Chair Force Engineer

Thursday, July 27, 2006

Three Segments, Making Zero Sense

The return-to-the-moon plan has been through so many changes since the ESAS report last September that it's enough to make your head spin. Adding to the confusion is an alternative to the stick-like Ares I: a new rocket using the Shuttle ET, J-2X engines, and three-segment SRB's.

Supposedly, the new "2x3" rocket (aka "Stumpy") is viewed as a backup if the 5-segment SRB runs into problems. The logic of this statement boggles me. After all, solid rockets can't be stretched or shortened without major modifications. The thrust and burn rate of the solid rocket are functions of the propellant grain's length and the shape of the grain. Whether the SRB is shortened or stretched, a change to the grain shape will be required. In defense of the 5-segment SRB, ATK-Thiokol has at least done this work for the 5-segment SRB, to the point where two have been static-fired. This work isn't as far along for the 3-segment SRB concept.

NASA is running into all sorts of problems with Ares I (whether the final vehicle looks like a stick or a stump) because the rocket has been a kludge since the start, when it emerged as a half-baked thought in the brain of Scott Horowitz. While the ESAS report had some equally half-baked reasons for choosing Ares I over the Delta and Atlas, the truth is that NASA wants a vehicle it has control over, and they want a vehicle that will keep the shuttle's standing army employed in the years after the Orbiter's retirement in 2010. NASA has between now and 2014 to work all of the bugs out of Ares I to the point where a human crew can fly on it. Can it be done, within the confines of NASA's tight budget, even as NASA continues to revisit and revise the design? I am deeply skeptical that it can happen.

NASA is losing sight of the vision, and Ares I will be "the stick" that breaks the camel's back unless the cost and schedule baselines can be saved. Cancel the Ares I right now, and launch the CEV capsule on a minimally-modified Delta IV Heavy. Use the saved money to accelerate CEV development (to support a 2012 first flight) and accelerate the Ares V (which should be scaled back to maximize commonality with the shuttle and Delta IV.)