International Space Station (ISS / Alpha)

GW Johnson · 2024-10-17 08:38:33

More on the leak in the ISS:

From the Space.com article summarized in AIAA’s “Daily Launch” for 10-17-2024:

ISS leaks among 50 'areas of concern' for astronaut safety: report
News
By Elizabeth Howell
published yesterday

NASA and Russia are working together on addressing the situation in the wake of an Office of the Inspector General report last month.

NASA and its Russian counterpart have identified 50 "areas of concern" related to a long-running leak aboard the space station, a media report states.

The leak has been ongoing since 2019 in the Russian segment of the International Space Station (ISS) and was the focus of a new report from NASA's Office of the Inspector General (OIG) published in September. While NASA and Roscosmos are addressing the leak, it remains a top "safety risk" for astronauts on board, the OIG report stated.

NASA officials, speaking in an exclusive with the Washington Post, said they are tracking four cracks and 50 other "areas of concern" on the ISS. The cracks have "all been covered with a combination of sealant and patches" by Roscosmos, NASA noted in a statement to the newspaper, and fixes are ongoing. Still, the leaking area is the top risk, at a 5 on a scale of 5, in NASA's internal risk assessments, the OIG stated.

"We have conveyed the seriousness of the leaks multiple times, including when I was in Russia earlier this year," associate administrator Jim Free added in an interview with the Post. Since the leaks are adjacent to a hatch, Free added that Roscosmos acquiesced to a NASA request to close the hatch as much as possible: “We've come to a compromise that they close it in the evening."

NASA astronauts also remain on the U.S. side of the orbiting complex to be close to their escape vehicles, in case of the need of evacuation, the agency noted in its statement to the news outlet. That said, NASA has stressed repeatedly that the leak poses no immediate threat to astronauts.

"Not an impact right now on the crew safety or vehicle operations, but something for everybody to be aware of," ISS program manager Joel Montalbano said in a news conference in February 2024 when the leak temporarily increased to 2.4 pounds per day, up from a historic low of 0.2 pounds per day.

The leak has been ongoing for five years and patches have been ongoing since it was first uncovered; agency officials noted in a Sept. 27 livestreamed briefing that repair work reduced the high leak observed in April 2024 by roughly a third.

The escaping air originated in a service module transfer tunnel in Russia's Zvezda module that launched in 2000. Zvezda, along with the rest of the ISS, is aging and requires maintenance to keep going in orbit. The ISS is supposed to last until 2030 to serve both NASA's staffing needs, and also to provide commercial low Earth orbit research. In the following decade, NASA hopes to have a set of commercial space stations ready to take over operations.

NASA's OIG is tracking several other risks that could imperil keeping the ISS going that long, ranging from a sudden micrometeoroid strike to supply chain issues.

SpaceX has been tasked to build a large Dragon-type spacecraft to remove the ISS from orbit, in a contract awarded by NASA earlier this year. The OIG stated it will be looking to learn more about the schedule, costs and risks associated with the new vehicle and the deorbiting plan.

My take on it:

The description of treating the 5 cracks says sealant and patches have been applied. That is NOT the way to fix cracks originating from cyclic loading. The critical step of crack stress relief presumably got left out, because there is no mention of it anywhere in the article. That step is to find and to drill-out the tip ends (plural! there are two ends to every crack!) to relieve the stress. Then (and only then) do you apply sealants and/or patches. Otherwise, the crack just keeps growing longer with time, right out from under your sealants and patches.

This "fix" for fatigue cracks has been known in aircraft design since the early 1950's. It was actually applied (and it worked) to the wing spars of the Lockheed Electra-II airliners, long before they ever became the Navy's P-3 fleet. Somebody (a reporter?) ignorant of this "fix" questioned the technician doing it. The technician replied "did you ever see toilet paper tear on the dotted line?" And THAT is the true origin of that old tale!

So, either both NASA and Roscosmos are ignorant of design practices for dealing with fatigue in duralumin alloys that date back almost 7 decades (which I doubt), or Roscosmos just wants to limp along risking a blowout rather than spending what it takes to fix the trouble. Which is either drill out the cracks or replace the module. What's truly disappointing is that NASA is not calling them out over this.

And y'all already bloody well know I am right about this! Any pressure vessel with growing holes in it, will eventually burst suddenly. Y'all know that, too. The risk here is a dead crew from a sudden explosive decompression that sucks all the air out of the station in only several seconds! Close the damned hatch, and keep it closed! Or fix the bloody problem, but do it right!

I hope someone at NASA reads this post!

GW

Update 10-18-2024:

If you don't believe the Zvezda module cracking apart would depressurize the station suddenly, killing the entire crew, then consider this. Think about the "PA kick load" that happens like an impact force when two sections of a pressure vessel part from each other. ISS operates at about 1 std atm internal pressure, which in US units is 2116 lb/sq.ft. I don't know the diameter in Zvezda where the cracks are located, but let's just presume it to be about 6 feet. If circular, the cross sectional area is near 28.3 sq.ft. The PA kick load is pressure x area upon which it acts, or some 59,830 lb = 27.1 metric tons-force. Bigger diameter, bigger force, proportional to diameter squared! Twice the diameter is a 4 times bigger force!

The effect that load has upon adjacent structures is a sudden impact, not a gently-applied steady load, so you must at least double that value for estimating stresses in related structures, to around 120,000 lb or 54.3 metric tons-force! A sudden impact that large will break up much of the station, tearing module from module, and letting all the air out of them, pretty much all at once! No one in the crew will have time to shelter anywhere!

And THAT is why I think the risk of these propagating cracks is so severe! And so urgent to address!

