 m to accomodate greater propellant load.
 

Ares I is expected to become the third human space launcher developed entirely by the U.S. National Aeronautics and Space Administration (NASA). Ares I is being developed to do just one job - launch the Orion Crew Exploration Vehicle. Orion is planned to carry on NASA's human spaceflight efforts after Space Shuttle is retired in 2010.
As currently envisioned, the Ares I Crew Launch Vehicle will consist of a five-segment solid propellant first stage derived from Space Shuttle's four-segment reusable solid rocket booster (RSRM) topped by an all-new liquid hydrogen/oxygen upper stage. The upper stage will be powered by a new J-2X upper stage engine derived, in part, from the J-2 engine used on Apollo/Saturn upper stages and the simplified J-2S engine developed but never flown.
Mission requirements call for the two-stage launch vehicle to be capable of inserting a 23.27 tonne Orion spacecraft into a -20x185 km x 28.5 deg suborbital trajectory. This will aim the spent Ares I second stage toward an Indian Ocean impact while Orion fires its service module engine to complete the ascent to orbit. A service module burn at first apogee would need to provide 62 meters per second of additional velocity to circularize the orbit at 185 km, which is roughly the same as the "OMS-2" burn used to complete the space shuttle ascent to orbit.

The Ares I/Orion stack is expected to weigh about 912 tonnes at liftoff and stand nearly 100 meters to the tip of the launch abort system mast. The launch vehicle itself will be about 78.5 meters from its base to the top of its Instrument Unit. The first stage will be 3.71 meters in diameter, the upper stage 5.5 meters in diameter, and the Orion spacecraft will be 5 meters in diameter.
The first stage will produce roughly 1,588 tonnes of thrust at liftoff and will average 1,245 tonnes of thrust during its roughly 126 second burn. Approximately 627 tonnes of polybutadiene acrylonitride (PBAN) solid propellant will be consumed during the burn. The movable RSRM nozzle will provide pitch and yaw control while a new monopropellant roll control system located in the interstage will control vehicle roll during the first stage burn.

A cylindrical interstage will connect the RSRM and upper stages. It will be composed of composite materials, marking the first large-scale use of a composite structural element in a U.S. human-rated launch vehicle. The interstage will contain important propulsion elements, including the first stage roll control system, the booster separation motors (the 8.39 tonne thrust motors currently located in the RSRM nose), and two interstage separation systems. Current plans call for the roll control system to use monopropellant hydrazine thrusters. Thrust will be produced by the decomposition of hydrazine as it passes through a catalyst bed.
The upper stage J-2X engine will burn liquid hydrogen and liquid oxygen for about 465 seconds, producing 133 tonnes of thrust at a 448 second vacuum specific impulse.
The J-2X engine will swivel to provide pitch and yaw control. Roll control will be provided by a blow-down system feeding monopropellant hydrazine to a series of attitude control thrusters. Small solid motors will fire to separate the upper stage from the interstage and to settle propellants.
An aft liquid oxygen tank will be topped by a forward liquid hydrogen tank, with a common bulkhead between, to compose the upper stage structure. The tanks will hold more than 139 tonnes of propellant. Tanks will be fabricated from the same 2195 aluminum-lithium alloy currently used to build shuttle External Tanks. The stage itself will be assembled at the current Michoud External Tank factory in New Orleans.