Revolutionary Rocket Fuel

Was cruising the internet and found this amazing article.

www.space.com...

This is what I'm talking about I mean take the shuttles payload capacity which I believe is about 23 tonnes. Now multiple that by a factor of three. Wow 12,167 tonnes. Or a Saturn 5 heavy lift vehicle 130x130x130, 2,197,000 tonnes to LEO. Practically the same lifting power as an Orion nuclear pulse rocket:

This is probably what they'll use in the proposed 100 ton super heavy-lift rocket.

I believe the stuff the USAF is working on (for ballistic missiles) is called HEDM High Energy Density Matter. Basically a leap ahead of the next generation of propellants.

How are the engineers going to use this? Getting hydrogen to its liquid form is work enough and so is containing it, but solid hydrogen? I wonder what the freezing point is, though it would be cool to look at the tiny bits under the microscope. I ahve heard that some scientist believe solid hydrogen exist as a metal in the core of Jupiter.

They do state that the helium must be maintained at 4 K, to me it sounds like it will take a large freezing unit to contain all that mess, using lasers would seem very eneffeicient for this.

Still many questions out there.

But as scientists develop ways to make the solution colder and engineer specialized, reaction-resistant atomic structures, that density can increase.

I am assuming that this means the molecules will prevent any heating of the hydrogen and allow a larger density. But this seems like it will only increase the weight of the propellant.

Though I guess I will be surprized when we start using these things as rocket propellants, which I guess means good-bye lox.




[edit on 10-11-2005 by Frosty]

Originally posted by Frosty
How are the engineers going to use this? Getting hydrogen to its liquid form is work enough and so is containing it, but solid hydrogen?

Getting molecular hydrogen solid is not a problem, happens at 20K, and hence the "achievement" in the article does not seem impressive at all. They didn't try yet with atomic hydrogen, which would be quite more impressive.

Originally posted by Frosty
I ahve heard that some scientist believe solid hydrogen exist as a metal in the core of Jupiter.

That's solid metallic hydrogen, a different hydrogen state from the covalent bound H2 molecules they're normally in. The energy of that state would also be enormous, but noone knows whether it is metastable (=like diamond, can also exist at atmospheric pressures) and that is a different issue alltogether.

Originally posted by Frosty
I am assuming that this means the molecules will prevent any heating of the hydrogen and allow a larger density. But this seems like it will only increase the weight of the propellant.

The density of solid molecular hydrogen is only marginally larger than liquid hydrogen, which is why some would like to use slush hydrogen as propellant. What it actually means is simple. Atomic hydrogen is extremely reactive, and like almost all chemical reactions, the reaction rate slows when the temperature decreases. If the temperature is too high, atomic hydrogen could recombine into hydrogen molecules, giving off energy increasing temperature, which makes more atomic hydrogen recombine, and before you know it, you have a chain reaction and your tank explodes.

So basically, what you want to do to avoid this is:

1. Cool the atomic hydrogen as much as you can to decrease reactivity
2. Try to avoid atomic hydrogen atoms from running into each other.

For the second point, one possible solution is to dissolve it into a liquid, so the hydrogen atoms have a higher chance of running into inert helium atoms with no consequences than they have a chance of running into other hydrogen atoms with the possible consequence of recombining and giving off its energy into the tank prematurely and not in the rocket engine. You do not want however to get your hydrogen too dissolved as otherwise you have too much helium as useless dead weight in your tank. So those are conflicting demands making the problem very difficult.

Another possible solution could be too embed the hydrogen atoms into a solid, like solid molecular hydrogen, as to beef up ordinary hydrogen. This would avoid atomic hydrogen recombining, since in a solid the atoms and molecules stay pretty much in the same place. Problem with that is how will you get it into the solid as molecular hydrogen only solidifies at around 20K while your atomic hydrogen is pretty reactive then. Plus you can't pump solids, so how would you get it from the tank to your engines if you can't use pumps?

Another possible solution is to add stabilizer so that IF the hydrogen atoms recombine, they give off their energy to the stabilizers and not to other hydrogen atoms with the risk of taking them along, which raises the temperature you can safely keep them together before a chain reaction occurs and lowers reaction rate. Problem with this is what will you use at these low temperatures as stabilizer, plus that the stabilizer will once again add weight.

