"Ed" wrote in message
oups.com...
kert wrote:
Joe Strout wrote:
In article . com,
"kert" wrote:

So why exactly is launching six astronauts in one vehicle better than
launching three astronauts in two vehicles at the same time ? Since
when has putting all eggs in one basket, or launcher in this case,
become a wise practice ?

I think the assumption is that one basket is dramatically cheaper than
two.

Whether that assumption is true, I don't know, though I can well
imagine
it might be. One way, you get economies of scale in the launcher
itself, though the other way, you get some economies of scale in the
launch rate. I can't guess which would dominate.

No, not only launch rate. With smaller vehicle you can (potentially)
get flexibility, economic savings and redundancy in picking the
launcher itself as well.
IOW larger vehicle makes sense if you look at given vehicle/launcher
combination in isolation, ignoring the existing launch market.

-kert

being able to put everthing up in one throw has been the the norm for
the last several decades, during the end of the the gemini program the
plan was to use several launches to get to the moon.

if you used the gemini big transport 2 crew + 7 passengers, (16,000 kg
+ 4,000 kg launch escape tower) you would need the Delta iv (cost 140
mill '99) you would still have 4,000 kg of unused cargo to iss.
if you where using the origianl gemini a crew of 2, (2,000 kg) using
the same atlas v 401 (cost 77 mill '98) you would get 2 to iss and
10,000 kg of unused cargo to iss.

while one would assume that with the gemini big the unused cargo mass
could be stowed aboard, while with the original gemini, anouther modual
would be required, possibly something simular to the shuttles extenetd
duration or fuel pallets could make use of the extra avaliable launch
mass. but that doesn't address the problems of where to park or
transfer systems.
if you where going to the moon then you need to fuel and resupply
launches for the cev as well.


a kg/dollar comaprison

4 - atlas v 401 - 48,000 kg - 308 million, just for boosters
2 - delta iv - 46,000 kg - 280 million, just for boosters


It'll be interesting to see if those cost numbers stay the same or change,
once (if) the United Launch Alliance merges the two launch vehicle lines
into one company.