bolts

Is this bolt-issue a show-stopper for the August launch window or will
it be a quick fix??

On 15 Aug 2006 07:36:44 -0700, wrote:

Is this bolt-issue a show-stopper for the August launch window or will
it be a quick fix??

Difficult fix, but probably won't delay launch. I'm not sure why they
should even bother replacing the bolts, which have flown every
Atlantis mission to date.

Brian

Brian Thorn wrote:
I'm not sure why they should even
bother replacing the bolts, which have
flown every Atlantis mission to date.

Atlantis has flown 26 missions to date. The SRBs had flown
successfully 24 times before destroying Challenger. Ignoring a
potentially catastrophic problem on the grounds that you got away with
it before, isn't always a safe bet.

If fixing the bolts became a problem which would incur a delay, I'd be
tempted to just install a net under the antenna. That way if it does
fall, it won't go far. Then fix it properly on landing.

Out of interest, if the antenna had fallen on one of Atlantis's
previous flights, crashing into the engine compartment resulting in
loss of vehicle and crew, would we ever know what happened? Both
Challenger and Columbia had visible smoking guns. But the root cause
of this hypothetical event would be hidden from view. With the antenna
powered down, there would probably be no direct indication that it
failed. First indication would be when engine #3 blew up. Unless they
lucked out on debris recovery from the bottom of the Atlantic, it would
always remain a bit of a mystery.

wrote in message
s.com...
Brian Thorn wrote:
I'm not sure why they should even
bother replacing the bolts, which have
flown every Atlantis mission to date.

Atlantis has flown 26 missions to date. The SRBs had flown
successfully 24 times before destroying Challenger. Ignoring a
potentially catastrophic problem on the grounds that you got away with
it before, isn't always a safe bet.

If fixing the bolts became a problem which would incur a delay, I'd be
tempted to just install a net under the antenna. That way if it does
fall, it won't go far. Then fix it properly on landing.

Of course, we are talking about the main communications and data antennae -
not a good thing to have some off during launch, regardless of whether or
not it causes any damage.

Out of interest, if the antenna had fallen on one of Atlantis's
previous flights, crashing into the engine compartment resulting in
loss of vehicle and crew, would we ever know what happened? Both
Challenger and Columbia had visible smoking guns. But the root cause
of this hypothetical event would be hidden from view. With the antenna
powered down, there would probably be no direct indication that it
failed. First indication would be when engine #3 blew up. Unless they
lucked out on debris recovery from the bottom of the Atlantic, it would
always remain a bit of a mystery.

Well, serious loss of telemetry/communications in the split second before
there were visible signs of a problem should be a huge clue.

George

wrote in news:1155672543.113127.4200@
74g2000cwt.googlegroups.com:

Brian Thorn wrote:
I'm not sure why they should even
bother replacing the bolts, which have
flown every Atlantis mission to date.

Atlantis has flown 26 missions to date. The SRBs had flown
successfully 24 times before destroying Challenger. Ignoring a
potentially catastrophic problem on the grounds that you got away with
it before, isn't always a safe bet.

If fixing the bolts became a problem which would incur a delay, I'd be
tempted to just install a net under the antenna. That way if it does
fall, it won't go far. Then fix it properly on landing.

Out of interest, if the antenna had fallen on one of Atlantis's
previous flights, crashing into the engine compartment resulting in
loss of vehicle and crew, would we ever know what happened?

Probably not. On the other hand, it's highly unlikely the antenna would
make it that far in the first place. On the current flight, the P3/P4 truss
takes up most of the diameter of the bay, so the antenna would most likely
lodge between the truss and the starboard payload bay door. Same for
previous flights - on most of them there was at least one large payload
that would have obstructed a falling antenna from hitting the aft bulkhead.

The biggest concern with the antenna falling is that it could penetrate the
freon coolant loops in the radiators that line the insides of the payload
bay doors. That wouldn't be an immediate catastrophe but it would require
the orbiter to re-enter and land at the first opportunity.

--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
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"George" wrote in
:


wrote in message
s.com...
Brian Thorn wrote:
I'm not sure why they should even
bother replacing the bolts, which have
flown every Atlantis mission to date.

Atlantis has flown 26 missions to date. The SRBs had flown
successfully 24 times before destroying Challenger. Ignoring a
potentially catastrophic problem on the grounds that you got away
with it before, isn't always a safe bet.

If fixing the bolts became a problem which would incur a delay, I'd
be tempted to just install a net under the antenna. That way if it
does fall, it won't go far. Then fix it properly on landing.

Of course, we are talking about the main communications and data
antennae - not a good thing to have some off during launch, regardless
of whether or not it causes any damage.

Actually, the Ku-band antenna is just the high data rate system. The
primary system is S-band, with its own separate antennas. There is also a
UHF system for voice.

Out of interest, if the antenna had fallen on one of Atlantis's
previous flights, crashing into the engine compartment resulting in
loss of vehicle and crew, would we ever know what happened? Both
Challenger and Columbia had visible smoking guns. But the root cause
of this hypothetical event would be hidden from view. With the
antenna powered down, there would probably be no direct indication
that it failed. First indication would be when engine #3 blew up.
Unless they lucked out on debris recovery from the bottom of the
Atlantic, it would always remain a bit of a mystery.

Well, serious loss of telemetry/communications in the split second
before there were visible signs of a problem should be a huge clue.

Only if the antenna fell off in orbit. The Ku system is not used during
ascent or entry.


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

"Jorge R. Frank" wrote in message
...
wrote in news:1155672543.113127.4200@

The biggest concern with the antenna falling is that it could penetrate
the
freon coolant loops in the radiators that line the insides of the payload
bay doors. That wouldn't be an immediate catastrophe but it would require
the orbiter to re-enter and land at the first opportunity.

Am I correct in remembering each loop (well "door") can be shut off
independently?



--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
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"Greg D. Moore \(Strider\)" wrote in
nk.net:


"Jorge R. Frank" wrote in message
...
wrote in news:1155672543.113127.4200@

The biggest concern with the antenna falling is that it could
penetrate
the
freon coolant loops in the radiators that line the insides of the
payload bay doors. That wouldn't be an immediate catastrophe but it
would require the orbiter to re-enter and land at the first
opportunity.

Am I correct in remembering each loop (well "door") can be shut off
independently?

That's right. There are two freon loops, one through each door. There are
also radiator isolation valves on each loop to help stop a leak (though
that won't help the cooling situation).


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

"Jorge R. Frank" wrote in message
...

That's right. There are two freon loops, one through each door. There are
also radiator isolation valves on each loop to help stop a leak (though
that won't help the cooling situation).

Right, but I was thinking more the case where you couuld in theory isolate a
loop long enough that you're more "hurried" than absolutely rushed.




--
JRF

Reply-to address spam-proofed - to reply by E-mail,
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wrote:
Ignoring a
potentially catastrophic problem on the grounds that you got away with
it before, isn't always a safe bet.

On the other hand, replacing something that's been working for decades,
in a hurry, on the launch pad, isn't always a safe bet...

Mark