Author Topic: Saturn helium usage  (Read 13052 times)

Offline ka9q

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Saturn helium usage
« on: December 29, 2014, 04:40:38 AM »
One thing that strikes me when I look at the Saturn launch vehicle designs is the enormous amount of helium they used for purging and pressurization, particularly of fuel tanks (gaseous oxygen seems to have been used for pressurizing the LOX tanks).

Besides its light weight, helium does have the unique property of remaining gaseous even at liquid hydrogen temperatures, allowing it to be stored in spheres inside the LH2 tank in the S-IVB, for example.

But anybody who has tried to get helium lately for saturation diving, welding, filling balloons, etc, knows just how bloody scarce and expensive the stuff has become. This is not actually a big surprise since it's a limited, non-renewable resource (on human timescales, anyway) and we've been using the stuff pretty indiscriminately.

I suppose helium is still acceptable in smaller pressure-fed hypergolic engines on spacecraft, but using huge amounts in launch vehicles seems like a real sustainability problem. Does anybody know if modern space launch vehicles still use it to the degree that the Saturns did?



Offline Luke Pemberton

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Re: Saturn helium usage
« Reply #1 on: December 29, 2014, 12:27:27 PM »
One thing that strikes me when I look at the Saturn launch vehicle designs is the enormous amount of helium they used for purging and pressurization, particularly of fuel tanks (gaseous oxygen seems to have been used for pressurizing the LOX tanks).

Besides its light weight, helium does have the unique property of remaining gaseous even at liquid hydrogen temperatures, allowing it to be stored in spheres inside the LH2 tank in the S-IVB, for example.

But anybody who has tried to get helium lately for saturation diving, welding, filling balloons, etc, knows just how bloody scarce and expensive the stuff has become. This is not actually a big surprise since it's a limited, non-renewable resource (on human timescales, anyway) and we've been using the stuff pretty indiscriminately.

I suppose helium is still acceptable in smaller pressure-fed hypergolic engines on spacecraft, but using huge amounts in launch vehicles seems like a real sustainability problem. Does anybody know if modern space launch vehicles still use it to the degree that the Saturns did?

I have to admit that I've never thought about this problem in the wider context of helium in science and engineering. I found an interesting BBC article that asks about the use of helium in party balloons.
« Last Edit: December 29, 2014, 01:29:00 PM by Luke Pemberton »
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former - Albert Einstein.

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A polar orbit would also bypass the SAA - Tim Finch

Offline ka9q

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Re: Saturn helium usage
« Reply #2 on: December 29, 2014, 06:06:46 PM »
I'm familiar with the helium problem because I help mentor a local high school ham group that builds and flies payloads under weather balloons. We only use a few cubic meters of helium per flight, but even that has gotten hard to find and outrageously expensive -- on the order of hundreds of dollars.

So we're doing what many other groups are doing: we're switching to hydrogen. Everybody fears the stuff, but nobody can point to an actual accident to justify their fear. I did find a Youtube video of a university group deliberately igniting a hydrogen-filled weather balloon as a safety test. The results were actually rather underwhelming as the hydrogen rose above the balloon before burning in an orange-ish "whumph". The only likely hazard to people on the ground seemed to be the falling bits of flaming latex.

Seems to me that handling hydrogen is at least as safe as handling gasoline, probably more so as long as you work outdoors and take reasonable precautions. There's an inexhaustible supply, so switching to it does seem like an ethical imperative. And it's an even better lifting gas than helium.
 

Offline Glom

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Re: Saturn helium usage
« Reply #3 on: December 30, 2014, 01:42:21 PM »
It's only a quarter of the visible matter in the universe. It's like talking about hose pipe bans while Wiltshire is flooded.

Offline Allan F

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Re: Saturn helium usage
« Reply #4 on: December 30, 2014, 02:21:27 PM »
Yes, it is common in the universe, but hard to get hold of in our corner.
Well, it is like this: The truth doesn't need insults. Insults are the refuge of a darkened mind, a mind that refuses to open and see. Foul language can't outcompete knowledge. And knowledge is the result of education. Education is the result of the wish to know more, not less.