Last edited by GW Johnson (2024-10-18 08:34:29)

GW Johnson · 2024-10-18 08:36:01

For you skeptics about the leaking cracks in the Zvezda module, I just added a couple of paragraphs to post 726 just above, describing the consequences if that module busts open.

GW

tahanson43206 · 2024-10-18 09:11:21

For GW Johnson!

There is an opportunity for you to clarify if the leak is in the Zvezda module, or in a separate part that could be cut off.

Air leaks
Since September 2019, the Zvezda module has been experiencing a worsening air leak. The source appears to be microscopic structural cracks within the small tunnel connecting Zvezda to a docking port used by Progress cargo spacecraft. The leak rate has increased from initially less than 1 pound (0.45 kg) per day to 3.7 pounds (1.7 kg) per day as of April 2024. While both NASA and Roscosmos suspect internal or external welds, the root cause of the leaks remains unknown. The agencies have said that if the leaks reach an untenable level, they plan to close the hatch leading to the tunnel, however that would result in the loss of the docking port. Internally, NASA has classified the leaks as a high-risk threat to spaceflight activities, potentially leading to "catastrophic failure." However, Roscosmos has expressed confidence in their ability to monitor the leak and close the hatch before it becomes unmanageable.[30][31]
Interior

My reading of the Wikipedia update is that the Russians would like to keep their docking port.

My question is: Can the tunnel be severed from Zvezda?

I understand there is a hatch to the tunnel that can be closed.

If the hatch to the tunnel is closed and the tunnel is severed from the hatch, then the opportunity (presumably) exists to connect a replacement tunnel and re-install the docking port.

(th)

GW Johnson · 2024-10-18 14:15:58

Here's a quote from the article I quoted in post 726: "The escaping air originated in a service module transfer tunnel in Russia's Zvezda module that launched in 2000."

I do not know details, but the words would indicate the transfer tunnel is part of the Zvezda module.

Yes, there is a hatch to the Zvezda module that can be closed. Closing it eliminates access to a docking port that is currently often used. The kick force happens whether that hatch is open or closed, if the module is pressurized.

As I understand it, the Russians have agreed with NASA to close that hatch, but only "at night".

GW

kbd512 · 2024-10-18 21:24:22

Someone needs to tell the Russians that it's time to set Condition Zebra before the entire station is lost to an explosive decompression event. Now that we know where the source of the problem is, it would be stupid to kill everyone aboard because it's "inconvenient" to dog all hatches.

tahanson43206 · Yesterday 04:41:45

There are Russians and there are Russians....

The situation is far more difficult to solve than it needed to be from a technical point of view.

The decision by Mr. Putin to invade Ukraine has made it far more difficult to solve this problem as just humans.

If part of the problem is cash flow in Russia (and it may well be due to allocation of resources for military purposes) the the US might be able to pay for a replacement tunnel. If we were still in the Yeltsin days such a cooperative effort might be possible.

Such a cooperative undertaking may still be possible, if the right human personalities are available.

This is 5% a technical issue, and 95% a human relationships problem.

(th)

GW Johnson · Yesterday 13:37:16

It's a problem driven by money and politics, pure and simple! Neither of which is a proper basis for making space crew safety decisions, as we already know from two dead shuttle crews.

GW

tahanson43206 · Yesterday 14:24:47

For GW Johnson re #732

To say that human relationships are based upon money and politics is to over simplify a complex set of currents in "human space"

It appears to me that some people are motivated by money, but many are motivated by other interests.

A scientist who invests a lifetime learning everything there is to know about a species of insect is NOT motivated by money.

A mother who cares for a child (or any family member) is NOT motivated by money.

There are certainly humans who are motivated by emotions that get translated into politics.

However, I expect that neither the Americans nor the Russians on the ISS are motivated by either of these.

Human society appears (to me) to include individuals who operate under a wide range of motivations.

In the case of the problem we seem to see at the ISS, of Russians wanting to keep using a dangerous piece of equipment, it seems to me that the services of a true diplomat are called for.

Whatever the motivations of the players may be, the (hypothetical) diplomat we need would be able to find solutions that meet the needs of the participants, and if some investment on one side or the other is needed, so be it.

I would imagine that the Russians in the ISS community are reluctant to experience total decompression, but whatever their feelings may be are ruled by superiors on the ground, and ** there ** the motivations become more complex.

If the need is to keep a docking port working as long as the Russians need it, then a solution that might work for them would be finding a way to replace a failing docking port with a new one. It might even turn out that a liner through the existing tunnel would solve the leak problem. My assumption here is that this is a human relations problem primarily, with about 5% technical issue to be solved, if good will can be mustered to allow effective thinking.

Update:
The proposed liner for the interior of the tunnel might be fabricated in 120 degree sections so they can fit through the existing docking port. the liner section could then be bolted together as a first step in installation, and then welded to each other, and to the tunnel.

The tunnel need not bear the stress of the 90 minute temperature swings, if the existing tunnel remains in place outside the liner.

(th)

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#726 2024-10-17 08:38:33

Re: International Space Station (ISS / Alpha)

#727 2024-10-18 08:36:01

Re: International Space Station (ISS / Alpha)

#728 2024-10-18 09:11:21

Re: International Space Station (ISS / Alpha)

#729 2024-10-18 14:15:58

Re: International Space Station (ISS / Alpha)

#730 2024-10-18 21:24:22

Re: International Space Station (ISS / Alpha)

#731 Yesterday 04:41:45

Re: International Space Station (ISS / Alpha)

#732 Yesterday 13:37:16

Re: International Space Station (ISS / Alpha)

#733 Yesterday 14:24:47

Re: International Space Station (ISS / Alpha)

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