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ISS a safe haven?

Posted by: Andy Hill - Fri Sep 02, 2005 1:33 pm
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ISS a safe haven? 
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Post ISS a safe haven?   Posted on: Fri Sep 02, 2005 1:33 pm
I was always a bit sceptical about the ISS acting as a safe haven for stranded astronauts with a damaged shuttle. Questions like could NASA actually launch another shuttle in time or what if the second shuttle was damaged in the same way weren't really answered. Now it seems that the whole idea is a non-starter as according to this article after a few assembly missions the ISS will not be able to have a shuttle permanently docked as its configuration would make it unstable.

If this correct why was this not mentioned by NASA before?

http://www.flightinternational.com/Articles/2005/09/02/Navigation/177/201312/Space+station+rescue+plan+flawed+after+STS+115.html

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Post    Posted on: Fri Sep 02, 2005 2:40 pm
I thought the original plans had a spaceplane docked to the iss that would be used to escape, and the shuttle would move up temporarily to add parts in orbit? Still rather be on the station that a shuttle! :)

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Post    Posted on: Fri Sep 02, 2005 3:19 pm
Rob Goldsmith wrote:
I thought the original plans had a spaceplane docked to the iss that would be used to escape, and the shuttle would move up temporarily to add parts in orbit? Still rather be on the station that a shuttle! :)


NASA cancelled the X38 which was supposed to be a crew return vehicle permanently docked to the ISS due to costs, ESA was a bit put out by this as they had stumped up some of the cash for its development. Pity really as it might have resulted in a usable vehicle while the shuttle is grounded.

Their next plan was to buy a couple of Soyuz but they ran into the ITAR rules. If the current legislation under review in the US is approved which gives NASA the ability to step around ITAR they will be able to buy Soyuz off the Russians, so I guess its plan B again. Failing that NASA's own rules will have to be changed as they currently dont allow their astronauts to stay on the ISS without an escape craft, this is Soyuz at the moment but early next year that agreement ends so there will be no ride home for US astronauts in an emergency.

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Post    Posted on: Fri Sep 02, 2005 4:46 pm
After this hurricane--we will be lucky if we even have a NASA. Some debris hit an ET, and the others got wet. If the funding for Griffin's plan--like it has a chance now--were to pass, that disgusting mob would do a better job destroying Michold than any storm surge ever thought about doing.


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Post    Posted on: Fri Sep 02, 2005 5:45 pm
Shucks, Andy, you shouldn't ever believe sensationalist reporters.

OK, so you're Griffin now in this worst-case scenario...

Do you:

A). Lose ANOTHER crew

OR

B). Jettison one lousy solar panel truss?

The notion so frequently forwarded by the press that "good lord, nobody at NASA has thought about this!" is patently misguided and yet has become so ubiquitous that it is taken by the general public as an accurate description of "how things really are" That's just not fair to all of the bright and hardworking people that have to really lose sleep about this kind of thing.


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Post    Posted on: Fri Sep 02, 2005 6:21 pm
I'm sure you're right that NASA thought about this and that given a choice it would be bye-bye truss. I just thought that it was a point that hadn't been made very clear to people and that it makes the scraping of the X-38 even more surprising.

If the X-38 was canned for financial reasons these must have been pretty significant when compared to throwing a large part of the ISS away. Even if the jettisoned parts were not that costly, the extra shuttle flights and time expendature should have covered the X-38 costs.

Now I know with hindsight its easy to say that the X-38 should have been continued but I would have thought given the alternatives of butchering the ISS or being reliant on the Russians NASA would have kept the project going, especially since it had started to produce actual hardware.

I'm not sure whether the X-38 could ever have been modified to launch on a booster as a crew ferry as it was designed to be carried to the ISS in a shuttle payload bay but once the thing had been built that would have been the next logical step with the shuttle's problems. It would have at least enabled NASA to gain experience of a small spaceplane design that would probably have been safer than the shuttle.

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Post    Posted on: Fri Sep 02, 2005 6:49 pm
Well, the "safe haven" concept really wasn't adopted until after Columbia was destroyed, and at that point the x-38 had already been cancelled. One would think that they may have re-visited the idea after that, but it seems that the decision was made to put everything into CEV instead.


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Post    Posted on: Fri Sep 02, 2005 7:09 pm
SawSS1Jun21 wrote:
Well, the "safe haven" concept really wasn't adopted until after Columbia was destroyed, and at that point the x-38 had already been cancelled. One would think that they may have re-visited the idea after that, but it seems that the decision was made to put everything into CEV instead.


Yes your right about the timing but I'm surprised that NASA didn't restart the X-38 project
the article below tells how it evolved out of the HL-20 and spacewedge projects and was anticipated to evolve into a full crew transport that could launch on a range of vehicles (including Arianne and Zenit). NASA even had Scaled making the final flight models, I expect these are in storage somewhere gathering dust.

The article quotes a project cost of $500M which seems a pretty good bargain compared to the return to flight costs or even a single shuttle flight.

http://www.astronautix.com/craft/x38.htm

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Post    Posted on: Sun Sep 04, 2005 12:49 am
Thanks for an interesting link. Unfortunately, all lifting bodies are doomed as payloads to be launched on top of commercial rockets (but not if stored inside the Shuttle Cargo Bay). This is like putting fins on the front of an arrow – it wants to turn around backward! This is a serious problem, and the airloads on rockets due just to wind shear are quite large near “Max Q”. Aerodynamically neutral vehicles are fine, with the active guidance providing the necessary attitude control. But these systems simply aren’t capable of countering the massive loads which can be created by top mounted winged or “lifting body” payloads. This is the fact that makes the “NASA released” drawings of a winged CEV either a hoax or fraud, depending on your view!

