99 luftballoons

It's been one of those weeks where I feel just like Robert Niro's anxiety-ridden mob boss in Analyze This. Granted, I'm just juggling my usual round of deadlines with book promotion; selling my DC condo; scouting around for a wedding venue; preparing for next week's lecture/martial arts demo in NYC; compiling year-end tax forms and receipts; and beginning to pack up the "nonessentials" in anticipation of my pending cross-country move. (I accidentally ordered the industrial-sized roll of bubble wrap, which now threatens to engulf my living room.) De Niro was dealing with panic attacks brought on by an upcoming "gangsta summit", the threat of a hostile (and potentially fatal) takeover, and the murder of a close friend whose death brought up long-repressed memories of witnessing his own father's murder. Complaining to Billy Crystal's long-suffering psychiatrist about the negative impact this was having on his emotional well-being, De Niro whimpers, "I got stress!"

My stress factors are more positive than that fictional gangster's myriad problems -- "Everyone should have your problems!" scoffs my pal Lee -- but then, I don't pop a few caps into innocent throw pillows to relieve the tension, either. Still, by yesterday afternoon, I was an extremely tightly wound ball of pent-up nervous energy. Yeah, baby, I got stress. So I took the night off, turned off the computer, and vegged out in front of the TV for a couple of hours before retiring early. Clifford at Asymptotia calls this "de-gaussing." What a great term -- I did feel like my body had all these trapped magnetic fields that had built up to very high levels over the course of the week. A few hours of mindless leisure and a good night's sleep successfully dispersed ("de-Gaussed") them.

Clearly I've been a bit preoccupied of late, which is why (a) I haven't been blogging that much, and (b) I missed the December 21 launch of NASA's Balloon-borne Large-Aperture Sub-millimeter Telescope, or BLAST. (Insert your own "BLAST off" joke here.) It's probably already landed by now. But I'm blogging about it anyway, because I love NASA's balloon-borne program. For all the high-tech rocketry that drives the space shuttle program, a lot of really fascinating science can be done using hot-air balloons, a technology that is more than 300 years old. For instance, for astrophysicists interested in collecting and analyzing X-ray and gamma ray emissions from celestial objects, much of that radiation is absorbed by the Earth's atmosphere, and thus never gets through to ground-based detectors. Mounting their equipment onto helium-filled balloons gets the instruments above that atmosphere, and the radiation they detect should help scientists get a better picture of star formation in distant galaxies, among other insights. It's much cheaper and faster than sending a manned starship out to the "mind-blogging edges of the universe to watch and study cosmic childbirth firsthand," as The Antarctic Sun so poetically phrased it.

Initially, ballooning had far less cosmic aspirations. In 18th century France, Joseph Montgolfier, the recalcitrant son of a successful papermaker noticed that laundry drying over the fire tended to form pockets in the fabric that billowed upwards. He didn't think much of it at the time (most accounts peg the year as 1777), because he was far too busy rebelling against familial expectations. Still, despite loathing formal education -- Wikipedia reports that he ran away from school twice -- he managed to cobble together a reasonably competent self-education in the physical sciences. While living in Avignon in 1782, he found himself in front of a warm, cozy fire, wondering if the same force that lifted the embers from the fire could be used to mount an air assault on, say, the fortress of Gibraltar, which had thus far proved unbreachable by land or sea.

Joseph built a boxy frame out of thin wood and covered the top and sides with lightweight taffeta, then crumpled up some paper underneath and lit it. As the paper burned, his homemade contraption lifted off its stand and hit the ceiling. He probably uttered the French equivalent of "Eureka!" And he promptly recruited his brother Etienne to develop the concept further: "Get in a supply of taffeta and of cordage, quickly, and you will see one of the most astonishing sights in the world!"

Joseph was a bit off base at developing an explanation for the effect: he believed the smoke from the fire contained a special "Montgolfier gas," and dubbed its buoyant property "levity." In reality, the hot air inside expanded, and thus weighed less, by volume, than the surrounding air. Okay, that's a bit overly simplistic. If you want to be more specific, it has to do with the properties of trapped gas, specifically, temperature, pressure and volume. The number of atoms inside the balloon doesn't change when it's heated (or cooled, for that matter). Rather, the gas expands and the balloon's volume increases so that its internal pressure remains in balance with the surrounding air pressure, and that volume shrinks as the gas cools -- again, to maintain the pressure balance. This is something that's familiar to anyone who's watched the deflation of mylar balloons when taken outside in cold weather, only to seem to blow back up again when it is brought safely back to a warm indoor environment. (Still craving details? Physics Central has more specifics right here.)

Back to the Montgolfier brothers: within a month they had built and successfully tested a much larger version of the contraption, and decided to conduct a public demonstration of their invention, which they did on June 4, 1783. A few months later, the brothers' "Aerostat Reveillon" demonstrated balloon flight once again before a huge crowd at Versailles that included King Louis XVI and Marie Antoinette. It also carried passengers: specifically, a duck, a sheep, and a rooster. (In fairness, I should note that a few aviation historians credit a Portuguese priest named Bartolomeu de Gusmao with the invention of the hot air balloon as early as 1709. But this is hotly disputed.)

