NASA is planning to extend its Ares I crew launch vehicle's solid rocket booster first-stage nozzle in time for the maiden lunar mission, to deliver improved performance.

The agency recently completed its preliminary design review for the booster's first stage, which will launch the Orion crew exploration vehicle to the International Space Station from March 2015.

However, the nozzle extension will be a later addition. In another change from the original plan, to have the same solid rocket booster for Ares I and the Ares V cargo launch vehicle's (CaLV) strap-on boosters, the CaLV's solid rockets are to be longer.

Extending the nozzle is "a requirement for lunar missions, beginning with the Orion 13 flight. The plan is to incorporate the extended exit cone in time to support that mission," says Ares I first-stage manager Alex Priskos.

The first-stage preliminary design review did not address the solid rocket booster's thrust oscillation problem because studies are still under way.

NASA may have a "delta" preliminary design review, according to Priskos, for subsystems addressing oscillation. The agency has proposed first-stage spring-loaded masses as one solution.

Due to the first-stage's launch acceleration, the rocket's umbilical connections will have Ares I specific designs and not heritage hardware.

Priskos says that "specific hardware interface responsibilities between Ares and ground operations have been defined", deciding who designs what, and that each design is at a "different point in design maturity".

Meanwhile, the first-stage drogue and other parachute drop tests' data gathered has been used to optimise reefing line lengths for the 2009 Ares I-X flight test and mature ongoing recovery system design work.

Source: Flight International