Cosmonautics
By Dennis Newkirk
COPYRIGHT 1995 by CSPACE PRESS INC. All rights reserved
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Oct./Nov. 1995
INTERNATIONAL SPACE STATION DEVELOPMENTS
This past summer Russian officials notified NASA that they would
like to reuse the Spectr and Priroda modules from Mir on the
International Space Station. While NASA officials are
understandably frightened with the prospect of another change in
the International Space Station (ISS) design, the Russians have
been moving carefully with revealing their plan.
The argument goes something like this; it is a bad idea to abandon
the relatively new Spectr and Priroda (to be launched next spring)
when Mir is left unmanned in early 1998 as the first Russian crew
arrives at the ISS. So they should be used on the ISS at least
until their design life ends. On face value this sound like a fine
idea and then the question of how to move the modules must be
addressed. The modules have a limited propellant supply, some of
which was used when they were docked to Mir. The modules usually
have enough propellant to make about 3 approaches for docking so
they should be able to fly to the ISS (provided Priroda has no big
rendezvous problems).
Once modules are flown to the ISS how do they dock? The modules
were specially made to dock to the forward port of a Mir like
module. After they dock to a 'birthing' port (the forward port on
Mir) they are moved to a side port using a crude manipulator arm
which is very restricted in its movements. There is no such
'birthing' port on the ISS, at least not until the planned June
1998 (3R) launch of the Universal Docking module and the docking
mechanism it uses is not yet clear, so the modules may or may not
be able to dock there. In any event, this plan involves 2
dockings, and 2 movements of modules and the added annoyance of
not being able to use the hundreds of kilograms of NASA
experiments on the modules until the second half of 1998, and
probably later accounting for the usual flight delays. So, flying
and docking the modules to the ISS becomes a fairly complicated
procedure.
It would be much easier to move the modules by just docking the
ISS (the combined FGB and Node 1 modules) to the Mir complex at
its forward docking port (see the gatefold diagram). This brings
to the ISS some capabilities it would not have until 1999 or 2000,
and all with just one docking. A bonus would be using the Kristal
and its docking module to replace the Universal Docking module
which provides an extra Soyuz docking port. This makes 3 person
permanent presence capability possible 6 months earlier than
originally planned (this is in addition to a 3 person
Russian/International crew which will occupy the ISS shortly after
the FGB launch). It also gives the crew many more experiments to
perform and more living space. None of these plans effect the NASA
side of the station and no "redesign" is needed, just revised
flight manifests to support NASA station crews earlier than
originally planned. Crew training would have to be started sooner,
and possibly software for control of the station will have to be
completed earlier than now planned to accomodate a larger initial
station mass.
Summarizing the Russian proposals:
- Dock Spektr and Priroda to the ISS
- Dock Mir and some of the existing modules to the ISS
- Dock Mir and all its modules and add the backup FGB module
to the ISS
- Dock Mir and all its modules and add the backup FGB module
to the ISS, and around 2002 replace the Mir complex
These plans all come with a price, that being accepting the risks
of using a 11 year old Mir module as a core of the Russian
modules. Risks of extending the life of Mir are several, first
lets examine the publicly known problems Mir already has. There is
a power shortage which forces tight scheduling of when equipment
can be used. Once already a crew member has forgotten to turn off
a piece of equipment overnight causing the core module to deplete
its power and caused days of work arounds and delayed scientific
research. Mir has also experienced a smoldering fire in some
electrical cables, and a life support system fluid leak, both of
which have been repaired. Mir's computer has also failed to
provide attitude control on some occasions, and in general Mir
often requires frequent crew actions to continue operating. This
is not necessarily a bad since Mir is a permanently manned space
station, it just lowers productivity.
And what could go wrong with Mir in the years ahead? The most
ominous disaster would be a catastrophic loss of atmosphere
endangering the crew. This happened on the Salyut 2 flight when
flying debris is believed to have punctured the hull on its 13th
day of its flight. This raises the next most dangerous event, that
being an explosion in the propulsion system which caused the
puncture in Salyut 2. Mir uses hypergolic propellants in 6 tanks
to fuel its attitude control engines and has pipes running the
length of the module which enable refueling from either the
forward or rear docking port. If the hypergolics leak and mix they
ignite. The pipes, fittings, valves and pumps of the propulsion
system all have limited lifetimes, the seals and gaskets age and
loose effectiveness. Inspection and servicing of the propulsion
system is almost impossible, so it is essential that the Russians
be able to judge the condition of the system. Mir's propulsion
system will be used for attitude control of the ISS when Progress
ships are not docked (which isn't very often), and it must serve
as a transfer conduit when refuelling the FGB to and from docked
Progress. A major leak in the system could be serious if it coats
the stations solar arrays, reducing power and requiring their
replacement. Failure of Mir's power system or control system is
not a as big a problem since the FGB provides a backup for these
systems, and some accounts say the Russians would add their backup
FGB to the ISS to provide another backup.
The biggest risk of using Mir is purely political and one of the
national pride of the USA. Docking the ISS to Mir would be adding
US elements to an existing Russian space station, and would injure
the US image of being the primary power behind the ISS. This image
has been fostered by NASA and agreed to by all parties, including
the Russians, in official agreements on cooperative space projects
primarily to gain US congressional support to funding. This is a
misguided and ill informed position in the first place since it
should be remembered that the Russians would never have come close
to completing Mir without NASA funds to launch Spektr and Priroda,
and NASA provided shuttle flights to Mir replacing flights once
planned for the Buran shuttles. But, in reality the political
perception is that docking Mir to the ISS would somehow belittle
the USA. This throws the entire ISS program into question and
opens funding to attack in Congress. The plan does make the ISS
project cheaper, faster and initially much better than it
otherwise would be which meets administrator Dan Goldin's goals,
lets just hope Congress can suppress its pride long enough to
realize it.
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Current Cosmonauts Status No. 9
(VSA058 ) © Sergey A. Voevodin 20.09.1995
Countdown is pleased to provide Sergey Voevodin the next 3 pages
for presenting one in his series of cosmonaut status reports. Data
in the list is as accurate as possible and is current as of
September 1995.