Space Forum / Shuttle / November 2005

I don't have one. My vision is for a development approach, not a
particular system. It's not particularly original, either; most of these
are alt.space ideas I've gradually come to accept. Nothing I write below
is new but it may sound surprising coming from me.

First look at the desired end state. Viability (at least by my
definition) requires affordability to the point of profitability, such
that continued survival of the system is not subject to the vagaries of
government funding.

Affordability means minimum total cost of ownership. This cost includes
the recurring operations costs and the development cost amortized over
each flight. It follows that to mimimize cost, flight rate must be
maximized - for that matter, as a first approximation, flight rate is
*everything*. The trivial (<10/year) flight rates achieved so far will
not help. You don't really start seeing the costs go down until the
flight rate approaches triple digits. Southwest Airlines has a
maintenance infrastructure comparable to NASA's standing army for the
shuttle, but they're profitable because they keep their airplanes in the
air. If Southwest had a fleet of four 737s and flew them 4-8 times per
year, a 737 flight would cost as much as a shuttle flight, and only the
government could afford to buy the tickets.

In my opinion, it's simply not possible to achieve those kinds of flight
rates with expendable systems. Near-total reusability is a requirement.
The other aspects of system design (number of stages, HTHL vs VTVL vs
VTHL, wings vs no wings, etc) are important only to the extent that they
affect flight rate.

How do you build an orbital vehicle with a flight rate that high? Short
answer is that right now, I don't know - and neither does anyone else,
though some think they do. Attempting to build one now would be like
trying to build a DC-3 in 1914 - or for that matter, attempting the space
shuttle in 1972. It's not that the technologies aren't there, it's that
the existing technologies are too immature and could use more
development.

How to get there from here? We have vehicles that can fly at those flight
rates, though they fall far short of orbital performance (barely
suborbital, actually). And we have vehicles with orbital performance that
fall far short of the required flight rate. We can start with the former
and gradually increase the performance, or we can start with the latter
and gradually increase the flight rate. In my opinion, though the former
approach is not a sure thing, it is far more likely to succeed than the
latter, which is probably a dead end. To stretch a Henry Spencer analogy
a bit, if you've got big dinosaurs and small mammals and you want big
mammals, you're more likely to succeed by growing your mammals than by
evolving your dinosaurs.

There are a number of companies building or planning suborbital vehicles
that could achieve the required flight rate. Most of them are well known
to readers of this group. I won't get into listing my favorites since I
predict that would send the thread into holy wars over particular vehicle
designs. I'd prefer to stay focused on development approaches. The
government could encourage growth in this sector by a variety of
approaches, such as market guarantees and prizes. NASA's Centennial
Challenges has a prize in this area (Suborbital Payload Challenge) but in
my opinion it goes in the wrong direction by eliminating the pilot
requirement and by increasing the altitude requirement rather than the
speed requirement. If it were up to me, I'd issue a prize with the exact
same requirements as the X-Prize except with an additional requirement to
achieve a certain minimum speed (or cover a certain downrange distance
that would in turn require a particular speed). More altitude gets us no
closer to orbit, while more speed will encourage the development of TPS
and propulsion technologies that *will* get us closer to orbit.

A more traditional governmental approach that could also work would be to
start building X-planes again, starting from the level of performance of
the X-15 and gradually increasing performance. In fact, that's the path
the US *was* on with the X-15 before Cold War exigencies diverted us onto
the sidetrack of spam-in-a-can atop converted ICBMs. That way lay the
Dark Side - quicker, more expedient development but lower flight rate and
more expensive operations. True, it got us to the moon by 1969 but was so
expensive that the program was abandoned as soon as its Cold War
political objectives were met. It may get us back to the moon by 2020 but
only with a large governmental commitment that only the most naive think
can be politically sustained for that long.

I grow frustrated with people insisting on learning the wrong lessons
from the space shuttle: that reusable vehicles are necessarily more
expensive than expendables, that crew and cargo must be separated, that
wings are bad. The shuttle didn't fail for any of those reasons. It
failed because NASA attempted to go all the way from the X-15 to an
operational reusable orbital vehicle in one jump, because NASA had too
many diverse customers for the vehicle which resulted in many demanding
performance requirements, and because the development budget was capped
too low. The combination of the above caused NASA to first back off from
total reusability, then having to push existing technology too hard to
meet the performance requirements, then making design tradeoffs that
sacrificed flight rate for lower development cost. Had NASA instead
committed, in the post-Apollo environment, to pick up where the X-15 left
off and gradually work its way to orbit, it may well have taken until the
turn of the century for it to get there - but the result would have been
far more economical.

I would respectfully submit that you're more likely to get to a
sustainable end-state by settling for the next level up in capability
from reusable suborbital vehicles - whether capsules or not.

Kliper is more reusable than Soyuz, so it's at least a baby step in the
right direction. However, it is an inherently low-flight-rate vehicle
using expendable launch vehicles, which means it's ultimately a dead end
- an attempt to evolve a dinosaur rather than grow a mammal. It's not
even the Curtiss Jenny of space, let alone the DC-3 of space.

Perhaps. But if Kliper can act as a 6 person taxi and escape pod and to
a space station, it would be a major advance in how much it costs to
keep people in space since a single vehicle could now support 6 instead
of 3 crewmembers.

If the technology to build a truly reusable vehicle isn't quite there
yet, Kliper is still a step to improve the situation.

Apollo was like a steam locomotive.  Shuttle is like diesel, and so will
Kliper.  At the time diesel locomotives came out and replaced steam
engines, did they just give up improving diesel ones because they
figured that until the technology existed to build TGVs it was pointless
to operate trains ?

I think politicians have watched too much star-trek and expect NASA to
be able to build the Enterprise today and are dispointed that the
Shuttle is so far behind their ideal vehicle. So they call NASA
"incompetant" and force it to return to the steam engine. They should
have tasked NASA to develop a next generation space shuttle, just like
car manufacturers improve their designs every year.

Once you have the basic technologies for a good ship, you can use it to
make mini shuttles without cargo capacity as well as bigger shuttles
with a cargo compartment.  Materials, systems and engines are what
really count and what is missing today. (like a truly reusable heat shield).

One thing and one thing only will open up non govermental human acess
- the development of a viable market.  The fanboys concentrate on the
l33t hardware aspect because the market aspect is seemingly
intractable.

D.