-
#120
by
Jim
on 15 Oct, 2009 14:37
-
, ie there are hard points on the exterior of the Docking Compartment which are capable of extremely high loading.
You have no proof of that
-
#121
by
Jim
on 15 Oct, 2009 14:40
-
if a way to connect those hard points to trunnions could be developed, then transport of Pirs in the Shuttle payload bay may be possible.
That has been the main issue all along. No possible without welding or drilling. The cradle is needed that has large circular clamps to hold it in place.
-
#122
by
Danderman
on 15 Oct, 2009 23:28
-
, ie there are hard points on the exterior of the Docking Compartment which are capable of extremely high loading.
You have no proof of that
I have some detailed shots better showing the hard points, which apparently use bolts to handle the loads.
-
#123
by
Danderman
on 15 Oct, 2009 23:33
-
if a way to connect those hard points to trunnions could be developed, then transport of Pirs in the Shuttle payload bay may be possible.
That has been the main issue all along. No possible without welding or drilling. The cradle is needed that has large circular clamps to hold it in place.
Identification of hard points on MRM-2 would obviate this concern.
-
#124
by
Jim
on 16 Oct, 2009 14:53
-
, ie there are hard points on the exterior of the Docking Compartment which are capable of extremely high loading.
You have no proof of that
I have some detailed shots better showing the hard points, which apparently use bolts to handle the loads.
All the items that are red are removed before flight. There are no flight hard points. The red rings are what clamps in a cradle would replicate
-
#125
by
Danderman
on 16 Oct, 2009 16:37
-
, ie there are hard points on the exterior of the Docking Compartment which are capable of extremely high loading.
You have no proof of that
I have some detailed shots better showing the hard points, which apparently use bolts to handle the loads.
All the items that are red are removed before flight. There are no flight hard points. The red rings are what clamps in a cradle would replicate
What do the red rings attach to? Actually, this is a rhetorical question - the red rings attach to hard points on Pirs.
The lower of the two red "rings" attach to hard points on the base of the Progress M PAO which are also on the separation plane of the spacecraft and the adapter section for Soyuz. Unfortunately, this PAO is detached from Pirs on orbit, so those hard points no longer exist. Fortunately, there is also a separation plane between Pirs and the PAO with hard points, for which I do not have a good photo, but I have seen images showing the hard points on the lower portion of Pirs.
I believe that I have identified a candidate location for placement of a Shuttle grapple fixture, as well.
-
#126
by
Danderman
on 16 Oct, 2009 16:43
-
All the items that are red are removed before flight. There are no flight hard points. The red rings are what clamps in a cradle would replicate
A point of information here: for return aboard Shuttle, Pirs would not require rings, as used on Earth, but, at the most, "half rings" since, AFAIK, there are no significant loads in the -Y axis for return to Earth. Obviously, given that at Baikonur, Pirs (and Progress) are transported via 360 degree rings, there are hard points around the entire circumference of the spacecraft.
-
#127
by
Jim
on 16 Oct, 2009 17:07
-
A point of information here: for return aboard Shuttle, Pirs would not require rings, as used on Earth, but, at the most, "half rings" since, AFAIK, there are no significant loads in the -Y axis for return to Earth.
Incorrect. There are the landing loads.
-
#128
by
Jim
on 16 Oct, 2009 17:11
-
What do the red rings attach to?
Not "hard points", that is why there are rings. They distribute the loads around the circumference of the vehicle.
-
#129
by
cneth
on 16 Oct, 2009 18:09
-
Taking a step back...
Just for a moment, let's presume a way exists to safely return this module and we do so.
Now what? The OP posits that we could "examine it on the ground". _Exactly_ what 'examinations' are proposed? What do we expect to find?
'We won't know until we get it back' is not a good answer - you'd need to do a lot better than that if you were asking me for the money. Even in basic research science, the principal investigators are required to come up with a pretty detailed description of what they are looking for and what they think they'll find before they get funding.
In particular, what would you do on the ground that you couldn't do on orbit, by taking samples, pictures, etc. on orbit and returning them? What new data would you gather that you couldn't get by analyzing data about similar materials gathered via MISSE or other space experiments?
-
#130
by
Danderman
on 17 Oct, 2009 19:13
-
This is a very good question, so I should probably answer it.
