Spacehab vs MPLM

What's the difference in structure, function and use
between the Spacehab and the MPLM?

Sir Frederick wrote in
:

What's the difference in structure, function and use
between the Spacehab and the MPLM?

The Spacehab is designed to stay in the shuttle payload bay, has extensive
power capabilities to run internal payloads, and has a small tunnel leading
to the ODS.

The MPLM is designed to be berthed to ISS, has more limited capability to
power internal payloads, and has a large square hatch leading to ISS.

--
JRF

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On Sun, 10 Dec 2006 21:59:21 -0600, "Jorge R. Frank" wrote:

Sir Frederick wrote in
:

What's the difference in structure, function and use
between the Spacehab and the MPLM?

The Spacehab is designed to stay in the shuttle payload bay, has extensive
power capabilities to run internal payloads, and has a small tunnel leading
to the ODS.

The MPLM is designed to be berthed to ISS, has more limited capability to
power internal payloads, and has a large square hatch leading to ISS.

Thanks. So why the Spacehab this flight, when the MPLM
in the past?

Sir Frederick wrote:

On Sun, 10 Dec 2006 21:59:21 -0600, "Jorge R. Frank" wrote:

Sir Frederick wrote in
m:

What's the difference in structure, function and use
between the Spacehab and the MPLM?

The Spacehab is designed to stay in the shuttle payload bay, has extensive
power capabilities to run internal payloads, and has a small tunnel leading
to the ODS.

The MPLM is designed to be berthed to ISS, has more limited capability to
power internal payloads, and has a large square hatch leading to ISS.

Thanks. So why the Spacehab this flight, when the MPLM
in the past?

Jorge as a bit unclear on the differences - MPLM's large squarge hatch
allows rack sized components to be moved into the ISS, while
Spacehab's narrow hatch limits cargo to (IIRC) about the size of your
average PC. MPLM must be removed from the Shuttle's cargo bay and
berthed to the ISS directly, while you have acess from Spacehab as
soon as the Shuttle/ISS hatch is open. (MPLM is also, IIRC, larger
and heavier than Spacehab.)

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Sir Frederick wrote:
Thanks. So why the Spacehab this flight, when the MPLM
in the past?

MPLM takes up a large part of the Shuttle's cargo bay. Spacehab takes up
less space, so there is more space for cargo.

The last flight of Columbia had a large spacehab that was outfitted as a
lab with lost of research equipment inside.

But for station-bound flights, Spacehab brings no special functionality
compared to existing lockers inside the shuttle because everything must fit
through the narrow hatch between shuttle and station.

Also, in the past, Spacehab brought certain restrictions when EVAs were
performed from the shuttle. The shuttle was isolated from the station so it
could lower its air pressure, AND the spacehab was isolated from the
shuttle because the tunnel between the two was also the airlock. So ducing
periods of EVAs, the transfer of goods could not proceed.

With an MPLM, the unit was transfered to the station with the arms, and
while the shuttle was isolated to conduct its EVAs, the station crew had
access to the MPLM to move the supplies out of the MPLM (and stuff destined
back to earth into the MPLM).

However, with the station's airlock now used, the shuttle is no longer
isolated for days during EVAs and this is no longer an issue,



I think the logic is that when the Shuttle is bringing up a station module
that is too large to co-exist with an MPLM, but leaves enough space to fit
a Spacehab. The spacehab is then loaded with various sundry supplies for
the inside of the station.


I think that there are also contractual issues between NASA and Spacehab
Inc where NASA committed to a certain number of flights using Spacehab.


Personally, with the number of shuttle flights finite, wouldn't it be
better to see NASA dump spacehab flights and replace spacehab with some of
the smaller modules such as cupolla , perhaps bring back EAS ?

I realise that in the original assembly plan, Spacehabs were planned as
fillers because those smaller modules would not have been delivered to KSC
yet, but in the current schedule, everything is sitting in a wharehouse
waiting to be launched. So why not put a few smaller modules in the cargo
bay instead of a spacehab ?

On Mon, 11 Dec 2006 02:31:19 -0500, John Doe wrote:

Sir Frederick wrote:
Thanks. So why the Spacehab this flight, when the MPLM
in the past?

MPLM takes up a large part of the Shuttle's cargo bay. Spacehab takes up
less space, so there is more space for cargo.

The last flight of Columbia had a large spacehab that was outfitted as a
lab with lost of research equipment inside.

But for station-bound flights, Spacehab brings no special functionality
compared to existing lockers inside the shuttle because everything must fit
through the narrow hatch between shuttle and station.

