The smell of rain: how our scientists invented a new word

Rain: you can tell when rain is coming just by the smell. Flickr/Ulf Bodin, CC BY-NC-SA

Rain: you can tell when it’s coming just by the smell. Flickr/Ulf Bodin, CC BY-NC-SA

By Howard Poynton, CSIRO

Australia’s CSIRO has come up with some pretty amazing inventions over the past 86 years of research, from polymer banknotes to insect repellent and the world-changing Wi-Fi. But we can also lay claim to something a little more esoteric – we actually invented a whole new word.

And no, we’re not talking about one of these new-fangled internet words like “YOLO”, “selfie” or “totes”.

The word is “petrichor”, and it’s used to describe the distinct scent of rain in the air. Or, to be more precise, it’s the name of an oil that’s released from the earth into the air before rain begins to fall.

This heady smell of oncoming wet weather is something most Australians would be familiar with – in fact, some scientists now suggest that humans inherited an affection for the smell from ancestors who relied on rainy weather for their survival.

Origins

Even the word itself has ancient origins. It’s derived from the Greek “petra” (stone) and “ichor” which, in Greek mythology, is the ethereal blood of the gods.

But the story behind its scientific discovery is a lesser known tale. So, how is it that we came to find this heavenly blood in the stone?

Nature of Argillaceous Odour might be a mouthful, but this was the name of the paper published in the Nature journal of March 7, 1964, by CSIRO scientists Isabel (Joy) Bear and Richard Thomas, that first described petrichor.

Thomas had for years been trying to identify the cause for what was a long-known and widespread phenomena. As the paper opened:

That many natural dry clays and soils evolve a peculiar and characteristic odour when breathed on, or moistened with water, is recognised by all the earlier text books of mineralogy.

rain 2

Was it something in the soil that gave rise to the smell? Flickr/Georgie Sharp, CC BY-NC

The odour was particularly prevalent in arid regions and was widely recognised and associated with the first rains after a period of drought. The paper went on to say:

There is some evidence that drought-stricken cattle respond in a restless matter to this “smell of rain”.

The smell had actually been described already by a small perfumery industry operating out of India, which had successfully captured and absorbed the scent in sandalwood oil. They called it “matti ka attar” or “earth perfume”. But its source was still unknown to science.

Joy and Richard, working at what was then our Division of Mineral Chemistry in Melbourne, were determined to identify and describe its origin.

By steam distilling rocks that had been exposed to warm, dry conditions in the open, they discovered a yellowish oil – trapped in rocks and soil but released by moisture – that was responsible for the smell.

The diverse nature of the host materials has led us to propose the name “petrichor” for this apparently unique odour which can be regarded as an “ichor” or “tenuous essence” derived from rock or stone.

The oil itself was thus named petrichor — the blood of the stone.

Bring on the humidity

The smell itself comes about when increased humidity – a pre-cursor to rain – fills the pores of stones (rocks, soil, etc) with tiny amounts of water.

While it’s only a minuscule amount, it is enough to flush the oil from the stone and release petrichor into the air. This is further accelerated when actual rain arrives and makes contact with the earth, spreading the scent into the wind.

According to the Nature Paper:

In general, materials in which silica or various metallic silicates predominated were outstanding in their capacity to yield the odour. It was also noted that the odour could be obtained from freshly ignited materials rich in iron oxide, with or without silica.

It’s a beautiful sequence of events, but one that may be hard to visualise.

Thankfully, in a testament to the ongoing scientific fascination with this finding, a team of scientists at the Massachusetts Institute of Technology have just this year released a super slow motion video of the petrichor process in motion.

Using high-speed cameras, the researchers observed that when a raindrop hits a porous surface, it traps tiny air bubbles at the point of contact. As in a glass of champagne, the bubbles then shoot upward, ultimately bursting from the drop in a fizz of aerosols.

The team was also able to predict the amount of aerosols released, based on the velocity of the raindrop and the permeability of the contact surface which may explain how certain soil-based diseases spread.

Lasting legacy

There’s a small body of research and literature on petrichor that’s fascinating in its own right, including Thomas and Bear’s subsequent paper Petrichor and Plant Growth a year after they first named the smell.

