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 September 21, 2001: 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 travelers.
Above: 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!
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 Mesopotamians 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 Center at the University of Colorado at Boulder.
NASA's Space Product Development (SPD)
program encourages the commercialization of space by industry
through 17 such CSCs.
 Left: Probably the oldest carbonated
beverage still consumed today, beer has a long and rich tradition.
[more
information]
Kirsten Sterrett, recently 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 makings 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.
 Below: 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. [more
information]
The behavior 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.
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.
 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.
Above: Yeast are tiny single-celled fungi important
for brewing beer and baking bread. Understanding the puzzling
behavior of such cells in space will benefit pharmaceutical research
here on Earth.
"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.
Below: "Sitting down to dinner" as these astronauts
are doing on the International Space Station can mean floating
above the table while snacking on unfamiliar foods. Small pleasures
like a soda or a beer might be a welcome taste of the ordinary
for out-of-this-world diners.
 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.
Above:
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 the tape stuck to the top-right corner
of the dispenser that reads "50¢" -- astronaut
humor. Image courtesy BioServe.
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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