Jones: Crippling delays are a possibility. If an ISS component goes up on Shuttle and either does not make it into place or has to be returned due to a systems problem, the next mission can’t take place. We will then face an operational review and the time to make a technical fix. I would find it hard to believe that we’ll build the entire ISS without at least one major hang-up in assembly. The transfer of the P6 truss segment (furling of its solar panels, dismounting, transit by mobile transporter (robot arm cart), and reinstallation and deployment of the arrays) is one example where a big snag could develop. But lunar missions, along with asteroids and Mars, will be just as challenging. We should try to do the job rather than give up prematurely. I would say we have an 80% chance of pulling off the Shuttle’s ISS assembly work.
I am a little skeptical of the priority and popularity of projects like Terrestrial Planet Finder, which exist only on paper and are just one of many steps toward finding habitable worlds. Mars is indeed a habitable world, given its resources, and establishing humans off-planet, where they can investigate Mars’ biological history (if one exists), would seem of more immediate interest and excitement to the public. It’s possible to do robotic exploration and astronomy in tandem with human expeditions. After all, if we find Earth-like planets, it will be centuries before a machine can visit them. Mars is a near-term destination likely to be visited in our lifetimes, or shortly thereafter.
Americans won’t care if we don’t build a TPF as soon as possible. They will care if the Chinese and Russians are taking circumlunar flights and we have no Low Earth Orbit-capable transport or access.
Reichhardt: Is there something NASA can do to improve its odds of successfully flying the Shuttle for four more years? During the CAIB hearings [Chairman] Hal Gehman called for an aggressive program to search for unknown engineering problems—“looking for trouble,” he called it. Is that happening to the extent that it should? Or would that even help at this stage of the program?
Hubbard: The issue of “aging aircraft” was the subject of much discussion during the CAIB investigation. We held a public hearing on this topic and looked in detail at the Shuttle wiring study done by my predecessor at Ames, Harry McDonald. The recommendation to re-certify the Shuttle after 2010 came from all these considerations. My sense is that the Shuttle engineering staff has been sensitized to look for problems, although funding for upgrades was diverted into Return-to-Flight activities and other more pressing concerns.
The good people of the Shuttle will keep working hard on the system as it is, but I doubt there will be significant effort into, e.g., changing out standard insulating tiles for the advanced TUFI variety.
McCurdy: Clever people can lengthen the odds favoring mission success by creating “cultures of safety” among their work teams. NASA officials showed how this works during the Apollo moon program, and the phenomenon has been demonstrated since in a number of high reliability organizations.
Among the practices that allowed NASA’s “culture of safety” to prevail over operational pressures (like schedule) was a widespread acceptance of spaceflight as a very risky endeavor. Managers were committed to the principle that every problem had to be understood before a mission flew, people talked openly, and the government maintained sufficient in-house technical capability so that people in the agency could recognize problems when they occurred. Some set the odds of a catastrophic failure on any lunar landing mission at 30 percent, yet NASA never sustained a single flight fatality through six lunar landings and one exploding oxygen tank. (The odds of completing seven consecutive landings under such conditions were a paltry eight percent.) It was a remarkable achievement.
I was pleased to see these practices resurface in the preparation for the last two Shuttle flights. Hopefully we will never again hear words like “mature…reliable…fully operational…[or] airplane” used in conjunction with the Space Shuttle. If NASA officials treat it like the high-risk, experimental vehicle that it is, they will lengthen their odds of completing the remaining missions without a catastrophic event. The risk will not disappear, but it will be managed in the best possible way.