NASA researchers have for the first time suspended tiny chunks of solid hydrogen in liquid helium, an important step in the development of a rocket fuel that would revolutionize space flight.

While more than a decade away from being used in rockets, the fuel would multiply the power of rockets by a factor of three or more.

The International Space Station, now sent up piece-by-piece in 46 launches, could theoretically be carried in a single rocket launch with the new fuel, according to Bryan Palaszewski, the principal investigator for the experiment.

Extremely cold chunks of solid rocket propellant would be infused with hydrogen atoms and dropped into a bath of liquid helium. As the solution heats up, the hydrogen atoms would jump together to form molecules, giving off a tremendous amount of heat that would then vaporize the rocket propellant.

The force of the reaction -- many times more powerful than that of the current method -- would send the rocket hurtling into space.

"Explosion is an understatement," Palaszewski said. "This could potentially be quite dangerous."

The fuel could also be used to make very powerful bombs, according to Palaszewski.

While the finished version is years away, scientists at NASA's Glenn Research Center in Cleveland, Ohio have made a prototype. The project is sponsored by NASA and the U.S. Air Force.

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

The next step, infusing the propellant with hydrogen atoms, poses a considerable problem.

Hydrogen atoms exist naturally in pairs, and can only be kept apart in extremely cold environments where movement is nearly impossible.

With today's technology, the density of hydrogen atoms in the propellant must be kept very small -- one-tenth of one percent -- or else molecules start to form.

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

A practical rocket fuel would have hydrogen atoms in the proportion of around 10 or 20 percent of the solution, Palaszewski said.

Air Force scientists are also experimenting with other atoms, like boron and carbon. Those atoms are less reactive in their solitary states than hydrogen, but would increase the weight of the fuel.

The process of recombining atoms to produce energy has been considered by scientists for over 60 years, Palaszewski said. But the process still has 10 or 20 years of development to go through before practical use, he added.

The liquid helium used in the prototype was cooled to 4 degrees Kelvin (minus 452 degrees Fahrenheit). That is just barely above the point of absolute zero -- a temperature which represents the total absence of heat.

While absolute zero is currently unattainable, scientists have been able to cool objects to just a fraction of a degree. At those temperatures, even greater densities of atomic hydrogen -- and even greater power -- are possible.