I don’t think NASA has ever liked “stop gap”, economy solutions when more elegant approaches are conceivable: “interim” solutions tend to become permanent. But sometimes conceivable elegant designs and conceivable funding don’t match!


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Post    Posted on: Sun Sep 04, 2005 5:34 am
Well, let's face it: the Space Shuttle itself was supposed to be an interim solution to the getting-stuff-to-orbit problem until space stations and better vehicles got built and we continued outward. Instead of a waypoint, it became a destination.

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Post    Posted on: Mon Sep 05, 2005 3:52 pm
I would think the shuttle would be cast adrift before a space station truss. After all, the reason the shuttle would be there is because it could no longer safely reenter.


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Post    Posted on: Mon Sep 05, 2005 4:53 pm
If I understand rightly the problem would be that there would not be enough room on the station by itself and the shuttle's extra capacity would be needed for the supplies and personnel in the event of a shuttle problem. However this would result in the ISS being unstable if the truss was attached as well.

I'm assuming that short periods of instability are acceptable as shuttles will have to dock with the ISS with the truss there during its construction, so perhaps there is a problem that occurs if one is docked for 60 days (time taken to launch second shuttle).

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Post    Posted on: Tue Sep 06, 2005 4:55 am
Is the ISS really a safe haven? I mean how long are we really talking about? In reality, I don't think that it was a serious fall back position. If one shuttle hadn't made it then there was a good chance the next wouldn't either. Without another shuttle there was no chance that you could rescue everyone as the Soyuz are the only vehicle available - they seat 3 in special seats. You'd need at least 2 in quick succession otherwise you run out of supplies. No, the shuttle missions have always been risky and I think that it was never seriously considered that if you got one up, it couldn't get back down again. Was that the real reason that the people on the Columbia were not advised of the damage to their vehicle? NASA knew that it didn't matter in the end. They couldn't have rescued them anyway. :cry:

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Post    Posted on: Tue Sep 06, 2005 1:51 pm
Andy Hill wrote:
If I understand rightly the problem would be that there would not be enough room on the station by itself and the shuttle's extra capacity would be needed for the supplies and personnel in the event of a shuttle problem.
There is plenty of room on the ISS for more people but consumables would get used up faster. The shuttle carries supplies for the expected length of it's flight plus a few days reserve. I am not privy to NASA’s plans, but it seems to me that the crew would stay on the disabled shuttle until the reserve ran out, then dock with the ISS as a last resort. After that, if the ISS became unstable, the disabled shuttle would be jettisoned. Wouldn’t they need to do that anyway to free up the docking station for the rescue shuttle? Or are there two separate docking stations that shuttles can use. I know there are at least 2 for the soyuz.

By the way, I never heard about the completed ISS being unstable with a shuttle docked. Isn’t the ISS designed to have a shuttle docked to it for routine service? Or is it maybe only unstable with 2 shuttles docked?

(EDIT) On reading your originally linked article Andy, I notice that is says
Quote:
STS 115 will add a solar panel truss segment to ISS and the station will become inherently unstable until the delivery of another truss expected three to four flights later.

This means a damaged orbiter could not be docked to the ISS for any prolonged period during that time.
It doesn't really say that the docked shuttle causes the instability. In fact it is looks to me like it says the ISS is unstable without a shuttle. And there is no justification to the statement that a shuttle could not remain docked for an extended time. I would like to see another source before just believing that statement. Call me silly, but I don't have much faith in the media's ability to report accurately.


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Post    Posted on: Tue Sep 06, 2005 5:48 pm
campbelp2002 wrote:
I am not privy to NASA’s plans, but it seems to me that the crew would stay on the disabled shuttle until the reserve ran out, then dock with the ISS as a last resort. After that, if the ISS became unstable, the disabled shuttle would be jettisoned. Wouldn’t they need to do that anyway to free up the docking station for the rescue shuttle? Or are there two separate docking stations that shuttles can use. I know there are at least 2 for the soyuz.

By the way, I never heard about the completed ISS being unstable with a shuttle docked. Isn’t the ISS designed to have a shuttle docked to it for routine service? Or is it maybe only unstable with 2 shuttles docked?


I'm pretty sure that only one shuttle at a time can be docked to the ISS, at least at the moment. Perhaps in the future a second docking port will be installed, the X-38 would have had to remained docked during shuttle visits.

campbelp2002 wrote:
It doesn't really say that the docked shuttle causes the instability. In fact it is looks to me like it says the ISS is unstable without a shuttle. And there is no justification to the statement that a shuttle could not remain docked for an extended time. I would like to see another source before just believing that statement. Call me silly, but I don't have much faith in the media's ability to report accurately.


I think the terms accurracy and media are mutually exclusive. This is why I made the original post as the point about instability hadn't been raised in the past and I thought it was a little odd that it was being mentioned only now.

I must admit I had assumed that the instability would be caused by the shuttle but on re-reading the article you might be right that the ISS is inherently unstable during this phase of construction. This might have big consequencies if there is another delay in the shuttle programme during that phase of assembly.

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