Re: Japans Moon Ambitions - They're KIDDING, Right ?

edkyle99_at_hotmail.com
Date: 03/03/05 

Date: 2 Mar 2005 17:43:20 -0800

Rand Simberg wrote:
> On 2 Mar 2005 07:19:11 -0800, in a place far, far away,
> edkyle99@hotmail.com made the phosphor on my monitor glow in such a
> way as to indicate that:
>
> > non-hardware
> >failure modes like bad software loads or bad ground
> >processing steps (e.g. forgetting to remove a piece
> >of tape from a connector pair that is supposed to
> >separate - something that really happened) now account
> >for more failure modes than the hardware - resulting
> >in the total predicted failure rate for these newest
> >of rockets being roughly 2%.
>
> That's not a technology issue, per se. It's a design problem.
>

In its Atlas V mission planner guide, Lockheed Martin discusses
two types of reliability prediction. One type is design
(hardware) reliability. The other type, mission reliability,
incorporates problems that occur during manufacturing, assembly,
test, and system integration. These are not design problems,
but failure to implement the design. As the numbers show,
non-design problems are expected to cause more failures than
design problems.

"Table A.4-1 Typical Atlas V Reliability
 Predictions-GTO Mission Profile, Atlas V

Atlas V Design Mission
Type Reliability Reliability

AV-401 0.9954 0.9865
AV-531 0.9930 0.9826"

>
> That's not reality. Well, the Shuttle reliability is reality, but
> that doesn't mean that space transports have to be intrinsically
> unreliable, even with current technology. It just means that they
> have to be better designed and tested.
>

I'm not sure you can test much better than
they already do at the world's space centers,
at least not as long as humans are involved
in the process. Real improvement might only
come from adding fault tolerance and true
redundancy (engine-out capability, for example)
into the designs. Higher flight rates would
also help. But these things take gobs of
money, and no such money will pour into space
unless there is a sea-change in the business
- something like XM Satellite or Sirius
reporting a massive profit - that leads to
a substantial increase in the number of space
launches.
 
 - Ed Kyle

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