A Noble Gas
By Larry Larason
Here’s a good trivia question: Which chemical element was discovered before anyone knew it existed on Earth? That seems impossible, doesn’t it? Scientists usually found an element, studied it in their laboratories, and then announced the discovery. Helium was different.
So where was this element discovered? Its name gives a hint: On the sun. How was it discovered? By spectroscopy. When chemicals are heated to incandescence they emit light in specific wavelengths of the color spectrum. Each element has a unique spectral signature, like a fingerprint, for that element. In 1868 two scientists observed the sun and spotted new spectral lines. The French scientist, Jules Janssen, had traveled to India to observe a solar eclipse; he spotted a yellow signature line in his spectroscope when he focused on the solar corona during the eclipse. Norman Lockyer observed the same thing from England later that same year while he observed the sun through cloudy, smoky skies. Lockyer knew it was a new element, which he assumed existed only on the sun. He named it helium in honor of the Greek god of the sun, Helios. The “-ium” ending implies the element is a metal, which Lockyer believed, but it is not metallic. It is a noble gas, like neon, argon, krypton, xenon and radon, all of which appear in the right most column of the periodic table of the elements. All the noble gases are inert; they are known for being very unlikely to form chemical compounds.
Hydrogen is the lightest element. Helium is the second. Helium is so light weight that gravity hardly affects it. The helium in our air gradually drifts to the top of the atmosphere and escapes into space. Hydrogen might do the same except it is highly reactive; it joins in compounds readily. Helium is too aloof – “noble” – to join in combinations with other elements; it nearly always exists only as single atoms.
Two independent teams of scientists in 1895 found helium on Earth in uraninite, an ore of uranium. Alpha radiation issued when uranium and thorium decay is simply the emission of particles that are helium nuclei.
Everyone thought that helium was very rare on Earth. Then something happened in Kansas. Today Dexter, Kansas is a small town of 278 people, famous for being where the Dalton Gang pulled their last successful bank robbery in 1892. Its more important claim to fame happened in 1903 and brought it international attention . . . for a few years. A well had been drilled in search of oil. But what they found was described as “a howling gasser.” The noise of the escaping gas could be heard for miles around. Everyone thought the future of Dexter was assured, that industry would soon move in to utilize the natural gas. A celebration was organized. On that day a crowd gathered, the band played, speeches were made. Then the town fathers planned to set fire to a jet of gas providing a pillar of flame for a day and a half.
He ignited a bale of hay and pushed it toward the gas vent. The fire went out. They tried again. The fire went out again. They tried several times, but the gas extinguished the flames every time. They finally had to concede that their gas would not burn. You can imagine their chagrin.
Erasmus Haworth, the state geologist of Kansas, was in the crowd that day and took a canister of the gas back to the University of Kansas to analyze. He and a chemist colleague found that the gas contained about 15 percent methane, and another 72 percent nonflammable nitrogen. The remaining 12 percent baffled them for a time, but using a spectroscope they found that it was partly helium. This put Dexter on the map as the place that proved helium was not a rare element on the Earth.
Two questions often occur about helium. First: Why is there helium on the Sun? Hydrogen fusion, which powers the Sun, produces helium. A helium atom is essentially a doubled hydrogen atom. Second: How does a gas so light that it floats to the top of the atmosphere and escapes to space come to be underground? Some of it was primordial; that is, it was incorporated in our planet along with the heavier elements when the Earth formed. However, it is being created continuously by the breakdown of radioactive elements. The basement rocks beneath the continents are mostly granites, and almost all granites contain some uranium and thorium, which are radioactive, and spit out helium nuclei. The helium creeps upward through faults and fractures in rocks until it encounters an impermeable layer where it becomes trapped.
The Four Corners has a lot of helium. At the Rattlesnake Oil Field, which I wrote about last month, helium was found in the gas from a well drilled in 1942. This was the first helium produced in the Four Corners. It has also been produced from the Dine bi Keyah field in the Chuska Mountains; one well there had 4.2 percent helium. There were helium processing plants near Shiprock for a couple of decades. Production in San Juan County ceased about 1990. Some of the world’s richest helium wells were found in the Holbrook Basin, which produced helium in the 1960s-1970s. Kerr McGee built a helium plant in the area, but after declining production the plant and wells were abandoned in 1976. Gas containing helium is considered commercial if the helium content is better than 0.3 percent. One well drilled on the Pinta Dome in Arizona tested at more than 8 percent.
This noble gas is about more than party balloons, which use about 8 percent of the supply. About a quarter of the helium used in the US cools magnets in MRI machines. It also cools magnets in particle accelerators, such as the Large Hadron Collider. It’s used in welding and several manufacturing operations. Scuba divers use it in part to produce a breathing gas for deep diving.
Thinking primarily of blimps and dirigibles, the US established a strategic reserve of helium in abandoned gas wells near Amarillo, Texas in 1925. Lighter-than-air-crafts never became important, but new uses of the gas were found, especially to cool the liquid oxygen and hydrogen fuels of the Apollo spacecrafts during the 1950-1960s.
At that time the reserve was expanded, but by 1995 Congress, appalled by the $1.4 billion debt incurred by the operation, voted to have the BLM sell off the gas and close the installation by 2015. Today the reserve program supplies about one-third of the world’s helium each year, and while sales have increased, helium production is dropping. The supply issue has become so critical that many scientists have proposed rationing the gas to preserve it for important scientific uses. Our own Senator Jeff Bingaman was a leader in the effort to preserve the plant at Amarillo. So far Congress has not acted, but with the known reserves of helium in the Four Corners we might see some development in the future.