So that is more like what they mean with reaction-resistant atomic structures and which illustrates the enormous technical difficulties associated, which is why I believe this will never get anywhere.

Originally posted by Simon666
Getting molecular hydrogen solid is not a problem, happens at 20K, and hence the "achievement" in the article does not seem impressive at all. They didn't try yet with atomic hydrogen, which would be quite more impressive.

Forgive me if I'm wrong Simon but it sounds to me that that is what there trying to do.

Extremely cold chunks of solid rocket propellant would be infused with hydrogen atoms and dropped into a bath of liquid helium.

Originally posted by Simon666
The density of solid molecular hydrogen is only marginally larger than liquid hydrogen, which is why some would like to use slush hydrogen as propellant. What it actually means is simple. Atomic hydrogen is extremely reactive, and like almost all chemical reactions, the reaction rate slows when the temperature decreases. If the temperature is too high, atomic hydrogen could recombine into hydrogen molecules, giving off energy increasing temperature, which makes more atomic hydrogen recombine, and before you know it, you have a chain reaction and your tank explodes.

Yes that is the problem thats why you freeze the hydrogen molecules to a temerature were when infused with atomic hydrogen the reaction rate is reduced to an inert state.

Originally posted by Simon666
Another possible solution could be too embed the hydrogen atoms into a solid, like solid molecular hydrogen, as to beef up ordinary hydrogen. This would avoid atomic hydrogen recombining, since in a solid the atoms and molecules stay pretty much in the same place. Problem with that is how will you get it into the solid as molecular hydrogen only solidifies at around 20K while your atomic hydrogen is pretty reactive then.

That sounds exactly to me what they are doing. Now as far as the reactive state of atomic hydrogen know one said you had to stop at 20K did they?

Originally posted by Simon666
Plus you can't pump solids, so how would you get it from the tank to your engines if you can't use pumps?

Remember its in a bath of liquid helium.

Originally posted by danwild6
Forgive me if I'm wrong Simon but it sounds to me that that is what there trying to do.

Extremely cold chunks of solid rocket propellant would be infused with hydrogen atoms and dropped into a bath of liquid helium.

It is what they ultimately would like to do. Note that in the fragment you quoted it says "would be". What they actually accomplished thus far and which is according to me not that impressive, is:

They have suspended about 10 grams of the frozen propellant -- which is actually hydrogen molecules -- into about three liters of liquid helium.

So they haven't even begun trying to actually work with atomic hydrogen.

Originally posted by danwild6
Remember its in a bath of liquid helium.

I was just illustrating the problems with trying different approaches to use atomic hydrogen, that it isn't that simple.

Originally posted by danwild6
That sounds exactly to me what they are doing. Now as far as the reactive state of atomic hydrogen know one said you had to stop at 20K did they?

It doesn't sound exactly like what they are doing. It sounds like exactly what they want to do. I'd want sex with Angelina Jolie but my chances on it are pretty slim. Maybe they'd like to get atomic hydrogen in solid hydrogen afterwards as next step, but I don't think that would be that easy for the reason I've cited.

Originally posted by Simon666So that is more like what they mean with reaction-resistant atomic structures and which illustrates the enormous technical difficulties associated, which is why I believe this will never get anywhere.

Ok, thanks. I thought they were trying to add a whole new molecule (element) to the hydrogen to act as a barrier from unwanted chemical reactions, like the way carbon bonds act within biological substances, not to say they don't have other functions.

There are metal fuels: www.newscientist.com...

So would it be possible to add metallic hydrogen to liquid helium and make it more reactive? Or would a ionic bond not be good enough to create as much energy as that found in the non-metallic solid hydrogen?

Here's some more info on this and some other interesting projects.

www.grc.nasa.gov...

Plus you can't pump solids, so how would you get it from the tank to your engines if you can't use pumps?

If said porous solid confined the Hydrogen in the matrix at a decent temperature could you not engineer the solid to 'excrete' the hydrogen under certain artificial environments like say a vacuum?

Here's the report on the initial stages of development.

www.grc.nasa.gov...

Found another link with some more up to date information.

www.grc.nasa.gov...

Yet another link.

sbir.grc.nasa.gov...