“That which we call a rose, by any other name would smell as sweet.”
Shakespeare knew a few things about romance… and roses. But
here’s something he never considered: roses in space. Would they
smell as sweet in Earth orbit? It’s not as silly as it sounds–at
least perfume industry giant International Flavors & Fragrances (IFF)
didn’t think so. New fragrances are much sought after in the
competitive perfume industry. Some years ago IFF researchers began
to wonder: Could space-traveling flowers yield something new and
exotic? The answer might prove profitable, they figured. And so
began perhaps the most romantic space experiment ever done.
In 1998, IFF teamed with the Wisconsin Center for Space Automation
and Robotics (WCSAR), a NASA Commercial Space Center (CSC) at the
University of Wisconsin. WCSAR’s job is to help companies research
new products in space. NASA’s Space Product Development program at
the Marshall Space Flight Center supports 15 such CSC’s around the
country.
WCSAR researchers had developed a plant growth chamber called
ASTROCULTURE? for the middeck of the space shuttle. It provides
plants with the appropriate temperature, humidity, light, and
nutrients during spaceflight, explains Dr. Weijia Zhou, WCSAR
director. ASTROCULTURE? was perfect for IFF’s purpose, and so on
October 28, 1998, a tiny rose selected by IFF was able to leave Earth
for a 10-day flight onboard the shuttle Discovery (STS-95).
IFF researchers quickly learned that what we call a rose does indeed
smell sweet in space, but it does not smell the same.
Fragrance, in flowers, is a variable and elusive commodity, evolved
solely to help plants reproduce by attracting the insects and animals
they need to spread their pollen [and thus, their sperm] around.
Although we tend to think of floral smells as sweet and appealing,
flowers produce a variety of odors, depending on the preferences of
their pollinators. If bees are lured by the same kinds of smells
that we like, carrion flies, for example, may be drawn by ranker
odors, like that of skunk cabbage.
But whatever they smell like, the odors themselves come from
“volatile oils,” also known as essential oils, because they carry the
essential fragrance of the plant. These highly concentrated plant
extracts all share certain traits; for example, they readily bind to
receptors in olfactory neurons. They also tend to be soluble in
alcohol, but not water, and they often feel oily. Most important is
that they evaporate at room temperature. Indeed, the fragrances used
in perfumes are classified on a scale from 1 to 100, according to how
readily they dissipate.
A plant’s production of volatile oils is strongly affected by its
environment, explained Dr. Braja Mookherjee, who, until his recent
death, was Director of Global Natural Products at IFF. Some plants,
for example, produce more oils at night when their pollinator is
active, and some produce more in the daytime. Temperature, humidity,
and the age of the flower are influential, too. It’s no wonder, said
Mookherjee, that low-gravity should affect a flower’s smell just as
other environmental factors do.
The flower that flew on STS-95 was a miniature rose called “Overnight
Scentsation”–a plant no more than seven inches high, with two buds
just ready to open. The rose needed to be small to fit inside
ASTROCULTURE?, which is a 17 by 9 by 21 inch enclosure.
“Ninety-nine percent of miniature roses have no odor,” said
Mookherjee, but Overnight Scentsation is an exception. It emits a
fragrance, which Mookherjee described as “a very green, fresh rosy
note.”
In low gravity, said Mookherjee, the rose actually produced fewer
volatiles than it did on Earth. But the fragrance that it did
generate was critically altered. The flower in space had a more
“floral rose aroma,” which is aesthetically pleasing.
And, no, the astronauts didn’t just sniff the flower. To collect the
scent, they reached into the ASTROCULTURE? chamber and touched the
rose using a tiny silicon fiber. Less than one centimeter long, and
only 1 to 2 millimeters in diameter, the fiber was coated with a
special liquid to which molecules around the flower petal adhere.
After the shuttle returned to Earth, IFF researchers took the fiber
and analyzed the molecules they found on it.
“We identify the constituents, we know the quantity, and then we can
synthesize [the fragrance] here in the lab,” explained Mookherjee.
The fragrance of a rose is made up of nearly 200 different compounds,
he added.
The rose was sampled four times throughout the STS-95 shuttle
mission. Each time, says Mookherjee, they got a different result.
The scent that they finally arrived at was the average of those
samplings, and the new fragrance has since been incorporated into
“Zen”, a perfume produced by the Japanese company Shiseido.
The collaboration between IFF and WCSAR will continue on STS-107, a
shuttle mission slated for launch in January 2003. This time the
plan is to send up two different plants–a rose and an Asian rice
flower–again placed in the ASTROCULTURE? facility. Like Romeo and
Juliet, the flowers will touch each other. This as well as the low
gravity, said Mookherjee, will alter the molecules they emit.
The ability to do research in space, concluded Mookherjee, gives a
whole new dimension to the field of fragrance studies. “It’s a
fantastic opportunity,” he said… one that the Bard himself might
have appreciated.
Additional information on this article is available at
http://science.nasa.gov/headlines/y2002/18dec_scents.htm?list52260.