This thesis evaluates mission scenarios using the existing Evolved Expendable Launch Vehicles for delivering the Crew Exploration Vehicle to the International Space Station. The Space Shuttle is scheduled to retire in the year 2011 and the Ares I is being developed to replace it. With its current schedule, the earliest that the Ares I will become fully operational is 2016. The configurations in this thesis are presented to narrow the gap in which the USA does not have direct access to the International Space Station. They also present "buy down" options for the USA human space operations, if the current development issues of the Ares I cause it to not become operational at all. The three Launch options presented are the Atlas V HLV, the Delta IV Heavy, and the Delta IV with three common core boosters as the first stage and the Orion service module to be used as the second stage. The first configuration, the Atlas V HLV requires significant impulse from the Orion service module in order to reach the final International Space Station orbit. The second option, the Delta IV Heavy, launches the Orion as a passive payload and requires no impulsive maneuvering from the service module in order to reach the International Space Station orbit. The third configuration, the Delta IV Heavy with three common core boosters as the first stage, and the Orion spacecraft acting as the second stage, requires significant impulse from Orion's service module engine to achieve the International Space Station orbit. After final orbit insertion all three configurations still have sufficient propellent for de-orbit and re-entry.The third configuration has a certain appeal, by eliminating the second stage only the common core booster on the Delta IV Heavy system need be human-rated. Finally, reliability and development cost assessments are presented and compared to the Ares I.