Hey everyone,
Here is a link to a Sandia newsletter with some details from their work
after Columbia:
https://www.sandia.gov/LabNews/LN09-05-03/labnews09-05-03.pdf
Good quote that captures what thinking was during the post-disaster
investigation:
“After our prediction that the foam would penetrate the RCC, we faced a
very skeptical community,” Tom says. “We had to convince ourselves and our
colleagues that we were correct through the use of materials testing and
many confirmatory simulations."
On Fri, Mar 27, 2020 at 3:01 PM Rand Simberg <simberg@xxxxxxxxxxxxxxx>
wrote:
This is one of the arguments made for a U.S. Space Guard:
https://www.thenewatlantis.com/publications/proposing-a-coast-guard-for-space
On 3/27/20 11:55 AM, Henry Spencer wrote:
On Thu, 26 Mar 2020, ken mason wrote:
I know the official story Bill but It is common knowledge such
imagery was used in a earlier mission were tiles were dislodged from
the aft end of the orbiter, can't remember the mission but it's on
record. So it would be ludicrous that they wouldn't utilize such
assets again.
Note what Bill said: yes, such imaging was done on other occasions
(the missing-tiles incident you're thinking of was probably STS-1),
but this time, the risk was thought slight and it didn't seem worth
the hassles of trying to talk the spooks into doing short-notice
imaging. These weren't *NASA* assets, remember: it meant asking for
a big favor from some difficult people.
I also remember the chatter about preparing Atlantis for a
rescue mission... Why would such discussions of a rescue take place
if no damage wasn't plausible?
The discussions took place because some people were worried,
especially early on. But a careful assessment concluded -- correctly!
-- that the falling foam couldn't plausibly do dangerous damage to the
tiles. And damage to the carbon-carbon panels was not seriously
considered, partly because nobody really understood that old,
weathered carbon-carbon wasn't nearly as durable as the freshly-made
stuff. Not everybody was entirely reassured, but you can't
automatically push the panic button because of that -- somebody has to
make a judgement call.
By the way, it's by no means certain that spysat imaging -- with
limited resolution, possibly some motion blur, and probably
less-than-ideal lighting and background -- would have clearly showed a
hole in a *black* surface. Doing that imaging might simply have
satisfied everyone that there was nothing to worry about.
The real problem was that NASA shuttle ops had fallen back into the
same trap that caused Challenger: "we got away with it a few times so
it must be okay". This was not the first time there'd been falling
foam, but the matter wasn't being treated as urgent.
This was not some random aberration, but a problem built into the
system, which would have caused trouble in some other way eventually
if it hadn't that time: a fragile, semi-experimental vehicle was
being treated as an operational transport.
NASA had never been given the money and resources and time to properly
develop and test an operational transport (and in any case, NASA
didn't really know how), but NASA needed an operational transport so
the Shuttle was decreed to be one. (Hint: truly experimental
vehicles carry no people except test pilots, and no payloads except
test instrumentation.) And so, despite pious pronouncements about how
it would always be an experimental vehicle, there was constant
pressure to *treat* it as an operational transport, well understood
and unlikely to have dangerous problems. After Columbia, a fellow
who'd been involved in Shuttle development told me that on watching
the Mission Control reentry video, he was shocked at how *unconcerned*
people seemed as problems developed. They thought of it as an
operational vehicle.
Oh, and despite considerable effort after Columbia was lost, the foam
problem was never fully cured: there was falling foam on most of the
post-Columbia flights too, right up to the very last.
Don't be too sure these problems have gone away -- think about SLS and
Orion. Even with Commercial Crew, there's still a major flaw in the
system: NASA is simultaneously the customer and the safety authority.
It's much better if safety assessment and approval is done by people
who *don't* have a vested interest in meeting schedules and budgets.
Henry