Also, in the past, Spacehab brought certain restrictions when EVAs were
performed from the shuttle. The shuttle was isolated from the station so it
could lower its air pressure, AND the spacehab was isolated from the
shuttle because the tunnel between the two was also the airlock. So ducing
periods of EVAs, the transfer of goods could not proceed.

With an MPLM, the unit was transfered to the station with the arms, and
while the shuttle was isolated to conduct its EVAs, the station crew had
access to the MPLM to move the supplies out of the MPLM (and stuff destined
back to earth into the MPLM).

However, with the station's airlock now used, the shuttle is no longer
isolated for days during EVAs and this is no longer an issue,



I think the logic is that when the Shuttle is bringing up a station module
that is too large to co-exist with an MPLM, but leaves enough space to fit
a Spacehab. The spacehab is then loaded with various sundry supplies for
the inside of the station.


I think that there are also contractual issues between NASA and Spacehab
Inc where NASA committed to a certain number of flights using Spacehab.


Personally, with the number of shuttle flights finite, wouldn't it be
better to see NASA dump spacehab flights and replace spacehab with some of
the smaller modules such as cupolla , perhaps bring back EAS ?

I realise that in the original assembly plan, Spacehabs were planned as
fillers because those smaller modules would not have been delivered to KSC
yet, but in the current schedule, everything is sitting in a wharehouse
waiting to be launched. So why not put a few smaller modules in the cargo
bay instead of a spacehab ?
Thanks.
Instead of a touch of class, we have a touch of
bureaucracy.

John Doe wrote:

Personally, with the number of shuttle flights finite, wouldn't it be
better to see NASA dump spacehab flights and replace spacehab with some
of the smaller modules such as cupolla , perhaps bring back EAS ?

The Cupola is listed to go up with Node 3 on the last shuttle flight.

The Spacehab single module does make a lot of sense on the 12A.1/13A.1
missions. It allows a bit of logistics to be carried on otherwise busy
missions, when an MPLM simply won't fit in the bay, and at a time when
MPLM-based logistics flights are few and far between.

I realise that in the original assembly plan, Spacehabs were planned as
fillers because those smaller modules would not have been delivered to
KSC yet, but in the current schedule, everything is sitting in a
wharehouse waiting to be launched. So why not put a few smaller modules
in the cargo bay instead of a spacehab ?

What smaller modules? As noted above, the Cupola already has a launch slot.

--Chris

John Doe wrote:
waiting to be launched. So why not put a few smaller modules in the cargo
bay instead of a spacehab ?

I can think of several reasons:

- Weight and CG

there may not be enough weight and CG margin to bring two modules,
while there is for space hab. Spacehab with supplies could be less
dense than, say, a truss segment.

- Crew voted for bringing food & supplies for themselves over bringing
hardware for the station.

- There aren't two modules that will fit in the cargo bay together.

On Mon, 11 Dec 2006 02:31:19 -0500, John Doe wrote:

The last flight of Columbia had a large spacehab that was outfitted as a
lab with lost of research equipment inside.

The Spacehab Double Module. Two Spacehabs connected back to back.

But for station-bound flights, Spacehab brings no special functionality
compared to existing lockers inside the shuttle because everything must fit
through the narrow hatch between shuttle and station.

Well, it is powered, so Spacehab is probably a little better than an
MPLM if you have supplies that must be refrigerated or otherwise
powered during transport.

Personally, with the number of shuttle flights finite, wouldn't it be
better to see NASA dump spacehab flights and replace spacehab with some of
the smaller modules such as cupolla , perhaps bring back EAS ?

There's only one free CBM on Node 1 at present, and it will be needed
to temporarily park Node 2 next summer, so there's nowhere to put the
Cupola (destined for Node 3 anyway) yet.

I realise that in the original assembly plan, Spacehabs were planned as
fillers because those smaller modules would not have been delivered to KSC
yet, but in the current schedule, everything is sitting in a wharehouse
waiting to be launched. So why not put a few smaller modules in the cargo
bay instead of a spacehab ?

What smaller modules? The only thing as small as Spacehab is probably
Japan's logistics module, but again, there's nowhere to park it yet
that won't interfere with Node 2 install next summer.

Brian

On Sun, 10 Dec 2006 22:00:55 -0800, Sir Frederick
wrote:


Thanks. So why the Spacehab this flight, when the MPLM
in the past?

Spacehab is about half the size of an MPLM, thus NASA can get both a
resupply function (using Spacehab) and a large piece of the Space
Station (Segment P-5) on the same mission.

The alternative, I suppose, would be to launch both P-5 and S-5 on the
same mission, and use the other mission to launch the larger MPLM. But
this way, NASA gets to send some supplies up a little at a time,
instead of waiting for the one MPLM flight. They also spread out the
spacewalks by sending up P-5 and S-5 on separate missions.

Brian