It's so complicated:' Boeing Starliner teams diagnose helium leak ahead of June 1 astronaut launch

[Admin]

NASA and Boeing are still working through "complicated" issues arising from a small Starliner spacecraft helium leak. Launch is June 1, but that's pending a flight readiness review.

It's so complicated:' Boeing Starliner teams diagnose helium leak ahead of June 1 astronaut launch : Read more

 

[Homer10]

Helium is hard to contain. Especially at high pressures. It has a knack for oozing through many metals and escaping. There's no crack or anything like that, it just can ooze through metal latus structures. Pressure changes a lot with temperature, and its really expensive. You have to have a good way of detecting helium to see where the leak is coming from. There are other ways, all involve disassembly, and messing around with the system and waiting for pressure changes. This is going to be a hard one to fix.

 

[Unclear Engineer]

This article needs some work.

First, helium is not a "non-inert gas" - it is inert, so it is a non-inflammable gas.

Second, wasn't it was already announced yesterday that the June 1 launch date is out, and launch has been rescheduled for June 5?

And, frankly, this business of "studying the issue with software" doesn't leave me with a good feeling. If they completely understood the situation, then it would not be leaking. There is a problem with one seal. Why? What will happen to that seal when it is subjected to vibration, stress and temperature changes during launch and while in the space environment? And, will that cause problems with other seals, in addition to this one?

Yes, the leak rate needed to strand the astronauts in space is much larger. But, how do we know what the limit is for the leak rate for this craft, given that it is already having a problem?
Let's not have another life-ending "mishap" that could have been avoided by actually dealing with an issue instead of "analyzing it away" with a computer program involving a lot of assumptions. We do not have a great track record with "assumptions".

 

[Torbjorn Larsson]

It may be that they haven't considered the flight risk and its protocol before, which would be ironic given the time they have taken to develop the bucket of bolts.

Of course next to the hydrogen used in the Atlas upper stage helium is the gas you least want to see in a gas system. They both leak like crazy through seals and in the case of hydrogen making metals brittle.

Helium is hard to contain. Especially at high pressures. It has a knack for oozing through many metals and escaping. There's no crack or anything like that, it just can ooze through metal latus structures.

Fact, but it can also more easily be trapped than hydrogen.

Helium diffusion in metals is a complex process owing to the very low solubility of this element in solids, in general, and to its ability to be trapped by vacancy type defects and to form stable bubbles, in particular [1], [2].

https://www.sciencedirect.com/science/article/abs/pii/S0168583X03021414

 

[DrRaviSharma]

As a Fuel Cell standards developer in a SAE team, I can say that Hydrogen is very hard and flammable to deal with especially due to diffusion and similarly but less reactively Helium being light is hard to keep under control. Also recall Apollo 13 mishap was due to leakage in Hydrogen Oxygen fuel cell for power.

Starliner is a risk laden test mission and fortunately catching these glitches are a great review, often too close to call.

I hope they do not compromise with safety.
Fortunately they have history of successful non-crew docking with this spacecraft piece.
Regards.

Ravi
(Dr. Ravi Sharma, Ph.D. USA)
NASA Apollo Achievement Award
ISRO Distinguished Service Awards
Former MTS NASA HQ MSEB Apollo
Former Scientific Secretary ISRO HQ
Ontolog Board of Trustees
Particle and Space Physics
Senior Enterprise Architect
SAE Fuel Cell Tech Committee voting member for 20 years.
http://www.linkedIn.com/in/drravisharma

 

[mcswell]

"The leak began at 7 pounds per square inch (psi) and has increased to between 50 psi and 70 psi": Huh? Leaks aren't measured in psi, they're measured in mass or volume of the substance leaking. It *sounds* like they're saying the leak started when the helium was pressurized to 7 psi and increased when they pressurized the helium to 50+ psi. One would expect that, of course (unless the extra pressure made the seals expand into their grooves or something), but then they wouldn't say it increased *to* 50 psi. So what is this sentence trying to say?

 

[mcswell]

Fact, but it can also more easily be trapped than hydrogen.

Not sure what you're saying. Helium atoms are larger than hydrogen *atoms*, but helium molecules (which consist of a single helium atom) are smaller than hydrogen *molecules* (which consist of two hydrogen atoms). So in the molecular state (which is where you find gaseous un-ionized hydrogen and helium), helium tends to leak more easily than hydrogen.

 

[Unclear Engineer]

As I posted before, this article needs some work. But, it still says that helium is a "non-inert gas". So, it seems pretty clear that nobody with much science background has gone over it yet for accuracy.

I suspect that the original press release said something like the leak started at 7 psi and the leak rate increased as the pressure was increased to 50 psi.

I would not venture a guess on the leak rate in mass per unit time, based on that, because we are not talking about some engineered orifice with a clear flow path. The increased pressure would clearly increase the driving force, but may also affect the effective flow area by distorting the material, which might increase or decrease the effective flow area.

 

[Atlan0001]

The discussion reminds me of the movie "The Hindenburg", and the dialog back and forth concerning the German use of hydrogen versus the American use of helium . . . and the Germans wanting to buy helium from the Americans for use in their Zeppelins like the 'Hindenburg' (too late!).

 

[gybognarjr]

Boeing/ULA builds with complicated rockets, space vehicles, everything they do is slow, late and breaks down often. Space X designs, builds, operates everything the simplest way. Keep it simple, it is more reliable, it breaks down less often, but when it does, it is simpler to fix it.