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NASA’s new Ares Rockets

Published on Jul 25, 2006 at 1:06 am. 1 Comment.
Filed under NASA, rockets, space exploration.

NASA has released the names of the new rockets being developed for the next generation of launch vehicles to replace the Space Shuttle fleet. Two rockets are being developed. One is to lift the new Crew Excursion Vehicle (CEV), and another is a heavy lift booster. Both are named Ares. This is apropos because Ares is the Greek god of war, and is synonymous with the Roman god Mars. Ultimately, NASA hopes for the CEV to be a multipurpose craft, carrying astronauts to the International Space Station, going to the Moon, as well as being part of a manned Mars mission. The rockets are to be called Ares I and Ares V. When, I first read that, I thought, â€œHuh? What happened to II, II, and IV?â€ But, apparently the numbering scheme is in tribute to the Apollo era Saturn I and Saturn V rockets. Those numbers were such, though, because there actually were other Saturn rockets designed, but never built. Both rockets are legacies of both Apollo and Shuttle technology.Â

The Ares I rocket is designated as a two stage rocket, with the CEV and its service module sitting on top of it. The service module will have its own engine, so this is almost like a three stage rocket, depending upon how you look at it. However, the CEV can be replaced with a satellite or other payload up to about 50,000 pounds for delivery to low Earth orbit (LEO). The Ares I first stage is a five segment solid rocket motor, very similar to the solid rocket boosters used on the Space Shuttle. This solid rocket first stage burns polybutadiene acryonitrile that is shaped inside the solid rocket segments to form its own combustion chamber, a typical solid rocket, in other words. ATK Thiokol is the prime contractor for the first stage. At about 200,000 feet altitude, the first stage separates and falls back towards Earth. At low enough altitude, parachutes deploy, and it splashes down in the Atlantic Ocean, where it can be retrieved and the segments refurbished and reused. This makes the Ares I a partially reusable rocket, in keeping with the goal of reusability that was a driving factor behind the design of the Space Shuttle. The CEV is also reusable. The Ares I second stage is an all new design, but it is powered by a Pratt & Whitney Rocketdyne J-2X engine, a direct descendent of the J-2 engines that powered the upper stages of the Saturn I-B and Saturn V rockets. The J-2X engine is fueled by liquid hydrogen and liquid oxygen. The CEV and its command module sit atop the Ares I second stage.

The Ares V rocket will be NASAâ€™s new heavy lift vehicle. Under the current plan for a return to the Moon mission, two rockets will lift the lunar hardware into space. With Apollo, one rocket, the Saturn V, carried everything. Now, the Ares V will carry the lunar lander, ascent stage, and lunar rocket stage into orbit. The Ares I will ferry the astronauts to orbit, where they will dock with the lunar hardware. This is similar to the strategy adopted by the Soviet Union in their manned Moon program. Of course, the Soviet manned Moon program never got to the Moon. Presumably, we can do better.

The Ares V is also designated a two stage rocket. The first stage is a compound system, consisting of two solid rocket boosters and a liquid fueled central core rocket stage. The flanking solid rockets are to be extremely similar to the solid rocket primary booster for the Ares I. This is expected to cut costs, because the same facilities can be used to manufacture and handle both forms of the solid rockets. The first stage central core will be similar to an upgraded Shuttle external fuel tank, filled with liquid hydrogen and liquid oxygen. These propellants will fuel the central coreâ€™s five RS-68 engines, also manufactured by Pratt & Whitney Rocketdyne. The Ares V upper stage is another brand new structure with a J-2X engine, similar to the upper stage of the Ares I, but with more propellant. When used for a lunar mission, the upper stage is the Earth Departure Stage (EDS). The first stage lifts the EDS into orbit, where the CEV docks with it. Then, the EDS fires to push the CEV, lunar lander, and all associated hardware to the Moon. A payload of up to 144,000 pounds can be sent to the Moon. However, if not going to the Moon, the Ares V will be able to lift 290,000 pounds into LEO.

Together, these rockets are supposed to be the next generation of crewed vehicles. The CEV is a capsule design, similar to the original spacecraft. The rockets are based on technology derived from reliable Shuttle and Apollo rockets. Only the structures for the upper stages are totally new systems (other than the CEV). The uniform design and reusability of the solid rocket components are expected to keep costs lower than fully expendable rockets. However, things have a way of not quite working out as NASA expects. The Shuttle is a case in point. Weâ€™ll have to wait and see how the Ares rockets turn out. The plans look good, though.

-Astroprof