As a result of these sorts of whizz-bang demonstrations (see? public demos work!), ballooning became all the rage in late 18th century France. In fact, in 1785, John Blanchard made the first aerial crossing of the English channel in a hot air balloon. By the mid-19th century, however, ballooning had given way to the dirigible (airship) craze, enormous envelopes shaped like a cigar and filled with hydrogen, a gas that is lighter than air at normal temperatures, thus dispensing with the need to heat the internal gas. (Of course, as the Hindenburg disaster aptly demonstrated in 1937, dirigibles had their own drawbacks.)

Today, there's all kinds of weather balloons deployed in the atmosphere, feeding back vital information on atmospheric pressure, temperature and humidity. Outfitted with a tracking device, they can even yield useful wind data. And last year, the National Center for Atmospheric Research (NCAR) launched a long-awaited weather observation platform called a driftsonde -- essentially a caravan of balloons carrying dropsonde weather instruments that drifts through the atmosphere collecting data, strewing its payload of dropsonde instruments along the way. NCAR has been testing prototypes since the 1970s, when scientists first developed instrument packages capable of surviving the harsh conditions in the stratosphere. But the end result was to bulky and heavy; thanks to three subsequent decades of exponential miniaturization in the electronics industry (and elsewhere), driftsondes are now a reality. Launched from an airport in Zinder, the second-largest city in Niger, on August 28, the very first driftsonde to be deployed wafted its way across the Atlantic, followed over the next month by seven other driftsondes.

It was probably just a matter of time before NASA realized the scientific potential of balloons as a cost-effective means of exploring space, including other planets. For instance, solar-heated balloons could be used instead of conventional parachutes to lower spacecraft to a planet's surface while conducting aerial photography. The Jet Propulsion Laboratory has an extensive research program in this area. In 2003, University of Chicago scientists launched an unmanned balloon into the stratosphere to search for high-energy cosmic rays, followed in 2004 by the balloon-borne Cosmic Ray Energetics And Mass (CREAM) collaborative experiment.

This isn't the first time BLAST has taken to the skies, either. Last year's launch out of Sweden was plagued by a broken mirror, quashing any hope of collecting extra-galactic data, although it did glean information but shiny celestial objects closer to home. The project's scientists hope to rectify that with this most recent flight.

BLAST's balloon is made out of ultra-thin polyethylene film, just like the plastic bags you get from the grocery store, just a little bit more durable, considering the balloon must withstand high-altitude conditions, not just groceries. Those conditions include something called "the polar vortex," apparently a type of atmospheric cyclone. The BLAST experiment ingeniously exploited that vortex, using it to carry its payload around the Antarctic continent before depositing back onto the Ross Ice Shelf, from where it was launched.

Equally impressive is the cutting-edge instrumentation. The "submillimeter" part of BLAST's acronym is  key, since it's the submillimeter wavelengths of radiation that will give us a bitter picture of distant galaxies, in part because it gets past the gas clouds that accompany star formation, which usually obscure regular optical observations. Even the plucky Hubble Space Telescope struggles with that. Plus, when a star forms, there's rather a lot of energy emitted in the submillimeter band, which means that much more data for scientists to analyze. But it's a bit tricky to detect radiation at that scale.

BLAST's reflective telescope uses an aluminum mirror, and it works like any other such telescope: light enters the front of the telescope and reflects off the primary mirror to a secondary mirror, which in turn directs the incoming photons into a receiver. However, BLAST must be pointed away from the sun and through the odd clear patches of the Milky Way galaxy. A "direct hit" of the sun's rays at those altitudes would literally fry the delicate instrumentation onboard. (On the upside, BLAST uses solar panels in the back to power itself.)

The receiver uses filters to divide the photons into three different wavelengths before they pass onto a detector array of highly sensitive heat sensors. "Heat," in this instance, is a somewhat relative term. The photons of interest to BLAST scientists are on the order of 30 degrees Kelvin. (The Antarctic Sun article compares this detection task to "sweeping your hand across a day-old campfire and trying to find a warm ember.)

So, we're talking about very low-energy light, and therefore the need for an even colder detector environment if the instruments have any hope of picking up those critical submillimeter signals. That's where the elaborate cryogenics system comes in. BLAST has its own self-contained refrigeration system capable of hitting lows your standard kitchen fridge can only dream about. Liquid nitrogen takes the first shift, chilling the instruments to 77 degrees Kelvin. Then liquid helium drops the temperature to 4 degrees Kelvin. By continuously pumping in more liquid helium, eventually the temperature cools to about three-tenths of a degree above Absolute Zero (0 degrees Kelvin). The end result of all this technological trickery should be reconstructed images on a par with what you'd get using Hubble, just at a lower resolution.

Even the futuristic notion of a space elevator might get a boost from balloons. (Guest blogger Lee Kottner covered that topic in depth here and here.) In September, LiftPort Group, based in Bremerton, Washington, conducted a 60-day field test of a cable held aloft by four helium balloons, considered a starting point for developing a space elevator. Apparently there were some issues with insects and bats, and we probably won't be seeing a space elevator any time soon, but the balloon-borne tether system could be used to secure WiFi platforms in rural areas, ensuring that every American can indulge their god-given right to check their Blackberries in the middle of nowhere. Balloons -- they're not just for 18th century French papermakers anymore.