In a few years, there will be a great debate about the future of ISS. If you think there's a debate now about ending ISS in 2015-16, wait until 2014 or so when the money needs to found to keep ISS flying. Although few Americans will doubt whether Node 1 is flightworthy, just as the "aging Mir space station" (aging when it was less than 10 years old) caused many to question whether that platform was viable as early as 1995, some in Congress and NASA will call for the ending of ISS due to the age of Russian modules. This debate ultimately will rest on the technical decision about whether some of the older modules are still flightworthy.
We saw during the debate about the future of the Mir station that the amount of data considered during the debate was small - those who opposed Mir simply declared that the station was old, and therefore should be abandoned. A handful of anecdotes about failing components served to make the case that Mir should be de-orbited.
ISS is an extraordinarily expensive asset, and it would be unfortunate if its future were likewise debated and decided on the basis of anecdotes. Since the debate will likely focus on Zarya and Zvezda; however, due to difficulty of on-orbit examination of their structure and subsystems, a reasonable substitute would be to inspect Pirs, which shares many subsystems, and structural components, with the two larger Russian modules.
One major concern expressed during the Mir debate was the condition of the internal cooling loop. Since Pirs has a similar cooling loop, inspection of this subsystem. including the interface with Zvezda, would indicate the likelihood of potential future failures in the rest of the Russian segment. The ISS crew cannot access much of the cooling loop on Pirs, or the rest of the Russian segment. De-assembly of the Pirs hybrid docking adapter and its Triol lines will likely be required for accurate inspection.
Another area to inspect would be the Pirs nadir docking port, as well as the hybrid port; AFAIK, no probe and cone system exposed to space and multiple dockings over 10 years has ever been inspected to verify that it meets its certified lifetime.
The last major area to examine (that cannot be inspected by the crew) is the primary structure. It would be useful to determine whether the structure has been impacted by orbital debris - the only way to do this is to remove all the MLI and take a look, which is not practical on orbit.
Since safe return of Pirs would allow the debate over the future of ISS to be conducted on the basis of rigorous science and not anecdotes, the return is probably justified on that basis (assuming that empty Shuttle payload bays would be available in the outyears and that the return is technically feasible). However, the return of Pirs would also provide for additional downmass of some 2 tons, which could also be useful, plus Pirs may be refurbished and flown as a replacement for MRM-2 down the road, when that module reaches the end of its 5 year lifetime; alternatively, a refurbished Pirs could serve as a substitute for MLM, if that module never makes it to ISS.
-
#131
by
Zpoxy
on 18 Oct, 2009 14:18
-
The best solution I see is something like a spacelab pallet on which PIRS would be mounted: Think of HS376 during STS-51A. But I don't see the value.
Analyst
Well, the dimensions I found quote a length of 16 feet, making it too large to stand vertically in a spacelab pallet. Something like the arrangement for PMA-3 on STS-92 using the handling rings from the 2nd photo might work if the loads are acceptable. An alternative may be to capture both docking mechanisms if the handling ring hard points aren't up to the task.
-
#132
by
Danderman
on 21 Oct, 2009 18:48
-
Putting Pirs on a Spacelab Pallet simply adds mass, but does not solve the problem of attachment of Pirs to the Shuttle. Whatever bolts would attach Pirs to SLP could also be used to attach Pirs to trunnions and a keel pin, obviating the mass of the SLP.
-
#133
by
Jim
on 21 Oct, 2009 18:53
-
Whatever bolts would attach Pirs to SLP could also be used to attach Pirs to trunnions and a keel pin, obviating the mass of the SLP.
The SLP has the trunnions and a keel pin. It has many attach points that would be easier to hold fittings to the PIRS.
-
#134
by
Stan Black
on 28 Oct, 2009 18:05
-
Rather than have Pirs disposed of by having a Progress dock with it, and then at end of mission, dump Pirs into a destructive de-orbit, why not return Pirs on the Shuttle? Clearly, it would be difficult to return Pirs on the shuttle under the current manifest, but if the Shuttle program were stretched out, or additional flights were authorized, one of those later missions could probably return Pirs to Earth.
The questions are: why return Pirs, and how to do it?
Get Lavochkin to use one of their inflatable re-entry devices!
http://www.spaceflight.esa.int/irdt/factsheet.pdf
-
#135
by
Danderman
on 26 Dec, 2009 17:49
-
I think I have "solved" the cradle issue.
