Perfumes - Space Scents

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, or sperm, around. Although we tend to think of floral smells as sweet and appealing, flowers produce a variety of odours, 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 odours, like that of skunk cabbage.

But whatever they smell like, the odours 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^TM, which is a 17 by 9 by 21 inch enclosure.

"Ninety-nine percent of miniature roses have no odour," said Mookherjee, but Overnight Scentsation is an exception. It emits a fragrance, which Mookherjee described as "a very green, fresh rosy note."