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This article is about the Ares I launch vehicle. For other uses, see Ares (disambiguation). The Ares I (aka "the Stick" -- formerly known as the Crew Launch Vehicle or CLV) is the vehicle that will launch the proposed Orion spacecraft after the end of the Space Shuttle flight program in 2010. The name "Ares" is from the Greek god of war (Mars in Roman Mythology – as NASA plans to fly manned missions to Mars after 2030), while the "I" refers to the single SRB in the first stage, and as a nod to the Saturn I and Saturn IB rockets used by NASA during the Apollo Program between 1963 and 1975. The larger, unmanned Ares V cargo launch vehicle will be used to launch the Lunar Surface Access Module into a low-Earth orbit for later retrieval by an Orion crew.
Design Using hardware ostensibly derived from the current Space Shuttle (but see below), along with hardware developed from the Apollo Program, the Ares I launcher is designed to be a "staging" rocket (where rocket components drop off after being used) instead of a "thrust-assisted" takeoff rocket like that of the current Shuttle stack (or in some cases, the Titan III and Titan IV rockets). As currently defined, the Ares I will use a 5-segment version of the Space Shuttle Solid Rocket Booster (SRB) for its first stage, with a liquid-fueled second stage powered by a single J-2X rocket engine derived from the Saturn IB and Saturn V rockets. The Orion spacecraft will be the primary payload, and, like its Apollo spacecraft predecessor, will be mounted on the top of its booster, eliminating the possibility of the Orion's heat shields being damaged by debris shaken from the launch vehicle, the primary cause of the destruction of the Space Shuttle ''Columbia'' in 2003. The Ares I launch vehicle will also be used to launch the unmanned cargo supply version of the Orion, as well as unmanned satellites weighing at or less than 25 metric tons, roughly the same weight that can be lifted by the Atlas V and Delta IV EELV rockets. The usefulness of Ares I in this latter role will be restricted because the vehicle will launch its payload into an initial orbit whose perigee is within the Earth's atmosphere; consequently the payload will need to be able to adjust its own orbit, requiring a rocket motor (something that is eliminated with the Atlas V and Delta IV). Because of its tall, slender design, along with the staging design, the Ares I was given the nickname "The Stick," in playful reminiscence of the Saturn V's nickname, "The Stack" (due to the "stacking" of the three stages on top of each other). Design History "NASA selected a Shuttle-derived launch architecture after a thorough apples-to-apples study... the Exploration Systems Architecture Study. NASA carefully weighed a wide variety of launch options for both crew and cargo - a Shuttle derived architecture was the clear winner when considering total cost, schedule and safety/reliability to achieve an exploration-capable system. NASA did not do this in a vacuum - in fact, we received inputs from industry, including studies funded by the agency, in the year prior to ESAS. The ESAS results were independently reviewed and concurred-in by experts outside the agency. Last Winter and Spring, after a series of trade studies, NASA elected to alter the launch architecture to a 5 segment RSRM-derived 1st stage and a J2X upperstage for Ares I and an Ares V core stage powered by an RS-68 (still boosted with a 5 segment RSRM and a J-2X earth departure stage)." A Shuttle-derived launch architecture was selected by NASA for the Ares I. Originally, the vehicle would have used a 4-segment Solid Rocket Booster (SRB) for the first stage (with the Space Shuttle External Tank attachment points removed and a new interstage assembly replacing the nosecone), with a simplified Space Shuttle Main Engine (SSME) being used for the second stage. An unmanned version, identical with the current design, would have used the 5-segment booster, but with the second stage using the single SSME. But shortly after the initial design was approved, additional tests revealed that the Orion spacecraft would be too heavy to be lifted with the 4-segment booster, so in January, 2006, NASA announced that the Orion spacecraft would be slightly reduced in size, a fifth segment would be added to the solid-rocket first stage, and that the single SSME would be replaced with the Apollo-derived J-2X motor. While the switch from a 4-segment first stage to a 5-segment version would allow NASA to construct virtually identical motors (albeit with some segments being interchangeable), the main reason for the need of the 5-segment booster was the need to adopt the J-2X. At approximately $20-25 million USD per engine, the Rocketdyne-designed and produced J-2X is less than half that of the complex SSME (≈$55 million USD), and unlike the current SSME, which was designed to start on the ground, the J-2X was designed from the start to be started in both mid-air and in near-vacuum, and was critical, especially the original J-2 engine used on the Saturn V's S-IVB stage, to propel the entire Apollo spacecraft to the Moon. The SSME, on the other hand, would have to undergo extensive modifications to be air-startable, be able to restart in a vacuum (as the Ares I would fly a "direct-insertion" profile, and that the Orion spacecraft has limited fuel reserves), and would have to be "pre-fired" in a manner similar to the "Main Engine tests" conducted on the SSMEs prior to the maiden flights of each NASA orbiter and before the STS-26 flight in 1988. NASA has announced that ATK Thiokol, the current builders of the Shuttle SRBs, will be the prime contractor for the Ares I first stage *; ATK is also bidding to become part of the consortium that will build the Ares I upper stage. Rocketdyne, a division of Pratt & Whitney (formerly under the ownership of Rockwell International and Boeing's North America division), will be the main subcontractor for the J-2X rocket engine. Testing of the engine is currently underway at a facility north of Huntsville, AL. Nomenclature The name Ares I was officially announced on June 30, 2006 on the NASA website. Test flights In October 2006 NASA released a draft schedule of all planned NASA Project Constellation missions through 2019 *. This document included descriptions of a series of proposed vehicle test missions.
Given a successful testing regime, the initial manned launch of the complete Ares I/Orion vehicle is expected to follow in 2015. Vehicle Specifications Criticism of the Ares I The proposed Ares I configuration has been criticised on several grounds. Firstly, the production of a launch vehicle in the 25 metric ton payload class can be seen as direct competition with existing vehicles, e.g. the Boeing Delta IV-Heavy. It can be argued that lower costs and improved safety are likely to result from the use of an existing vehicle, since it would have lower development costs, a proven track record, and would benefit from a higher flight rate. Secondly, the configuration chosen by NASA requires a new 5-segment SRB with its associated $3 billion development cost; this negates many of the supposed advantages of using 'shuttle-derived' hardware. In fact, critics say, the deletion of the SSME and 4-segment SRB from the configuration removes the new vehicle from the class "Shuttle Derived Launch Vehicles" entirely. Thirdly, technical objections may be raised over the aerodynamic stability of the proposed configuration. The tall, slender 'stick' configuration leads to a forwards centre of pressure and an aft centre of gravity. Thus, the Ares I will continually tend to turn around, being most stable if flying backwards. The thrust vector control system on the SRB will have to constantly cope with this instability, which may lead to increased mechanical loads on the airframe. However, supporters of the Ares I claim that the vehicle is essential in ensuring the continued employment of the current STS workforce, as well as those involved developing a critical component (the five segment SRB) of the larger Ares V vehicle. Prior to the Columbia accident in 2003, NASA, in trying to keep the Space Shuttle flying safely until 2025-2030, had looked into the 5-segment booster design or a new liquid-fueled "fly back" booster that would have allow the Shuttle to carry extra-heavy payloads to the International Space Station, along with some components to earlier "return-to-Moon" or Mars missions. The 5-segment booster, which would have required the fewest modifications to the existing ground facilities, would have eliminated the potentially disastrous Return-To-Launch-Site (RTLS) abort and allow the Shuttle to fly an intact abort all the way to either Edwards Air Force Base in California or the White Sands Missile Range in New Mexico. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
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