In accordance with the U.S. Vision for Space Exploration, NASA has been tasked to send human beings to the moon, Mars, and beyond. The first stage of NASA's new Ares I crew launch vehicle (Figure 1), which will loft the Orion crew exploration vehicle into low-Earth orbit early next decade, will consist of a Space Shuttle-derived fivesegment Reusable Solid Rocket Booster (RSRB); a pair of similar RSRBs also will be used on the Ares V cargo launch vehicle's core stage propulsion system. This paper will discuss the basis for choosing this particular propulsion system; describe the activities the Exploration Launch Projects (ELP) Office is engaged in at present to develop the first stage; and offer a preview of future development activities related to the first Ares l integrated test flight, which is planned for 2009. As part of the U.S. Vision for Space Exploration, NASA commissioned the Exploration Systems Architecture Study (ESAS) to provide recommendations for fulfilling the U.S. goals of providing human transportation to the International Space Station, returning to the Moon, and traveling on to Mars. The ESAS committee recommended using a two-vehicle approach for these missions, separating crew from cargo for added safety . 2 The Ares V cargo launch vehicle will go into orbit first, carrying the Lunar Surface Access Module in the Earth departure stage. Once the Ares V is in orbit, the Ares I crew launch vehicle will loft the Orion crew exploration vehicle into orbit to rendezvous with the Earth departure stage, which then ignites for the trans-lunar injection burn.The original configuration for Ares I would have used a four-segment RSRB for the first stage and a Space Shuttle Main Engine (SSME) for the upper stage, while the Ares V would have used five SSMEs and two five-segment RSRBs for its core stage, followed by a Saturn-derived J-2X engine for the Earth departure stage . 3 After further engineering and business studies showed it would be more expensive to redesign the SSME to ignite in the upper atmosphere, the Constellation Program accepted the ELP team's recommendation to use a derivative of the J-2 engine that powered the Saturn V third stage to the Moon. However, because the J-2X produced less thrust than the SSME, the first stage needed to be upgraded to provide additional thrust. This change proved valuable for two reasons: The five-segment RSRB still uses Shuttle-derived hardware, allowing NASA to draw upon existing institutional knowledge and infrastructure. The five-segment RSRB is also part of the Ares V core stage, so ELP can apply test data, hardware, and lessons learned by experienced personnel from Ares 1 to Ares V development.ELP will benefit from the Space Operations Mission Directorate's long experience operating the four-segment Shuttle booster, as the five-segment unit will use the same casing, propellant, thrust vectoring system, and a similar nozzle design. ELP will also gain valuable assistance from the Shuttle Program in developing the five-segment motor, as both directorate...

The National Aeronautics and Space Administration (NASA) Ares Projects Office (APO) is continuing to make progress toward the final design of the first stage propulsion system for the Ares I crew launch vehicle and the Ares V cargo launch vehicle. Ares I and Ares V will provide the space launch capabilities necessary to fulfill NASA' s exploration strategy of sending human beings to the Moon, Mars, and beyond. As primary propulsion for both the Ares I and Ares V, the Space Shuttle-derived Reusable Solid Rocket Motor (RSRM) is one of the first and most important components to be tested. The first flight of Ares I, called Ares I,X, will occur in April 2009. The Ares I-X flight will use a combination of flight and simulation hardware to obtain data on controlling the long and narrow crew launch vehicle configuration.The test will use a four-segment RSRM from the Shuttle inventory and a fifth spacer segment to simulate the size and weight of the operational five-segment motor that will be used on later flights. Manufacturing work has begun on the fifth space segment. The upper stage, Orion crew exploration vehicle, and launch abort system will all be replaced with simulator hardware. Ares I-X will be controlled by Atlas V avionics adapted to control the first stage. That hardware is undergoing hardware-in-the-loop testing in a contractor-provided systems integration laboratory (SIL) and will complete its critical design review (CDR) in December 2007. Drogue and main parachute drop tests have also been conducted successfully at Yuma Proving Grounds, allowing the First Stage Element team to proceed with fabricating parachutes for Ares I-X. The Ares I-X flight test will be the first flight test for the parachutes as well. A series of preliminary design technical interchange meetings is being conducted prior to the Ares I-X CDR in January 2007 to ensure readiness for the flight.A series of preliminary design activities associated with each booster subsystem has been the focus of much activity in 2007. These events will culminate in a formal preliminary design review in 2008. Subsystems and component specifications will be developed, associated analyses and drawings will be evaluated for technical adequacy given the system requirements that have been baselined.The first stage has been undergoing a series of trade studies to determine means for upgrading booster performance and reducing operational costs. Performance improvement studies have included a change from polybutadiene acrylonitrile (PBAN) propellant to hydroxyl-terminated polybutadiene (HTPB); from aluminum to composite motor casings; and optimized or upgraded propellant gram and nozzle structures. Some or all of these changes could result in a block upgrade to the Ares I first stage, after becoming the standard configuration for the Ares V. The cost reduction studies included a change from reusable or recoverable boosters to completely expendable boosters; changing from hydrazine-powered to more environmentally friendly electrohydrostatic actuators (EHA...

With a mission to continue to support the goals of the International Space Station (ISS) and explore beyond Earth orbit, the United States National Aeronautics and Space Administration (NASA) is in the process of launching an entirely new space exploration initiative, the Constellation Program. Even as the Space Shuttle moves toward its final voyage, Constellation is building from nearly half a century of NASA spaceflight experience, and technological advances, including the legacy of Shuttle and earlier programs such as Apollo and the Saturn V rocket. Out of Constellation will come two new launch vehicles: the Ares I crew launch vehicle and the Ares V cargo launch vehicle. With the initial goal to seamlessly continue where the Space Shuttle leaves off, Ares will firstly service the Space Station. Ultimately, however, the intent is to push further: to establish an outpost on the Moon, and then to explore other destinations. With significant experience and a strong foundation in aerospace, NASA is now progressing toward the final design of the First Stage propulsion system for the Ares I. The new launch vehicle design will considerably increase safety and reliability, reduce the cost of accessing space, and provide a viable growth path for human space exploration. To achieve these goals, NASA is taking advantage of Space Shuttle hardware, safety, reliability, and experience. With efforts to minimize technical risk and life-cycle costs, the First Stage office is again pulling from NASA's strong legacy in aerospace exploration and development, most specifically the Space Shuttle Program. Trade studies have been conducted to evaluate life-cycle costs, expendability, and risk reduction. While many first stage features have already been determined, these trade studies are helping to resolve the operational requisites and configuration of the first stage element. This paper first presents an overview of the Ares missions and the genesis of the Ares vehicle design. It then looks at one of the most important trade studies to date, the "Ares I First Stage Expendability Trade Study." The purpose of this study was to determine the utility of flying the first stage as an expendable booster rather than making it reusable. To lower the study complexity, four operational scenarios (or cases) were defined. This assessment then included an evaluation of the development, reliability, performance, and transition impacts associated with an expendable solution. This paper looks at these scenarios from the perspectives of cost, reliability, and performance.