MSNBC (JimO) on value of 'big door' on ISS

In article , John Doe wrote:
That hatch (CBM) is about to get very useless when the shuttle is
retired and the whole concept of MPLM becomes moot, unless the Japanese
actually develop and produce their HTV.

Or unless either the CEV or one of the COTS commercial vehicles berths to
a CBM instead of docking. Which several of the COTS designs do; I'm not
sure about the Continued Employment Vehicle. (For a while it was going to
use a new lightweight docking interface, if I recall correctly, but that
has since been canceled.) That's what the shuttle *should* have done,
instead of using the CBM interface only for the separate MPLMs.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

On Sat, 8 Jul 2006 06:10:29 GMT, in a place far, far away,
(Henry Spencer) made the phosphor on my monitor
glow in such a way as to indicate that:

In article , John Doe wrote:
That hatch (CBM) is about to get very useless when the shuttle is
retired and the whole concept of MPLM becomes moot, unless the Japanese
actually develop and produce their HTV.

Or unless either the CEV or one of the COTS commercial vehicles berths to
a CBM instead of docking. Which several of the COTS designs do; I'm not
sure about the Continued Employment Vehicle. (For a while it was going to
use a new lightweight docking interface, if I recall correctly, but that
has since been canceled.)

They're still trading LIDS and APAS, and dual capability.

On Sat, 8 Jul 2006 06:10:29 GMT, (Henry Spencer)
wrote:


Or unless either the CEV or one of the COTS commercial vehicles berths to
a CBM instead of docking. Which several of the COTS designs do; I'm not
sure about the Continued Employment Vehicle. (For a while it was going to
use a new lightweight docking interface, if I recall correctly, but that
has since been canceled.)

Isn't the lightweight docking system planned for the "Block II' (or
whatever the lunar version is called) to save weight? Block I is
supposed to be as much off-the-shelf as NASA can get, to reduce
development time and cost.

That's what the shuttle *should* have done,
instead of using the CBM interface only for the separate MPLMs.

Why? There doesn't seem to be much room in the Shuttle's crew cabin
for Station racks, which means they'd still have to use the MPLMs to
haul them back and forth. In that case, why bother with the expense of
a new Shuttle airlock, new shuttle docking tunnels, etc., when you can
just berth the MPLM and move cargo directly? The only thing Shuttle
docking at a CBM would help would be with the Spacehab used as a cargo
hauler (i.e., STS-116) but that's always been secondary to MPLM
anyway.

Brian

In article ,
Brian Thorn wrote:
That's what the shuttle *should* have done,
instead of using the CBM interface only for the separate MPLMs.

Why? There doesn't seem to be much room in the Shuttle's crew cabin
for Station racks, which means they'd still have to use the MPLMs to
haul them back and forth.

For any substantial amount of cargo, you need to put a cargo carrier of
some kind in the cargo bay. But it, the connecting tunnels, the docking
assembly, etc., could all have been designed with the larger hatch from
the start.

In fact, if dim memory serves, that *was* the plan for SSF: there was to
be no docking, only berthing(*), and the CBM was *the* interface.

(* For those having trouble remembering the difference: with docking you
slam into the station, preferably in a more-or-less controlled manner :-),
while with berthing, you stop a few meters away, and the station arm grabs
you and maneuvers you in, under positive control at whatever speed is
convenient. )

In that case, why bother with the expense of
a new Shuttle airlock, new shuttle docking tunnels, etc., when you can
just berth the MPLM and move cargo directly?

There's *some* advantage in moving a cargo module over to the station,
because it permits loading and unloading to be done at leisure during
normal station operations, instead of in a brief frenzy during a shuttle
visit. But it's still sensible to use the big hatch in all new hardware,
for the extra flexibility.

Turn it around: given that at the beginning of the planning, there *was*
no previous shuttle docking tunnel etc. -- the shuttle had never had an
orbital destination that was pressurized -- why would you bother using
anything but the big hatch?
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |

(Henry Spencer) wrote in
:

In article ,
Brian Thorn wrote:
That's what the shuttle *should* have done,
instead of using the CBM interface only for the separate MPLMs.

Why? There doesn't seem to be much room in the Shuttle's crew cabin
for Station racks, which means they'd still have to use the MPLMs to
haul them back and forth.

For any substantial amount of cargo, you need to put a cargo carrier
of some kind in the cargo bay. But it, the connecting tunnels, the
docking assembly, etc., could all have been designed with the larger
hatch from the start.

In fact, if dim memory serves, that *was* the plan for SSF: there was
to be no docking, only berthing(*), and the CBM was *the* interface.

And let us not forget why that changed: for the Shuttle-Mir program, NASA
needed to adopt the Russian APAS-89 docking system. Once that was done, it
was cheaper to just keep using that for ISS rather than the still-
undeveloped SSF shuttle berthing interface.

It looked like a good decision back when it looked like APAS-89 was going
to become an ISS universal standard for Soyuz, Progress, and ATV as well.
After the Russians abandoned APAS-89 and reverted to probe-and-drogue it
looks markedly less so.

--
JRF

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check "Organization" (I am not assimilated) and
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On Sun, 9 Jul 2006 19:06:13 -0500, Henry Spencer wrote
(in article ):


In fact, if dim memory serves, that *was* the plan for SSF: there was to be
no docking, only berthing(*), and the CBM was *the* interface.

(* For those having trouble remembering the difference: with docking you
slam into the station, preferably in a more-or-less controlled manner :-),
while with berthing, you stop a few meters away, and the station arm grabs
you and maneuvers you in, under positive control at whatever speed is
convenient. )

SSF was baselined for CBMs between all pressurized station segments and
two PMAs for orbiter docking from at least Phase B forward if not Phase
A. So, as far back as at least 1990 there was no plan to use CBMs for
physically connecting an orbiter to the station proper. Plans were
ALWAYS to use PLMs (Pressurized Logistics Modules) and later MPLMs
(originally denoting Mini-PLM) for bulk and outsized cargo transfer.

--
Herb

"Everything is controlled by a small evil group to which,
unfortunately, no one we know belongs."
~Anonymous