You may not know much about helium, except that it fills birthday balloons and blimps and can make even the most stentorian voice sound a bit like Donald Duck.

But helium is an important gas for science and medicine. Among other things, in liquid form (a few degrees above absolute zero) it is used to keep superconducting electromagnets cold in equipment like M.R.I. machines and the Large Hadron Collider at CERN, the European Organization for Nuclear Research, which uses 265,000 pounds of it to help keep particles in line as they zip around.

Helium’s role in superconductivity and other applications has grown so much that there have been occasional shortages. The gas forms in nature through radioactive decay of uranium and thorium, but exceedingly slowly; in practical terms, all the helium we will ever have already exists. And because it does not react with anything and is light, it can easily escape to the atmosphere.

Until now, it has been discovered only as a byproduct of oil and gas exploration, as the natural gas in some reservoirs contains a small but commercially valuable proportion of helium. (The first detection of helium in a gas field occurred in the early 1900s when scientists analyzed natural gas from a well in Dexter, Kan., that had a peculiar property: It would not burn.)