Shenzou Capsule left in orbit a big Risk to Returning Crew?

Although this question belongs at sci.space.tech, I am asking it here
because I know Mr. Oberg is a frequent participant here and he's
probably the one who can answer this question (although it is open to
anyone).

Doesn't the Chinese practice of leaving their Forward Orbiting Module
up in space after the return of the crew to Earth put them in the same
dangerous position the Soviets use to place themselves in when the
Soyuz program was first started?

The Soviets use to break up the Soyuz spacecraft BEFORE the reentry
try. If something went wrong there was only a limited amount of power
and air in the Descent Module before a second (or third) attempt was
made. The Soviets changed the practice of breaking up the Soyuz DURING
descent.

Or is it that the Orbital Module separates from the Shenzhou (remaining
Descent and Service Modules) and the two remaining modules separate
during re-entry?

Any replies would be greatly appreciated.

Thanks,

DJV

wrote:


Doesn't the Chinese practice of leaving their Forward Orbiting Module
up in space after the return of the crew to Earth put them in the same
dangerous position the Soviets use to place themselves in when the
Soyuz program was first started?

The Soviets use to break up the Soyuz spacecraft BEFORE the reentry
try. If something went wrong there was only a limited amount of power
and air in the Descent Module before a second (or third) attempt was
made. The Soviets changed the practice of breaking up the Soyuz DURING
descent.


I'd never thought of that, but you're right, that could be a problem.
They obviously have to separate the orbital module prior to retrofire so
that it remains in orbit.
One of the big problems of the old Soviet practice (as they found out
the hard way) was that the Soyuz's toilet was in the orbital module.
I assume that's where it's at on the Shenzhou also.
Other than the toilet, the other problems one could run into would be
atmosphere recycling gear and food and water.
Soyuz had its main atmosphere recycling gear in the orbital module, as
well as it's main food and water storage there (there are interactive
cutaways he http://www.russianspaceweb.com/soyuz.html)
You could get around the main problem by having your main air recycling
gear in the reentry module.
On the Shenzhou V flight, the taikonaut never left his seat, so I assume
that they never opened the hatch between the reentry and orbital
modules. This implies that there is at least some independent air
recycling ability in the reentry module.

Pat

wrote:

The Soviets use to break up the Soyuz spacecraft BEFORE the reentry
try. If something went wrong there was only a limited amount of power
and air in the Descent Module before a second (or third) attempt was
made. The Soviets changed the practice of breaking up the Soyuz DURING
descent.
Intersting point. One difference is that Shenzou (including the DM) is
a bit roomier than the Soyuz. So it is possible that they have enough
backup stuff in the DM to make a few days tolerable.

The service module does the retrofire, so power after a failed deorbit
burn shouldn't be too much of an issue (the Shenzou orbital module,
unlike soyuz, does have solar panels, but there are also larger panels
on the SM)

In response to Pats post, toilet facilities for emergencies shouldn't
be a show stopper... it wouldn't be the first space program to depend
on diapers (or bags bags).

hop wrote:


In response to Pats post, toilet facilities for emergencies shouldn't
be a show stopper... it wouldn't be the first space program to depend
on diapers (or bags bags).



The write-up on the Soyuz TM-5 "anomaly" seemed to indicate that the
cosmonauts found the toilet situation more than a little annoying. If
you weren't planning to need diapers or bags and didn't have any
along.... :-D

Pat

Pat Flannery wrote:

The write-up on the Soyuz TM-5 "anomaly" seemed to indicate that the
cosmonauts found the toilet situation more than a little annoying. If
you weren't planning to need diapers or bags and didn't have any
along.... :-D

Pat
Right, I was just saying that assuming the Chinese are aware of that
scenario, it wouldn't be too hard for them to prepare for it. It might
still be messy and unpleseant, but need not be more so than Gemini or
Apollo (oops, there we go with the comparisons again :P)

Thanks for the input.

I figured the main gear was in the Orbiting Module since there is the
speculation that the Chinese are planning on future rendevouz with
previous mission Orbiting Modules and I also believe their man-tended
Space Laboratory will consist of glorified Orbiting Modules linked
together. I doubt the visiting Shenzhous would be required to provide
the life support systems for the combined structures. And if they are,
the air/fuel refill systems would have to come from. . . the Orbiting
Modules! (due to the structural geometry)

I also really doubt that the Chinese designed Shenzhou to have back-up
equipment (other than around a few hours like Soyuz has) in the Descent
or Service Modules given that weight is at a premium.

