SPACE PROPULSION 3- ADVANCES

SPACE PROPULSION-3

Advanced Solid Rocket Booster

NASA was planning on replacing the post-Challenger SRBs with a new Advanced Solid Rocket Booster (ASRB) to be built by NASA itself at a new facility, on the location of a canceled Tennessee Valley Authority nuclear power plant, at Yellow Creek, Mississippi. The ASRB would have produced additional force in order to increase shuttle payload, so that it could carry modules and construction components to the ISS. After an expenditure of over $2 billion USD, the ASRBs were canceled in favor of the "Super Light-weight Tank" (SLWT) that is in use now, replacing the light-weight tank design that was used on earlier flights.

Two ASRB casings can be found on the Space Shuttle Pathfinder on display at the United States Space & Rocket Center in Huntsville, Alabama.

Filament-wound cases

In the need to provide the necessary thrust to launch polar-orbiting shuttles from the SLC-6 launch pad at Vandenberg Air Force Base in California, SRBs using filament-wound cases (FWC) were designed to be more lightweight than the steel cases used on KSC-launched SRBs.[7] Unlike the regular SRBs, which had the flawed field joint design that led to the Challenger Disaster in 1986, the FWC boosters had the "double tang" joint design (necessary to keep the boosters properly in alignment during the "twang" movement when the SSMEs are ignited prior to liftoff), but used the two O-ring seals. With the closure of SLC-6, the FWC boosters were scrapped by ATK and NASA, but their field joints, albeit modified to incorporate the current three O-ring seals and joint heaters, were later incorporated into the present-day field joints on the current SRMs.


Five-segment booster

Prior to the destruction of the Space Shuttle Columbia in 2003, NASA investigated the replacement of the current 4-segment RSRMs with either a 5-segment SRB design or replacing them altogether with liquid "flyback" boosters using either Atlas V or Delta IV EELV technologies. The 5-segment SRB, which would have required little change to the current shuttle infrastructure, would have allowed the space shuttle to carry an additional 20,000 lb (9,100 kg) of payload in an International Space Station-inclination orbit, eliminate the dangerous "Return-to-Launch Site" and "Trans-Oceanic Abort" modes, and even fly polar-orbiting missions from Kennedy Space Center using a so-called "dog-leg" maneuver over the Atlantic Ocean. With the destruction of the Columbia, NASA has shelved the 5-segment SRB for the shuttle program, but resurrected it for the Ares I and Ares V boosters for Project Constellation.

Future and proposed uses

NASA plans to reuse the SRB designs and infrastructure in several Ares rockets. In 2005, NASA announced the Shuttle-Derived Launch Vehicle slated to carry the Orion Crew Exploration Vehicle into low-Earth orbit and later to the Moon. The SRB-derived Crew Launch Vehicle (CLV), named Ares I, originally featured a modified 4-segment SRB for its first stage, while a liquid-fueled second stage, powered by a single main engine, would have propelled the Orion into orbit. Its current design, initially introduced in 2006, and since modified, is to feature the originally planned, but scrapped 5-segment SRB first-stage, with a second stage powered by an Apollo-derived J-2X rocket engine. In place of the standard SRB nosecone, Ares I will have a tapered interstage assembly connecting the booster proper with the second stage, an inflatable ring to counter the end-over-end spinning, and larger, heavier parachutes to lower the stage into the Atlantic Ocean for recovery.

Also introduced in 2005, was a heavy-lift Cargo Launch Vehicle (CaLV) named Ares V. Early designs of the Ares V utilized five SSMEs and a pair of 5-segment boosters like those planned for the pre-Columbia upgrades, but since then NASA had redesigned the vehicle using first five, and now six RS-68B rocket engines, with either the originally-planned 5-segment boosters or a pair of 5.5-segment boosters (similar to the 5.5-segment booster configuration on the now-retired Titan 34-D/Centaur rocket used to launch the Viking and Voyager spacecrafts in the mid-1970s).

The current redesign will make the booster taller and more powerful than the now-retired Saturn V, N-1, and Energia rockets, and will allow the Ares V to place both the Earth Departure Stage and Altair spacecraft into Low-Earth orbit for later on-orbit assembly. Unlike the 5-segment SRB for the Ares I, the 5 or 5.5-segment boosters for the Ares V are to be identical in design, construction, and function to the current SRBs except for the extra segments. Although there is no final decision on the recovery or reuse of this system, but it is most likely that the standard recovery process like that employed on the shuttle will be used. Like the current shuttle boosters, the Ares V boosters will fly an almost-identical flight trajectory from launch to splashdown.

The DIRECT proposal for a new, shuttle-derived launch vehicle, unlike the Ares I and Ares V boosters, uses a pair of classic 4-segment SRBs with the existing RS-68 engines used on the Delta IV EELV rocket.