Earth to NASA: WTF?

I simply cannot fathom why the folks at NASA have decided not to repair the damaged tiles on Endeavour. As William Harwood wrote today:

"Late Thursday, mission managers decided test data and analysis proved Endeavour could safely return to Earth as is. A tile repair spacewalk was ruled out and the astronauts were told to press ahead with the station assembly EVA instead.

The damage assessment brought back memories of an internal debate after the shuttle Columbia's launching in 2003. In that case, a relatively limited study was carried out to determine the possible damage caused by a large piece of foam debris that hit the underside of the shuttle's left wing during launch. NASA's Mission Management Team accepted a hurried analysis by a small group of engineers and concluded Columbia could safely re-enter as is even though the actual impact site could not be seen in launch imagery.

The analysis was deeply flawed. Equally troubling in hindsight, the Mission Management Team did not hear, or take seriously, concerns from lower-level engineers who were not satisfied with the review. As it turned out, what NASA managers believed was relatively minor damage to heat-shield tiles was, in fact, a 4- to 6-inch hole in the leading edge of Columbia's left wing. Sixteen minutes from touchdown, the left wing failed, the spacecraft broke apart and all seven crew members were killed. "

via Spaceflight Now

Here we are again, 4 1/2 years later, and NASA has another damaged shuttle on orbit. The differences in this case are stunning:

1. NASA knows for certain there has been damage


2. NASA spent years developing and testing various damage control methods


3. The newly-developed repair materials are onboard Endeavour


4. The Endeavour crew have the skills, materials, time, and consumables needed to effect repairs

But even given the facts above, NASA mission planners have decided that the risk in an unplanned EVA is greater than that in landing the orbiter with damaged tiles in a vulnerable location.

But a Nobel Prize-winning physicist who served on the Columbia investigation board 4 years ago, Douglas Osheroff, questioned NASA's hesitancy to perform the repairs since they "can only increase their chances of making it down." "I don't see why NASA is going to invent a fix and not use it," Osheroff told the AP. He added: "This attitude of, 'It looks like it's OK, let's not do anything about it,' it seems like the Columbia NASA."

About those damaged tiles-- NASA reports that the gouge between the two tiles goes all the way to the aluminum skin underneath, approximately 2 inches deep. I am not an engineer, but I'm sure there was a really good reason to make the tiles that thick, given the added cost in weight, fuel, & decreased payload for every gram of extra mass. It just doesn't seem reasonable that a hole in this surface doesn't pose a threat to the orbiter.

Let's hope for the sake of the crew, their families, and the continued human exploration of space that they are right.