Comments

[Chris Clarke]

Wait.

You're stressed out in part because you have too much bubble wrap?

Isn't that a self-correcting condition?

[Jennifer Ouellette]

OMG! I never thought of that... Merry bubble popping relieves stress! :)

[Brian]

Moving? I sympathize. Relocating from Texas to Wisconsin a few years ago was the most stressful thing my wife and I have ever done together.

the balloon-borne tether system could be used to secure WiFi platforms in rural areas,

More than WiFi but that gets the press right now. Other uses could include cameras, radio relay for military or civil disaster purposes.

But how cool that we're still on your mind. Thanks!

[Kristin]

I like how ballooning captured the French imagination enough that they celebrated it on handpainted plates, such as these I saw at the branch of the Air and Space Museum out near Dulles Airport: http://www.radioactive-banana.com/blog/2006/01/24/best-way-to-kill-time-at-the-airport/

I also once went through a book of old French toile fabric prints that they have at the San Francisco Public Library and found a charming pattern with two or three repeating scenes of ballooning. One of the scenes showed some peasants ogling and pointing their rifles at this strange contraption that had come out of the sky. I suppose nowadays the equivalent scene would go onto a t-shirt, not someone's tablecloth or dress...

[Brett]

"It was probably just a matter of time before NASA realized the scientific potential of balloons as a cost-effective means of exploring space, including other planets."

Actually, NASA used balloons in space (quite literally!) as early as 1960 -- Echo 1A and Echo 2. Essentially for bouncing radio and TV signals off of; they were also very bright and seen by huge numbers of people. See: http://en.wikipedia.org/wiki/Echo_satellite

[Alan]

I like your column when I have enough time to read it - found it through Phil Plait. Isn't the internet cool ?
"The number of atoms inside the balloon doesn't change when it's heated (or cooled, for that matter)."
In a sealed weather balloon this is true, but you were talking about a Montgolfier balloon. If temperature changes, volume doesn't much, and pressure has to reach a steady state with the atmosphere, then the number of atoms must be changing.
By the way the number of molecules in the "I Love You" balloon seems to have changed since I bought it for my wife on our anniversary 3 weeks ago. The string is still holding it up, but it must be getting heavier because it's not as high !
Does that confuse things ?

[Louise]

The ANITA balloon-borne experiment was launched from Antarctica December 15, providing a low-cost way to observe cosmic rays.

[Stephen]

The trouble with sealed balloons is that they aren't very well sealed. Atoms in your typical valentine's day balloon migrate out, and others from the air migrate in. Since the helium is lower density than air, any exchange will lead to the balloon getting heavier.

You typically don't get very pure helium, either.

When i was younger, i created hydrogen by electrolisis from water. The oxygen was released and not used. I used a fish tank air pump to put it into a balloon. It zipped up to the ceiling. After a few days, it deflated and dropped to the floor. But it didn't deflate all the way. If it were pure hydrogen in there, it wouldn't have fallen at all. This was proven by filling another balloon only that much.

The next experiment was to ignite a hydrogen filled balloon. A candle was used to burst the balloon and ignite it at the same time. The balloon was brought to it tied to a stick. It had a kind of odd pop sound, but wasn't at all dangerous.

[rootless]

THE FABLE OF THE PROFESSOR WHO WANTED TO BE ALONE

Now it happens that in America a man who goes up hanging to a Balloon is a Professor.
One day a Professor, preparing to make a Grand Ascension, was sorely pestered by Spectators of the Yellow-Hammer Variety, who fell over the Stay-Ropes or crowded up close to the Balloon to ask Fool Questions. They wanted to know how fur up he Calkilated to go and was he Afeerd and how often had he did it. The Professor answered them in the Surly Manner peculiar to Showmen accustomed to meet a Web-Foot Population. On the Q.T. the Professor had Troubles of his own. He was expected to drop in at a Bank on the following Day and take up a Note for 100 Plunks. The Ascension meant 50 to him, but how to Corral the other 50? That was the Hard One.
This question was in his Mind as he took hold of the Trapeze Bar and signaled the Farm Hands to let go. As he trailed Skyward beneath the buoyant silken Bag he hung by his knees and waved a glad Adieu to the Mob of Inquisitive Yeomen. A Sense of Relief came to him as he saw the Crowd sink away in the Distance.
Hanging by one Toe, and with his right Palm pressed to his Eyes, he said: "Now that I am Alone, let me Think, let me Think."
There in the Vast Silence He Thought.
Presently he gave a sigh of Relief.
"I will go to my Wife's Brother and make a Quick Touch," he said. "If he refuses to Unbelt I will threaten to tell his wife of the bracelet he bought in Louisville."
Having reached this Happy Conclusion, he loosened the Parachute and quickly descended to the Earth.

MORAL: Avoid Crowds.

--George Ade, Fables in Slang (1899)