I was referring to the Thermal Protection System in terms of damage. Since Columbia, each flight has a cleaner and cleaner TPS and they have gotten quite good at detecting debris and damage. I don't believe we'd have another failure related to the TPS again in the program.
Just like since Challenger, we haven't had any problems with the SRB's.
Challenger truly was disgusting though, there was a lot of negligence and poor management that led to the disaster. Columbia was a bit different, it was a terrible accident and while in hindsight, there were warning signs, there were few that actually thought there was even the potential for an issue. This by no means makes it acceptable, however.
Since then, numerous improvements have been made to the ET design and monitoring of the TPS. The chance of damage to the TPS is drastically reduced, and if any such damage were to occur (as very small damage has), it is easily found and monitored while its impact is assessed. If there is anything that presents a risk to the crew, a LON mission or Soyuz rescue will be used.
But what else can you do? You have to work as hard as you can to ensure safety (which in the case of the oil spill was not done). But in the end, there will always be some risk. You can't eliminate it altogether, you can only reduce it to the smallest extent possible.
This is the goal with any vehicle. Yes, the TPS design of a capsule based system would be advantageous. But that doesn't inherently make it safer. There are still many other factors with the vehicle and launcher that could lead to disaster. Sure, the TPS might not be the failure, but who's to say there may not be one elsewhere?
With the shuttle we have one important thing that any new vehicle will not have - experience. There is data from over a hundred missions that has helped increase the understanding of how the vehicle works. Lessons have been learned from the disasters and other hiccups and are applied thereafter. While a new vehicle may be safer eventually, one cannot say until it has been flown a significant number of times.
The shuttle has approximately the same fatality rate as the Soyuz, the only other spacecraft with a significant operational history.
There are inherent flaws with the shuttle's design, yes. But that can be said about every spacecraft, heck, every vehicle.
The shuttle was designed to meet a set of requirements (DoD) that were largely dropped and changed over time. It is inefficient for what it is being used for, thus, it is time for a replacement. Yet since none is available, it is a shame to retire our only operational spacecraft, one at which we have significant experience flying and are doing so successfully, without knowing what will come next.
NASA Administrator Griffin also pushed flying people on the Ares I vehicle. Possibly the worst designed launcher in history. That is his personal opinion and I do not agree with it at all.
Griffin was an awful manager. One can also reasonably suspect that the real reason Griffin wanted the shuttle retired was to ensure that funds were available to his Ares I launcher. He claimed it wasn't due to expense, but with the safety argument more compelling, I have to wonder.
I'd rather have the evaluation of John Shannon, Bill Gerstenmaier, Mike Moses, Mike Leinbach, etc. These guys are the ones that work on the vehicles daily, and they are fantastic engineers. I think they are the ones that are best able to make that assessment, especially as they are not involved with the politics as well.
Comparing MER to shuttle is like comparing apples to oranges. I am a fan of both but looking at the architectures and the requirements, comparing costs is difficult.
Now, I believe that STS-135 (additional mission for Atlantis) would be very good. Not because I like the shuttle or whatever, but because it would be very beneficial to the ISS. The ISS was designed to be serviced for its entire lifetime by the shuttle, it is now clear that is not going to happen. Having that extra mission will be of great benefit to the ISS.
Correct. And the concept of the main engines on the tank to separate the payload from the launcher is definitely a good one. Allows for an expandable architecture more easily than the shuttle (that being one of their goals). Plus having the SSME attached to the orbiter decreases your allocatable downmass...although you do get the engine back.
