Scientists are embarking on a fascinating journey to dissect the smells of space, ranging from the nearest celestial bodies to distant planets hundreds of light-years away. This exploration aims to unveil the complex make-up of the Universe. According to Marina Barcenilla, a space scientist and fragrance designer, our solar system's largest planet, Jupiter, resembles a "stink bomb." Barcenilla explains that Jupiter comprises several layers of clouds, each with distinct chemical compositions, creating an olfactory experience that would be anything but pleasant.
At the top layer of Jupiter’s clouds, scientists believe there are ammonia ice particles, which Barcenilla likens to the stench of cat urine. As one descends into the planet's atmosphere, the smell worsens, with the presence of ammonium sulphide, a combination notorious for its resemblance to rotting eggs. Delving deeper, one encounters Jupiter's thick bands of color, likely formed by plumes of ammonia and phosphorus, adding a note of petroleum oiliness mixed with a hint of garlic to the mix.
Barcenilla, a PhD student in astrobiology at the University of Westminster in London, has been busy recreating the scents of outer space for an exhibition at London's Natural History Museum titled "Space: Could Life Exist Beyond Earth?" This project has revealed that the cosmos is surprisingly aromatic, with scents ranging from the sweet aroma of almonds to the pungent odor of rotten eggs. Each celestial body—comets, planets, and gas clouds—possesses its own unique scent profile.
Before venturing into the aromatic wonders of space, it’s essential to understand the nature of smell itself. Despite being often overlooked, the sense of smell is one of our most ancient senses. Even single-celled organisms, such as bacteria, rely on chemical cues to navigate their environments, demonstrating that the ability to detect smells has been crucial for survival since the dawn of life.
In humans, the sense of smell is intricately linked to our emotional well-being and plays a significant role in social interactions. The dense nerve clusters in our noses, which consist of millions of specialized neurons, enable us to identify various chemicals in our environment. This ability aids in recognizing food, avoiding dangers, and triggering memories.
For astronauts, the experience of smell can be both comforting and disorienting. Helen Sharman, the UK's first astronaut, recalls her time on the Mir space station in 1991, where she was given a sprig of wormwood to take with her. She would crush the leaves to release their sage-like scent, a reminder of Earth during her eight-day mission. However, in the microgravity environment of space, the perception of smell can be quite different. Sharman notes that hot air does not rise, making it difficult to detect smells from hot food unless one gets close to the source.
Astronauts have reported various unusual odors in space, including a smell reminiscent of charred meat, gunpowder, or burnt electrical wiring—a phenomenon still shrouded in mystery. Sharman theorizes that this metallic smell could be caused by oxidization. In the near-vacuum of space, atomic oxygen can cling to astronauts’ suits and tools, creating ozone when it reacts with the oxygen in the space station.
In recent years, the exploration of space has taken on new dimensions with advanced technology. For instance, NASA's James Webb Space Telescope (JWST) made headlines in 2022 by detecting carbon dioxide (CO2) in the atmosphere of an exoplanet, WASP-39 b. Although the telescope does not "smell" in the traditional sense, it can identify various chemicals by analyzing how starlight interacts with a planet's atmosphere.
Space is vast and filled with worlds that present a plethora of unique scents. Chemical analyses suggest that Titan, Saturn's largest moon, could smell like sweet almonds, while the distant planet HD 189733 b might have an odor akin to rotten eggs. Furthermore, interstellar dust clouds in the Milky Way may emit scents reminiscent of ice cream and ammonia.
As scientists investigate cosmic aromas, they also seek to uncover clues about the potential for life beyond Earth. Recently, a team of researchers, including astrophysicist Subhajit Sarkar, detected what could be the scent of life on the exoplanet K2-18b. This planet, located approximately 120 light-years away, may contain dimethyl sulphide (DMS), a compound often associated with marine life on Earth. The findings suggest that K2-18b could harbor an ocean teeming with life, although further investigation is necessary to confirm this hypothesis.
Interestingly, many of the scents associated with space are not entirely alien to us; they can be found on Earth as well. Barcenilla has attempted to recreate the scent of space, and her Mars scent pod at the Natural History Museum evokes memories of rust and dampness, reminiscent of childhood experiences. In contrast, Sharman fondly recalls returning to Earth in 1991, where the fresh air upon opening the hatch of her spacecraft was a heavenly delight.
While the exploration of the cosmos continues, it is essential to appreciate the unique scents that our own planet offers. As Sharman aptly states, "There is nothing like the scent of our own planet." The aromas of Earth, combined with the intriguing scents of space, provide a sensory experience that enriches our understanding of both our home and the vast Universe beyond.
