In article m,
says...

Snidely wrote:

Even better,
http://www.nasa.gov/mission_pages/station/multimedia/gallery/iss031e070745.html


Interesting that SpaceX chose to have the grapple fixture behind a trap
door instead of affixed externally.

Seems to introduce a failure mode if the trap door doesn't open
properly. (and I suspect presents structural challenges to have that
door be able to haul the whole craft around when the arm wants to move
it.) Even worse, if the door doesn't close, re-entry wouldn't be
possible (a bit like shuttle's cargo bay doors).


Wouldn't it have been easier to put the grapple fixture on the service
side of the craft instead of having it is on the re-entry module ?

It would have been easier, but then it would burn up on re-entry after
every mission. From what I understand, SpaceX has put *a lot* of
hardware into the capsule that has traditionally been in a disposable
service module precisely because they plan to reuse the hardware.

In this case, perhaps NASA wants a "new capsule" for each ISS mission,
but does that necessarily mean it wants a new grapple fixture for each
mission, or would they let SpaceX use one already flown on another
capsule? Seems to be a question that only NASA and SpaceX can answer.
Furthermore, the answer may change over time if someone at NASA realizes
that building a brand new grapple fixture for every flight is becoming
expensive.

Jeff
--
" Ares 1 is a prime example of the fact that NASA just can't get it
up anymore... and when they can, it doesn't stay up long. "
- tinker