🚀 go-pugleaf

In <1993Jan7.034841.19216@ptdcs2.intel.com> greason@ptdcs2.intel.com (Jeff Greason ~) writes:

>While your arguments about availability are sound in principle, they
>ignore the element of risk.  Shuttle availability has a long time window
>to availability, in months, but it is reasonably likely to be available
>when predicted to be, with some error margin <error margin because the
>schedule is ill-controlled, only "reasonably likely" because of the
>possiblity of another crippling accident shutting the STS down>

It wouldn't take a crippling accident to ground the Shuttle fleet
for several months.  History has shown that.  It could be something
as simple as a crane running into the side of the orbiter stack
or a problem with the APUs.  

If an orbiter hits one of the wild pigs, which live just yards from
the Shuttle runway,  it could put the vehicle out of action for more
than a year, resulting in delays or cancellations of many payloads.

And when (not if -- given enough Shuttle missions, it will happen)
there is another fatal accident, Congress and the White House will
shut the program down for at least another two years *if not permanently*.

If assured access to space was a concern, NASA would being buying 
Soyuz spacecraft/launchers right now, just to hedge its bet.


>One point that gets lost is that while DC-X is "bent metal" and will 
>solidly demonstrate the "quick turn" aspects of a launch vehicle (or 
>not), it will NOT demonstrate the key SSTO capability of a vehicle with 
>the extremely small "dry mass" necessary to make SSTO work

The "extreme mass ratio" is an aerospace legend.  We've been
building vehicles with similar mass ratios for the last 30
years.  The Shuttle external tank has the right mass.  So
did the Saturn S-IVB stage.


>This is a fairly long-winded lead in to say that no matter how great DC
>may be, you cannot stop shuttle flights before an operational DC capability
>exists, 

But we will, the first time someone whose nameplate says "astronaut"
gets killed.