Noble gas

Ever wondered how many helium balloons it would take to lift yourself off the ground? If sanity has kept you from finding out, you'll enjoy Jeff Whitehead's video of a safely tethered helium flyer in the crucial experiment (humanbeingcurious.com/page17/page16/ page16.html). The results would have been more dramatic, however, if the pilot had cut her tethers to drift free, as "Lawn-Chair Larry" did in 1982 (go to markbarry.com or to darwinawards.com/ darwin to read that remarkable story). More recently, John Ninomiya, a licensed hot-air balloon pilot, has made about forty such flee-flying helium-powered flights (go to clusterballoon.org to find out more).

Given the rarity of helium on earth, using the noble gas for filling a party balloon seems just, well, frivolous. Making up just 0.0005 percent of the atmosphere, helium is so diffuse it wasn't detected until 1868, and then only from a mysterious line in the solar spectrum. For that reason, Sir J. Norman Lockyer, a British astronomer, named it after Helios, the Greek sun god. Go to "Astronomy Picture of the Day" at antwrp.gsfc.nasa.gov/apod/ap960520.html to see our star glowing in the light emitted from hot, ionized helium.

Modern astronomy has revealed that helium is the second most common element in the universe, after hydrogen, making up nearly a quarter of the mass of visible matter. An entertaining Web site called "The Big Bang Time Machine" (schoolscience.co.uk/flash/bang.htm) takes you back to the earliest moments of the universe, when, among other things, hydrogen and helium condensed into being after the big bang's burst of incredible heat. (Use the time machine's green joystick to go back and forth.) A Web page at the University of Tennessee Astrophysics Group (csep10.phys.utk.edu/astr162/lect/ cosmology/hotbb.html) details how the formation of helium supports the big bang model. For basic information about helium, go to theodoregray.com/ PeriodicTable/#tabletop and click on the symbol "He" at the upper right. In addition to making the most beautiful periodic table on the Internet, Theodore Gray has collected fascinating specimens of the elements, which you can view by scrolling down the page for each one

For eighty years almost all of the world's extracted helium has come from the natural-gas fields around the Oklahoma panhandle. Compared with the cosmic helium, the Oklahoma helium is relatively young, a by-product of radioactive decay deep within the earth. Until recently the U.S. government stockpiled excess helium in an underground reservoir near Amarillo, Texas. The National Academy of Science has an excellent overview of the helium supply--past, present, and future--in an online report at darwin.nap.edu/books/ 0309070384/html titled "The Impact of Selling the Federal Helium Reserve."

Chapter three describes the unique properties that make the gas indispensable to modern technology. Remaining liquid down to absolute zero (at least at ordinary pressures), helium is critical to many devices that require extreme cold--such as the powerful superconducting magnets in MRI imaging machines, which consume about a third of the gas now collected. And because helium does not react with other elements, it is used for making controlled atmospheres, for pressurizing, and for purging in many industrial processes, as well as for welding and for gas mixtures that deepwater divers can breathe safely.

Because pure helium gas can slip through holes that would stop any other gas (that's the reason helium balloons go flat so quickly), it is a common leak detector. An article from the Houston Geological Society (hgs.org/ en/art/?162), titled "Helium Exploration--A 21st Century Challenge," gives more insight on meeting the growing demand for this noble gas.

In the more distant future, helium might help solve one of humanity's most pressing problems: how to supply abundant energy without increasing greenhouse gases or poisoning the environment with radiation. The key may be helium-3, a rare isotope on Earth, but which occurs in abundance in lunar soil (see the article in Wired magazine titled "A Helium Shortage?" at wired.com/wired/archive/8.08/helium. html). As a fuel for fusion reactors, helium-3 could, in principle, provide limitless energy, with little residual radiation. Harrison H. Schmitt, the only geologist to step on the Moon, is a proponent of returning there someday to mine it for helium. To listen to him lecture on the subject, go to Google's video search engine (video.google.com) and type in "Schmitt helium," or try mitworfd.mit.edu/video/159 for a more lengthy presentation. If his dreams are ever realized, helium will be a noble element indeed