Your comment of the Orbiting Module separating itself from the rest of
Shenzhou prior to the deorbit burn may also mean that the speculation
that Shenzou 8 will rendevouz with the Orbiting Module of Shenzhou 7
may be wrong. They may just break off from the Orbiting Module during
Shenzhou 8, back off, and then try a docking (automatic or manual).
Unless they want to test a full automatic rendevouz AND docking system.

Anyway, thanks again.

DJV

Too bad for that poor female Taikonaught if something does go wrong and
they have to resort to this.

DJV

wrote:
Thanks for the input.

I figured the main gear was in the Orbiting Module since there is the
speculation that the Chinese are planning on future rendevouz with
previous mission Orbiting Modules and I also believe their man-tended
Space Laboratory will consist of glorified Orbiting Modules linked
together.
....

China does plan to have dedicated space station modules:
http://www.astronautix.com/craft/chiatory.htm along the lines of the
Salyut, FGB, Kvant, etc... Perhaps, they'll tinker with Orbital
Modules for a while to test out docking procedure, but eventually they
seem to plan to have a 'proper' space station running. Which will
raise questions of what use such capable orbital modules would be. On
the Soyuz they serve as some extra room with some facilities for the 2
day transfer to the station. 2 days to minimize fuel reqs.

If China plans to have a 'proper' modular station with closed loop
ECLSS, and fuel transfer capacity, I'd design the Shendzhou with a same
day transfer by adding more fuel to the service module, *instead* of
beefing up the Orbital Module. The Orbital Module is really a rudiment
conceptually in a station centric architecture. There is really no
need for the independent propulsion or solar panels on the OM if one
has a space station. So, why did they overdesign it? Perhaps for some
sort of lunar fly-bys?

wrote:


Your comment of the Orbiting Module separating itself from the rest of
Shenzhou prior to the deorbit burn may also mean that the speculation
that Shenzou 8 will rendevouz with the Orbiting Module of Shenzhou 7
may be wrong.


They may just break off from the Orbiting Module during
Shenzhou 8, back off, and then try a docking (automatic or manual).
Unless they want to test a full automatic rendevouz AND docking system.



That would mean that the junction between the descent and orbital
modules is some sort of docking collar.
That would be fairly complex to engineer, although I imagine that you
could arrange it so all orbital modules have female docking adapters on
the descent module end and male ones on the top end.
That way you could just keep joining more and more of them together end
to end, as the descent module wouldn't need a docking collar at its
junction to the attached orbital module.
The resulting long skinny space station wouldn't be the easiest thing to
move around in though.
If the first module of the "Stick Station" had female docking adapters
at either end, you could alternately add modules to either end, and end
up with a station that has a docking port at either end for new
Shenzhous to dock to, so that you could have a permanent crew on board
if you wished by doing the Soyuz ship-swapping crew return technique.

Pat

Pat Flannery wrote:


The resulting long skinny space station wouldn't be the easiest thing
to move around in though.
If the first module of the "Stick Station" had female docking adapters
at either end, you could alternately add modules to either end, and
end up with a station that has a docking port at either end for new
Shenzhous to dock to, so that you could have a permanent crew on board
if you wished by doing the Soyuz ship-swapping crew return technique.


Now that I think this over, there is something else you could do here if
you have a orbiting Shenzhou orbital module with docking adapters at
either end.
Once you have a double female docking adapter orbital module in orbit,
another three or four spacecraft go up- each is a unmanned Shenzhou
service module with a propellant filled orbital module attached to its
front end (no descent module).
These are docked to the double collared orbital module one after the
other, and their service modules are then jettisoned, exposing a female
docking adapter on their bottom end and plumbing by which their
propellant supplies are interconnected. (the Soviets developed this sort
of fuel transfer technology with Progress)
Then another one goes up and docks to the end, but in this case the
service module stays attached.
A manned Shenzhou docks to the far end of the station, and the whole
works uses the engines on the service module from the unmanned end and
its propellant modules to head for the Moon.
You have enough fuel on board and you might even be able to brake into
and out of lunar orbit.
Then of course comes the second ship assembled the same way...carrying
the lunar lander, and the two rendevous in lunar orbit.

Pat