The World's Largest Stick of Dynamite
Just when it seemed like the history books had been closed on the Challenger disaster, I came across a review of Truth, Lies & O-Rings, an interesting look at the faulty decision-making leading up to launch. (hat tip to Clark Lindsey's Hobbyspace.) The reviewer makes an interesting point about the dangers inherent in ground handling of solid rockets. Many of the inherent disadvantages of SRBs have been long-discussed, such as the inability to shut them down during abort situations. But handling and storing the motors carries all the potential dangers of riding on them. For that reason, SRB stacking operations are classified as “hazardous operations,” and all non-essential personnel are banned from the Vehicle Assembly Building. The procedure is similar for stacking the stages of other solid-fuel launch vehicles. In spite of all the precautions and built-in safety mechanisms, the potential always exists for a catastrophic solid-fuel detonation, as occurred with Brazil’s orbital launch vehicle.
While I tend to think that the risk is overstated (the industry has been dealing with large solid rockets since the 1940’s,) it can never be entirely eliminated. For this reason, Jeff Bell predicted that the SRB would be deleted from the shuttle-derived launch vehicles under development by NASA. Many “space boosters” are dismissive of Jeff Bell, viewing him as a cynic whose arguments aren’t worth the paper they’re written on. I’ll concede that his predictions often come with fatal flaws, but he does make a lot of solid arguments and presents plenty of pertinent facts. In the case of the aforementioned prediction, Jeff Bell’s fatal flaw is assuming that NASA would choose a safe, clean-sheet launcher design over one that protects the shuttle’s entrenched workforce and contractors.
The ground-handling of large solid rockets (and even the individual segments) was an issue that should have been re-examined when Ares I was designed to be "safe, simple and soon." While NASA personnel have done an admirable job in handling the SRB's up to this point, it's sobering to know that just one mistake could cost a lot of lives and pull the plug on the nation's manned space program. The Ares 5-segment SRB will be the world's largest stick of dynamite, and that risk should never be lost on anybody who works in the space business.