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Jeff Findley wrote:

From what I can tell, Dragon will be
grappled by the SSRMS and berthed to a CBM port on an MPLM. So Dragon
has to hold still enough to be grabbed.

This is the same sort of operation that the Japanese H-2 Transfer
Vehicle (HTV) performed back in 2009, so it's not going to be a "first".
But if it's successful, this should be huge news for the US spacecraft
industry.

Errr, why? Other than the arm being on the passive vehicle rather than
the active one, surely it's no different to any of the Hubble servicing
missions or any other time the shuttle went up to park next to something
else and grab it with the arm.

Because with Hubble, the shuttle crew controlled both the rendezvous
*and* the grapple. Hubble has no reaction control system. It can only
control its orientation (which it does with great precision).

With Dragon, there is no crew on board to control the rendezvous.
Automated rendezvous of this type isn't trivial. Remember the
Progress/Mir collision? I'm sure no one wants a repeat of that accident
with ISS.

Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011