Re: What Happened to the MMU?




<Dr.Colon.Oscopy@xxxxxxxxx> wrote in message
news:1170445715.802853.64790@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Feb 2, 8:40 am, h...@xxxxxxxxxxxxx (Henry Spencer) wrote:
In article <45c2c43a$0$24518$4c368...@xxxxxxxxxxxxxx>,

Jim <m...@xxxxxxxxxxxxxx> wrote:
What ever happened to the MMU? Why are they no longer used?

They're in storage, I believe. Basically, because there hasn't been a
good use for them lately.

The MMU was built on the assumption that the orbiter wasn't capable of
the
delicate maneuvering needed to dock with a satellite, e.g. for repairs,
especially if the satellite was spinning. But this turned out to be
untrue. In particular, it turned out that the best way to take the spin
off a spinning satellite is to just have spacewalkers in the cargo bay
reach up and grab it. (Moreover, the more complicated plans involving
the MMUs did not actually work terribly well on the Solar Max repair
and the Palapa/Westar salvage.)

That pretty much removed the MMU's reason to exist. For more mundane
tasks like working around ISS, it's easier and safer to crawl along the
structure, or have the arm hold you in position, than to fly free.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |
h...@xxxxxxxxxxxxx

The plans for Solar Max were in fact overly complicated, but I don't
think a failure of the MMU per-se contributed to mission problems.
The MMU docking pin on Solar Max had a screw placed in the a wrong
place (at build) that prohibited the docking, with the MMU interface.
(if I recall correctly the screw had no mission functionality at all).
The astronaut piloting the MMU (Pinky?) showed he could approach and
hit the target despite the spin speed. Now limitations as to how many
approaches he could make is entirely another story. With Palapa I'm
not so sure it was the MMU again, The docking mechanism was large and
ungainly (although built for the MMU) and repeated attempts failed,
and I'm not sure if a determination was made as to why. the docking
apparatus (I beleive it was made to fit inside the engine bell). I'm
not sure at higher spin speeds the arm would have done much
better ...................Doc

Wanted to thank everyone who responded. Most excellent.
Jim
--
Jim in Houston
NOSPaMjgoodrun@xxxxxxxxxxxxxxxxxxxx
Nurse's creed: Fill what's empty, empty what's full, and scratch where it
itches!!


.

Relevant Pages

  • Re: What Happened to the MMU?
    ... The MMU was built on the assumption that the orbiter wasn't capable of the ... The plans for Solar Max were in fact overly complicated, ... place that prohibited the docking, ...
    (sci.space.history)
  • Re: Chrome - competition for Borland?
    ... > I thought none of them had one built onto the chip itself until much ... > Or am I misunderstanding what MMU stands for? ...
    (borland.public.delphi.non-technical)