Dholmes wrote:

"Bob Martin" wrote in message
...
I'm interested in seeing what you guys would come up with if you were
writing the requirements for the OSP. Any takers?

I am kind of torn between large and small.

A simple capsule would require over a dozen launches a year giving some
needed volume.

A larger space plane would need only 3 or 4 launches a year but help to
develop heavy lift.

A capsule should be both cheap and quick to develop.

A large space plane while more expensive to develop has better follow on
when a reusable first stage is developed.


Most of those questions are the same ones we asked at the beginning
of shuttle development.

We ended up settling for a system that was (allegedly) cheaper to
develop, but more expensive to operate. Not that NASA didn't want the
TSTO all flyback stage designs that would have been the reverse, but it
soon became clear that Congress wouldn't pony up the higher up-front
costs, and there was much controversy over what the expected traffic
models were most realistic. The more traffic to orbit you expect, the
more a vehicle with lower operating costs (in spite of higher
development costs) make sense.

However, one of the opposing arguments was that a Mars mission would
be one of the projects for which this shuttle would be used for (NASA
would still be only user, after all), and this was a way of pulling the
rug from beneath the idea.

Similarly, you have to ask what an OSP will be used for. Mostly ISS
servicing? Do you dare suggest it might have the capacity of also
supporting another large manned project? (Moon/Mars/Near Earth Asteroid,
take your pick) Some people still don't want to hear that....

And are its payload capacity (volume and weight) and operating costs
such that there might be a commercial interest? NASA has long said it
wants a vehicle that is a convergence of the two. Others say (and I'm
strongly inclined to agree) that the needs are so different that such a
one-size-fits-all convergence may not be possible.