Brian Thorn wrote:
I'm still not convinced we haven't already seen the last Shuttle
flight, but in any case isn't the US position that it will use CEV to
go to/from ISS after Shuttle?

What is it about ISS that precludes its operation without Shuttle?

The ability to send new racks full of equipment up and back down.

The ability to bring back down failed devices (such as the failed CMG)
for a post mortem. Oh, and consider that first the first time, the
Russians will be able to look at an Elektron unit that failed in space
and really study it. It has never been possible on MIR to bring such
equipment back to find out exactly why it would fail. (The failed
Elektron came back in te MPLM with Discovery).


In a context where the ISS is used to test/debug systems that would be
used for long duration trips, the ability to bring back large pieces of
equipment for full analysis on earth is very important.

The USA experience on MIR showed that having large hatches and large
capacity to bring stuff not only up but also down was very valuable.
This is why you have CBM hatches on the US station, and why you have MPLMs.


The Japanese may be able to send HTV up which may replace some of the
MPLM functionlality, but it won't be able to return stuff to earth.