Looking at the attached photo of the Shuttle Mir Docking Module, I noticed that this is described as Energia technicians fitting trunnions to the module. This work was done at KSC. The question is whether there are special interfaces on the module to accept the trunnions, but I realized that interfaces seem to be the same as used to accept the loading rings used to transport the module.
Since Pirs uses the same loading rings, it appears that Pirs could be adapted to interface with a set of trunnions, as well, assuming the trunnions were similar to those fitted on MRM-1 (Rassvet) - which leads to the question as to whether the MRM-1 trunnions could be removed in situ (after docking with ISS) and transferred over to Pirs. Of course, this is hypothetical, since its not likely the Shuttle will around to return Pirs in a couple of years.
-
#136
by
Jim
on 26 Dec, 2009 18:07
-
I think I have "solved" the cradle issue.
Looking at this photo of the Shuttle Mir Docking Module:
http://science.ksc.nasa.gov/shuttle/missions/sts-74/images/high/KSC-95EC-1084.jpg
I noticed that this is described as Energia technicians fitting trunnions to the module. This work was done at KSC. The question is whether there are special interfaces on the module to accept the trunnions, but I realized that interfaces are the exact same as used to accept the loading rings used to transport the module.
Since Pirs uses the same loading rings, it appears that Pirs could be adapted to interface with a set of trunnions, as well, assuming the trunnions were similar to those fitted on MRM-2 - which leads to the question as to whether the MRM-2 trunnions could be removed in situ and transferred over to Pirs. Of course, this is hypothetical, since its not likely the Shuttle will around to return Pirs in a couple of years.
No, because there is nothing on orbit to align the trunnions. The orbiter requires the trunnions to be in very specific locations. They are optically aligned on the ground
-
#137
by
Danderman
on 26 Dec, 2009 19:34
-
It appears that the MRM-1 trunnions are welded on. They don't match up with the standard mounting locations (where the hemispheres meet the cylindrical section), for reasons that I won't go into here.
However, I haven't seen a good image of the keel pin yet, it may not have been installed yet, so this may be transferable to Pirs in the future.
Looking at the attached image, the red "transfer rings" that are bolted to Rassvet are attached in the following way:
Front ring: Attached to front hemisphere, apparently at the standard location (Pirs and Poisk rings were attached where the hemisphere meets the central section, whereas Rassvet's front transfer ring attaches to the same location, except that the ring itself is not located over this point, but is offset to the front, and special connectors carry the loads).
Rear ring: Attaches in the same manner as Pirs and Poisk, to the junction of the 2.2 meter cylindrical section and the frustrum that contains the rear docking adapter.
Transport:
If Rassvet followed the pattern of the Shuttle Mir Docking Module, the trunnions would not be attached until after shipment to Florida, and in the meantime, the transfer rings would be attached where the trunnions are today. However, Rassvet's trunnions were attached in Moscow prior to transport to the USA, as indicated below. This necessitated the "rear" transport ring to be offset from the real trunnion. This does not explain, however, why the front transfer ring is located in a non-standard position, but my guess is that the tiny airlock module, located on top of the main Rassvet body, is so close to the juncture of the front hemisphere and the 2.2 meter cylindrical section, ie the "normal" location for the transfer ring, that the ring is offset to avoid contact with the airlock module.
-
#138
by
Danderman
on 27 Dec, 2009 13:49
-
No, because there is nothing on orbit to align the trunnions. The orbiter requires the trunnions to be in very specific locations. They are optically aligned on the ground
This is a constraint, not a show stopper. The trunnion locations cannot be as precise as is implied above, since objects are removed from the shuttle on orbit, heated and cooled, and replaced back in the shuttle - thermal expansion should misalign the trunnion pins to some degree, but apparently the trunnion locations have enough "play" in them to accommodate any thermal expansion. LDEF comes to mind as a payload left in orbit for years, and then reinserted into the shuttle with no problem.
However, this constraint is significant. First off, the engineering of the trunnions for Pirs would have to be very precise. Secondly, its probable that the keel pin should be designed to have a little play, to allow the trunnions to be inserted before everything is locked down.
-
#139
by
Jim
on 27 Dec, 2009 15:02
-
This is a constraint, not a show stopper.
It is a showstopper.
Because the payloads go back to their original "thermo" condition, once in the benign environment of the payload bay and there is no residual stress being put in the orbiter by the trunnions.
