Creative NASA space bookkeeping re 'payload weight'

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Jim Oberg - 30 Jul 2005 03:11 GMT

The MPLM appears to be fully loaded, but there
is 'creative space book-keeping' by NASA at
their press kit, that includes the inert weight of
the MPLM (about 4.5 metric tons) as "delivered
payload", and then counts it AGAIN as "recovered
payload".

So all the news media is reporting that the shuttle
has delivered 'fifteen tons of supplies' to the ISS,
when at least a third of that is simply structure that
gets taken back to Earth.

If I did the accounting, I would not
give payload credit to transportation system
infrastructure elements, otherwise why not go
all the way and count 100 tons of Orbiter
structure as payload delivered as well?

Reply to this Message

Brian Gaff - 30 Jul 2005 08:04 GMT

Knowing bean counters of old, they probably know nothing of the problem you
describe, being more interested in getting out to the golf course.

:-)

Sorry silly mood today, What I'm saying is that maybe nobody actually
bothered to check this, as nobody techy enough bothers to read the press
releases.

Brian

Signature

Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email: briang1@blueyonder.co.uk
______________________________________________________________________________________________________________

> The MPLM appears to be fully loaded, but there
> is 'creative space book-keeping' by NASA at
[quoted text clipped - 13 lines]
> all the way and count 100 tons of Orbiter
> structure as payload delivered as well?

Reply to this Message

John Doe - 30 Jul 2005 19:11 GMT

> Knowing bean counters of old, they probably know nothing of the problem you
> describe, being more interested in getting out to the golf course.

No, The beencounters are seeing this from a shuttle point of view. Shuttle has
a 15 ton payload named "MPLM". It returns with a 13 ton payload named "MPLM".
They do shuttle performance and weight balance based on that number. They
don't care whether the MPLM is 15 tons with nothing in side, or if the MPLM is
only 1 ton with 14 tons worth's of supplies.

The problem is that PAO doesn't go through the trouble of finding out how much
cargo is inside the MPLM.

Reply to this Message

rk - 30 Jul 2005 21:30 GMT

>> Knowing bean counters of old, they probably know nothing of the problem
>> you describe, being more interested in getting out to the golf course.
[quoted text clipped - 8 lines]
> The problem is that PAO doesn't go through the trouble of finding out how
> much cargo is inside the MPLM.

I had no idea that the PAO did shuttle performance and weight balance as you
say.

And contrary to what you so authoritatively state, they are quite capable of
distinguishing between structure and payload in this particular context. Of
course, what constitutes payload is very heavily dependent on context.

Nevertheless, they make it quite clear that they are not guilty of the Sins of
Idiocy that you attach to them. Specifically:

http://www.nasa.gov/vision/space/workinginspace/mplm_module.html

Raffaello is a cylindrical module, about 21 feet long and 15 feet
in diameter, weighing almost 4.5 tons. It can carry up to 10 tons
of cargo packed into 16 standard racks.

Seems to me that the PAO got the concept down just fine.

And the PAO in their press kit gives additional information, and they are
quite clear that the weight for the whole assembly includes both the structure
of the MPLM and its contents.

The MPLM has a length of 22.4 feet and a diameter of 14.8 feet.
The MPLM weight at launch, with the cargo it contains, will be
18,166 pounds. The planned MPLM weight for return to Earth is
approximately 19,754 pounds.

Does your old Mac have subtraction capability?

It seems that the PAO did go to the trouble of finding out what the structure
weights and it's capability in terms of payload. They could be more careful
in their rounding ("about 21 feet" in one document and 22.4 feet in another)
and consistent in their presentation of numerical data.

The problem is that Mezei doesn't go through the trouble of finding out what
is being said before he so authoratitively trashes people and organizations.

Signature

rk, Just an OldEngineer
"These are highly complicated pieces of equipment almost as complicated as
living organisms. In some cases, they've been designed by other computers. We
don't know exactly how they work."
-- Scientist in Michael Crichton's 1973 movie, Westworld

Reply to this Message

Jim Oberg - 30 Jul 2005 23:39 GMT

Sorry, RK, NASA commentators for days on NASA TV
have described the mission as providing 'fifteen tons of supplies
for the I-S-S." The true number is about a third of that.

> And contrary to what you so authoritatively state, they are quite capable of
> distinguishing between structure and payload in this particular context. Of
> course, what constitutes payload is very heavily dependent on context.

Reply to this Message

rk - 30 Jul 2005 23:59 GMT

Hi Jim,

No problem,

I was just going by what they had in the press releases and JD's comment that
the PAO could not tell the difference between structure and payload. That's
of course different than they get it right all the time.

I haven't had time to watch much NASA TV, I'm afraid. 30,000 lbs is a lot of
stuff!

I do note that it's much better for most people to communicate accurately via
formal writing where you can stop and look at the words and have others review
them, particularly when you are writing to a large audience of essentially
unlimited people. Scrubbing or what we call "Tufte-hardening" writing is
easier than someone on TV speaking. Was this reading script (where it could
be scrubbed) or off the cuff remarks? Sounds like informal talking with
assumptions mixed in or the person speaking was not well briefed.

Good topic. Communicating technical information to a wide audience
unambiguously is something I'm interested in and worthwhile to discuss.
What's also interesting is your comment:

So all the news media is reporting that the shuttle
has delivered 'fifteen tons of supplies' to the ISS,
when at least a third of that is simply structure that
gets taken back to Earth.

I will, if I get some time, try to hunt down some coverage of this mission and
see exactly how it's reported. Good fact checking, they all should be doing
it.

Cheers,

-- rk

> Sorry, RK, NASA commentators for days on NASA TV
> have described the mission as providing 'fifteen tons of supplies
[quoted text clipped - 4 lines]
>> context. Of course, what constitutes payload is very heavily dependent on
>> context.

Signature

Reply to this Message

rk - 31 Jul 2005 02:43 GMT

[ snip ]

OK, I checked out how the two local papers wrote this up, the Washington Post
and the Washington Times (which uses AP) along with some others. The local
papers are in Washington, D.C., where NASA HQ is located and close to the
Goddard Space Flight Center. Interesting.

Washington Post:

The crew members spent Friday moving a nine-ton luggage
capsule into the station, preparing for Saturday's
spacewalk and inspecting the underside of the orbiter
for damage.

Washington Times and Houston Chronicle (both AP)

Discovery arrived loaded with 15 tons of much-needed supplies,
including a replacement gyroscope for one that failed in March.
Gyroscopes help steer the station. The shuttle crew planned to
leave with 13 tons of trash stowed aboard the station since
shuttles were grounded.

Signature

Reply to this Message

Space Forum / Shuttle / July 2005

Creative NASA space bookkeeping re 'payload weight'