Offline ka9q

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Re: Saturn helium usage
« Reply #5 on: December 30, 2014, 06:33:28 PM »
Yes, it is common in the universe, but hard to get hold of in our corner.
Exactly. Just like hydrogen in its elemental state. If it were easy, our energy problems would be over.

Offline Glom

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Re: Saturn helium usage
« Reply #6 on: December 31, 2014, 06:37:45 AM »
What bad luck.

Offline ka9q

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Re: Saturn helium usage
« Reply #7 on: January 02, 2015, 05:10:14 PM »
What bad luck.
We're actually lucky that hydrogen is so reactive, and that virtually all of it on earth is chemically combined in some way. Otherwise it would be as scarce as helium. Or more, since I don't know of any nuclear decay processes that produce it.

Offline Obviousman

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Re: Saturn helium usage
« Reply #8 on: January 03, 2015, 07:12:47 AM »
It has been suggested that shortly helium will be vastly more expensive, due to the dwindling supply. The remaining supplies will be dedicated to scientific and strategic uses.

Helium balloons and the accompanying "Mickey Mouse" voices may very soon be a thing of the past..

Offline Luke Pemberton

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Re: Saturn helium usage
« Reply #9 on: January 03, 2015, 08:51:50 AM »
Helium balloons and the accompanying "Mickey Mouse" voices may very soon be a thing of the past..

In years to come we will show our grandchildren YouTube videos of people on helium and say 'in my day we did that at parties.'
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former - Albert Einstein.

I can calculate the motion of heavenly bodies, but not the madness of people – Sir Isaac Newton.

A polar orbit would also bypass the SAA - Tim Finch

Offline Glom

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Re: Saturn helium usage
« Reply #10 on: January 03, 2015, 06:25:11 PM »
There is only one option. We need to seriously start making fusion happen. For the sake of children parties.

Offline cjameshuff

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Re: Saturn helium usage
« Reply #11 on: January 07, 2015, 06:35:43 PM »
It has been suggested that shortly helium will be vastly more expensive, due to the dwindling supply. The remaining supplies will be dedicated to scientific and strategic uses.

Helium balloons and the accompanying "Mickey Mouse" voices may very soon be a thing of the past..

Hydrogen would work even better for the squeaky voices, if you're okay with the possibility of exploding.

Offline Allan F

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Re: Saturn helium usage
« Reply #12 on: January 07, 2015, 06:50:08 PM »
Smoking and hydrogen usage is not recommended.
Well, it is like this: The truth doesn't need insults. Insults are the refuge of a darkened mind, a mind that refuses to open and see. Foul language can't outcompete knowledge. And knowledge is the result of education. Education is the result of the wish to know more, not less.

Offline ka9q

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Re: Saturn helium usage
« Reply #13 on: January 08, 2015, 05:55:11 AM »
Hydrogen would work even better for the squeaky voices, if you're okay with the possibility of exploding.
Correct.

Interestingly enough, breathing mixtures of hydrogen and oxygen are sometimes used in very deep diving. It's actually safe because the high pressure allows the oxygen percentage to be below the flammability limit (about 4%, IIRC) while still providing a sufficient ppO2 for breathing. In fact there's an important physiological reason to keep the O2 percentage down at high pressures: too much oxygen is quite toxic.

At shallower depths the O2 fraction would have to be higher, making the mixture quite explosive. So the more familiar helium/oxygen mixtures must be used instead.
« Last Edit: January 08, 2015, 05:57:04 AM by ka9q »

Offline Chew

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Re: Saturn helium usage
« Reply #14 on: January 09, 2015, 03:08:35 PM »
Google's Project Loon is sucking up the helium.

Their balloons have transponders on them so they show up on Flightradar24 as screencapped below. Google launched 10 balloons in mid-Dec, 7 from New Zealand and 3 from California. The California launches traversed across the entire contiguous US. One flew 5 miles north of my house. I stuck my iPhone camera up to my binoculars to get a pick (second pic link below). Google assigns them callsigns starting with "HBAL". In Flightradar24 you can add that as a callsign filter so the website will only display Project Loon balloons (if they are in flight). They sometimes generate UFO reports.

Project Loon - Wikipedia, the free encyclopedia

http://www.flightradar24.com/-0.85,-109.3/2

http://i.imgur.com/7E9toHO.jpg

http://i.imgur.com/wtJnX4h.jpg