On Fri, 11 May 2007 16:31:12 GMT, in a place far, far away, "Greg D.
Moore \(Strider\)" made the phosphor
on my monitor glow in such a way as to indicate that:

Rand Simberg wrote:
When you see all of the ways that the LAS can cause a bad day to a
nominal mission, I would seriously question its value on Orion.


We've never had a fatal accident to a crew caused by one, and one Soyuz
launch where it saved a crew.

The sample space is far too small to draw many conclusions from that.

Hmm. Define 'far to small'. My understanding is that statistically
anything over 100 samples is "reasonable" and we have what, about 150?

No, not for our vehicles. Only if you include the Soviets/Russians.
I interpreted Pat's "we" to mean the US. The Russians have a
different design, and I can't say what kind of failure modes it has.

Yeah, I was counting the Soviet/Russian design.

Of course actually one could argue we have over 250 samples if you include
systems without a LES. And most likely in at least one of those it would
have saved the crew.

I wasn't making a generic comment about LES. I was talking
specifically about Orion and its launcher. It's questionable whether
the LAS adds, or removes risk from the system, when it has so many
failure modes that can occur on a nominal day, and when it's been a
long time since we had a failure of a modern launcher that would have
required it. Remember, as designed, it's really only needed to get
away from a suddenly exploding launch vehicle, or for a pad abort, not
for a lack of thrust, or loss of control, which is the predominant
failure mode for launchers. It seems like an exceedingly unlikely
failure scenario for the Porklauncher.

I think that it's simply politically incorrect to not have one. No
one at NASA wants to take the slightest chance of having to explain to
Congress why we lost a crew because we once again left out an escape
system. But I'm not sure that they realize that they may have just as
great, or greater a chance of having to explain to Congress why the
(heavy and expensive, every flight) escape system killed the crew on
an otherwise nominal mission.