Helium beneath my wings
Sunday, April 21, 2019
It’s a one-way journey for helium, but a round trip for the ant-watchers.
Every day, a worldwide fleet of 1,800 balloons launches into the atmosphere for the sake of weather science and data reliance.
It’s a daily space race.
In this era of drones and rocket ships, balloons filled with helium seem like old-fashioned oxen that plow Earth’s crown and ply the wild sky. But cheap balloons can ascend above the clouds, above stones and drones, above jets and jetstreams, to where the air is barely there. Each balloon carries instrument probes and transponders, sipping conditions and blipping positions while zipping an up-tripping mission. The information aloft provides air-truth to the mathematical models that predict the weather.
The balloons vie to fly the highest sky. Blimps and party balloons, and amatuer research balloons carrying cameras capturing sky-eye views of wee-land and ant-man, compete for helium and altitude while the steadfast oxen slog the smog.
Each balloon carries instruments in a dangling little box, streaming data back to receivers on Earth. When the atmosphere thins to about one percent of its density here on the ground, the balloon pops, casting rubbery shards outward to drift down, and the dangling box parachutes to the ground. But the gas in the balloon goes up.
Many weather balloons are filled with hydrogen, mini-Hindenburgs carefully inflated, then let go to drift upward because hydrogen, the lightest of all elements, floats in air like an oil bubble floats in vinegar; like a glass bottle corked with air defies the weight of the glass. Other balloons are filled with helium, the second lightest gas.
Both helium and hydrogen are destined for outer space. At the top of the atmosphere, liberated by the balloon burst, they drift up and away from Earth, never to return. Unlike our oxygens and nitrogens that mostly stick around forever, hydrogen and helium are here as temporary inhabitants. Earth’s first hydrogen molecules, left on their own, have already flown away. The hydrogens in balloons had to be pried off other substances, and once released, they will either recombine or float away.
Helium only floats away.
Most of the helium in the universe, our best scientific guess tells us, developed in a brief but spectacular 20-minute period billions of years ago when the entire universe resembled the fusion core of a star, bubbling hydrogen into helium, but the universe cooled to a non-thermo-nuclear temperature before the bigger elements could develop. Since then, most new helium in the universe has come from actual stars — giant stars, sun-like stars, barely glowing dwarf stars — that yield the majority of their starshine cooking hy into he.
On Earth, our universe-helium drifted away long ago. But the Earth expels its own tiny fraction. Radioactive metals deep within the core emit first-time helium: as radioactive uranium and thorium self-destruct, helium nuclei come flying out, sucking off a pair of electrons from some unwitting donor ions on the way. These brand-new helium atoms bubble out of Earth’s core and float for the top. But many heliums are trapped inside Earth by airtight rock layers. The Earth, it turns out, itself resembles a mostly solid balloon with a wisp of gas trapped inside our sphere’s veneer.
Puncturing the veneer restores the long helium journey from near the floor of the Earth’s hot core to tanks of helium in the back of a truck, to the nozzle of a balloon.
As the balloon races for the surface of the sky, the air thins and the thick-packed balloon expands, hard-pressed to hold in the helium, eventually stretching the walls to the popping point. Shards sprinkle, the instrument package parachutes to Earth, and the helium — 0h, the helium! — pfizzles to space, gone forever from Earth’s reserves, cast adrift in the emptiness of primordial space.
Dad loved to fly up there where the balloons with their helium play, and he had his private pilot’s license. When I was 8 years old, he took me up in a rented plane, and we flew to Massachusetts and back from our local airport in New York, just for the fun of seeing specks of ant cars driving along threads of ant roads.
On the way back, at 90 mph over Pittsfield, he said to me, “Ok, you drive.” I sat there, wide-eyed, and neither of us drove — nobody had a hand on the wheel — for a few minutes. Cautiously, I touched the handlebar that passes for a wheel that pilots dismiss as a stick. That was all there was to it. I was not only flying, I was flying with one finger. Boy, I’d have to swagger that in front of my brother.
I didn’t think to look around for balloon shards or helium. The ants were too distracting.
Follow @jmoseshall on Facebook. Joy Moses-Hall teaches physics and astronomy at Pitt Community College. She has a PhD in oceanography and is the author of the novel Wretched Refuge.