"Dholmes" wrote:

2) Using three launches have nothing to do with rocket capabilities. The
heavy versions of both the Delta and Atlas could launch a Big Gemini with
lots of cargo mass left over totaling more people and more cargo then the
shuttle. It has to do with reducing risks even though it raises costs.
...
4) If you are using 3 OSP flights to replace a shuttle flight and you
replace at least 4 shuttle flights a year that totals 12 not 4 or 8. If
you
replace 6 shuttle flights then you have 18 flights.

I think we also have to consider what the future needs will be. After ISS is
assembled, would there be a need for launching crews *and* payloads
together? For satellites, space telescopes, etc. there is a need for a
*single* launch. For crew rotations carrying a small amount of payload
there is need for a *single* launch. I find this comparison in Rand's
column off target.

Also, there is some value in having a crewed vehicle that is operationally
simpler, has fewer crit 1 items, and has viable abort modes that cover a far
wider range of the flight envelope than is currently available with shuttle.

There are a few companies out there now that are working hard trying to make
an attempt at a short, suborbital flight (the links that Rand provided in
his column when referring to private ventures: "having its [NASA] high-cost
myths exposed as private entities start to show the way to affordable and
safe human spaceflight"). As much as I find Scaled Composite's current
endeavor fascinating to follow, let's keep in mind that there is a big
difference between what it takes to go from 2,000 mph in a suborbital arc to
17,500 mph and LEO - the ideal energy required (per pound) scales roughly
with the square of the velocity. I also want to see safe and affordable
routine access to space become available, and I am curious as to just how
cheap and safe Rand thinks a private company could do it, compared to the
current way (or proposed future, as with OSP) it is being done. How much
should it cost a private enterprise to develop and test a four person space
transportation vehicle? How much should it cost, per flight, to operate? In
other words, how far off the mark are we, now?

Jon