In article om,
says...

On 12-10-08 14:38, Jeff Findley wrote:

Considering the same launch carried Orbcomm?s O2G-1 communications
satellite (313 lb), I'd say it's lightly loaded.


Is it possible that when you combine Progress, ATV, HTV and now Dragon,
there is more uplift capacity than needed ?

I would think that the ISS partners will find uses for the "excess"
capacity, so it won't truly be "excess" in the long run.

BTW, one of the NASA officials had mentioned that with the last shuttle
flights, they brought a huge amount of equipment for experiments that
are scheduled over a long period of time so if the station hasn't
finished with those experiments yet, there won't be much room/time to
bring new ones.

Dragon will be extremely useful for its ability to return experimental
results and equipment to earth. No other spacecraft currently in use
for ISS cargo resupply has that ability.

Another possibility is that because Dragon is new, it isn't yet part
of
the critical path so much of the planning scheduled the "real" cargo
between ATV/Progress/HTV.

It would be prudent to use it, at least initially, to deliver cargo
which could be easily replaced should the mission fail. I would expect
this level of caution to extend to Orbital's Cygnus resupply vessel as
well.

Jeff
--
"the perennial claim that hypersonic airbreathing propulsion would
magically make space launch cheaper is nonsense -- LOX is much cheaper
than advanced airbreathing engines, and so are the tanks to put it in
and the extra thrust to carry it." - Henry Spencer