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Beer in Space

Bubbly, frothing and ticklish - soft drinks and beer promise a welcome taste of home to faraway space travellers.

by Patrick L. Barry

People can endure many discomforts in exchange for the thrill of living in space. The nausea of space sickness, fitful sleep without the familiar pressure of a bed, tasteless meals eaten from plastic bags - it's all fine as long as the novelty of being in space lasts.

But after a while, the blush of excitement inevitably fades, and astronauts will begin to long for the comforts of home. For example, the nose-tickling bubbles of a refreshing soft drink or a frothy beer after work - these simple pleasures that we take for granted on Earth could do wonders for morale among long-term space travellers.

Of all the carbonated beverages people enjoy drinking today, beer is the oldest and most familiar. Beer has likely been a part of society since human civilization first arose. Historians believe that the ancient Mesopotamian's and Sumerians were brewing beer as early as 10,000 BC. The ancient Egyptians and Chinese brewed beer, as did pre-Columbian civilizations in the Americas.

For the tradition of beer and its fizzy cousins to continue as people begin settling space, a few questions must first be answered.

Will fermentation work the same in weightlessness? What happens to carbonation when there's no buoyancy to bring the bubbles to the top? Can space beer form a proper head? Scientists who study the physics of gas-liquid mixtures would love to know!

Two separate space shuttle experiments tackled these questions. Both were engineered and mediated by BioServe Space Technologies, a NASA-sponsored Commercial Space Centre at the University of Colorado at Boulder. NASA's Space Product Development (SPD) program encourages the commercialisation of space by industry through 17 such CSCs.

A fizzy Coca-Cola droplet floats aboard the Space Shuttle in August 1985. In a weightless environment, bubbles of carbon dioxide ("carbonation") aren't buoyant, so they remain randomly distributed in the fluid. The result can be a foamy mess!

Kirsten Sterrett, a University of Colorado graduate student, first became interested in how beer would brew in space while working at the Coors Brewing Company. Having studied aerospace engineering as an undergraduate, she began to wonder: How would yeast that perform fermentation fare in orbital free fall? The answer would not only shed light on the possible making of space-beer, but also provide valuable information to pharmaceutical companies with a keen interest in the biology of orbiting microbes.

When she returned to CU-Boulder for her master's work, she chose the topic for her thesis. Her experiments were sponsored by Coors and flown on the shuttle with the help of BioServe.

"I always said I wouldn't do an experiment that I couldn't eat or drink in the end," she jokes.

"Actually, after the experiment was all done, I gave (the space-beer) a little taste." The sample was only about 1 ml, which wasn't really enough to savor, she says, "but why throw something like that away?"

Along with her taste test, Sterrett performed a protein analysis on the beer and the yeast, measured the beer's specific gravity (the force exerted on it by gravity per unit volume), and "repitched" the yeast by brewing subsequent batches of beer with it. By all of these measures, the space-beer appeared to be essentially the same as beer brewed on Earth.

The behaviour of the yeast was somewhat puzzling, though. The total cell count in space-borne samples was lower that of "control" samples brewed on the ground, and the percentage of live cells was also lower. One of the yeast's proteins also existed in greater amounts in the space-brew.

Probably the oldest carbonated beverage still consumed today, beer has a long and rich tradition.

Sterrett's experiment couldn't suggest reasons for these changes, but the overly abundant protein bears some resemblance to a general stress protein.

The low cell count was particularly surprising, says Sterrett. In space, yeast cells remain evenly dispersed within the "wort" - a brewers' term for the pre-fermentation mixture of water, barley, hops, and yeast. Ideally, this would give the yeast cells better access to nutrients in the wort compared to similar mixtures on Earth, where the weight of the cells causes them to pile at the bottom one on top of the other.

"It's the same question that we're asking on the pharmaceutical side," says Louis Stodieck, director of BioServe. "We know from subsequent space experiments sponsored by Bristol-Myers Squibb Pharmaceutical Research Institute that the efficiency of producing fermentation products increases [in a weightless environment], in fact quite significantly." Some of those experiments produced as much as three times the fermentation products as control samples on the ground.

A far cry from the copper vats used to brew beer here on Earth, this Fluid Processing Apparatus was used by Sterrett to ferment a tiny batch of space-brew.

Pharmaceutical companies frequently use genetically-engineered microbes - usually bacteria - to produce medicinally-valuable proteins such as antibiotics through fermentation. By introducing the gene that codes for the protein into the bacteria's DNA, scientists convert the microbes into inexpensive, self-replicating medicine micro-factories.

Space research with microbe fermentation might help improve this process.

"What we're trying to do now is to find the specific mechanism of that (increased fermentation efficiency in space), and then we can ask whether we can modify the fermentation process on Earth to take advantage of that - or is it possible that we could genetically engineer an organism to mimic what it does in space," Stodieck says.

A more efficient fermentation process, even by a small percentage, could potentially save millions of dollars in production costs.

For beer, of course, increased fermentation efficiency means a more alcoholic brew - not necessarily good news for crew members who need to remain sober in the dangerous environment of space. The alcohol content of space-brews would need to be adjusted accordingly and, of course, consumed in moderation.

But for alcohol content to even matter, future space residents will first have to get the beer into a drinking container - a trickier feat than it may seem.

"How do you dispense a beverage and keep the carbonation in solution until the person is ready to drink?" Stodieck asks. "That's the challenge."

Changes in temperature and pressure, or even physical agitation of the beverage as it's dispensed, can cause carbonation to come out of solution prematurely. Because bubbles don't rise in free-fall the result can be a foamy mass.

This problem was addressed by experiments flown on the shuttle by The Coca-Cola Company, again with the help of BioServe. "They (The Coca-Cola Company) have a lot of technology that they develop for future ways of providing their drinks anywhere and everywhere," Stodieck notes. And indeed, their dispensing device flown on the shuttle managed to serve a drinkable cola. It controlled the temperature of the beverage during mixing and dispensing with computer accuracy, and minimized agitation.

Image Courtesy Bioserve

By dispensing the drink into a collapsible bag inside the bottle, the pressure around the fluid can be constantly controlled, thus preventing the carbonation from coming out of solution too quickly. The image on the right shows the dispenser being used aboard the space shuttle. (Note there is a tape stuck to the top-right corner of the dispenser that reads "50ยข" - astronaut humour).

Similar technology should prove effective for carbonated space beers. Unfortunately it doesn't lend itself to the traditional frosty glass mug! Instead, beverages are dispensed into a special bottle (pictured above) that screws onto the dispenser. The bottle itself, which contains a collapsible bag, is internally pressurized. The pressure around the bag is slowly released as the beverage enters, maintaining the drink under constant pressure and producing a palatable soda or beer.

So maybe it's not exactly like having a beer on Earth, but astronauts might nevertheless welcome a sip from the strange contraption. Bubbly, frothing, and ticklish - it's a welcome taste of home.


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First Science 2014