So what happened to Joy Bear and Richard Thomas?

Richard Thomas with Joy Bear, studying petrichor (date unknown).

Richard Thomas with Joy Bear, studying petrichor (date unknown).

Richard had actually retired from CSIRO in 1961 when he was First Chief of the Division of Minerals Chemistry. He died in 1974, aged 73.

Joy, aged 88, a true innovator and pioneer in her field, retired from CSIRO only in January this year, after a career spanning more than 70 years.

The joint discovery of petrichor was just part of a truly remarkable and inspiring career which culminated in 1986, with Joy’s appointment as a Member of the Order of Australia for services to science.

We are thankful to both for the lasting legacy on giving a name to the smell of rain and to Joy for the role model she has been to so many women in science.


This is part of a series on CSIRO Inventions.

This article was originally published on The Conversation.

Read the original article.


Discovering the enigma moth: a golden-winged relic from a long-past age

A female adult 'enigma' moth on a Southern Cypress-pine stem. Image: George Gibbs

A female adult ‘enigma’ moth on a Southern Cypress-pine stem. Note the beautiful colouring of its wings. Image: George Gibbs

A living dinosaur. A missing evolutionary link. A specimen unlike any seen before it.

With such weighty words being thrown around, you could be forgiven for thinking we had discovered a Yowie, a Loch Ness Monster, or another Jurassic Park script.  But the truth, while being a little more unassuming, is no less the stuff of legends.

In actual fact, we’ve found an enigma.

Today, we unveiled the Aenigmatinea glatzella – which has been coined the ‘enigma moth’ – to the world. This tiny insect, which has so far only been found in an isolated pocket of Kangaroo Island, South Australia, represents not just an entire new species of moth, but an entire new family. It’s the Lepidoptera equivalent of discovering, say, the platypus.

This is the first time since the 1970s that a new family of primitive moths has been identified anywhere in the world. So for a bald bug that lives, mates and dies in one day and could fit on a five cent piece, the enigma moth is causing quite a stir.

A dorsal illustration of the moth.

An illustration of the dorsal side of the moth.

You can read more about the moth and our role in its discovery – as well as the launch of a foundation to support research into Australian moths and butterflies, and the moths and butterflies in our Australian National Insect Collection in Canberra – here. But in the meantime, we present to you the top five facts about this flying enigma:

    1. It is helping us crack evolution’s code. DNA analysis indicates that the evolution of moths and butterflies is even more complex than previously thought. For example, while the discovery of this new moth strengthens the evolutionary relationships between other primitive moth families, it also suggests that tongues evolved in moths and butterflies more than once.
    2. The species name glatzella has an amusing double meaning. While bestowed in honour of its discoverer, Dr Richard Glatz, in German glatze means ‘bald head’. Indeed, this cryptic moth is bald – it hardly has any scales on its head. But elsewhere on the body, these scales appear as a brilliant purple and gold.
    3. It’s rare. It has so far only been found at one location on Kangaroo Island off the coast of South Australia.
    4. It lives on Southern Cypress-pine trees (Callitris gracilis), a very ancient element of our flora dating back to the supercontinent Gondwana.
    5. The adult moths are short-lived. In just one day they emerge from their cocoons, mate, females lay their eggs, and then die.

And, in case you haven’t seen it already, we’ve created this excellent short film of the enigma moth to honour its official introduction to the public. Enjoy!


A new antenna for old friends: celebrating 55 years of AUS-US space communication

NEW VISTAS: Deep Space Station 35 will operate for many decades. We can only begin to imagine what future discoveries it might make. Credit: Adam McGrath

NEW VISTAS: Deep Space Station 35 will operate for many decades. We can only begin to imagine what future discoveries it might make. Credit: Adam McGrath

It’s been a momentous couple of days in the history of Australian space exploration. Just yesterday, the newest antenna in NASA’s Deep Space Network was officially commissioned at our Canberra Deep Space Communication Complex, five years to the day from its original ground breaking ceremony.

DAY OR NIGHT: Deep Space Station 35 will be operating 24/7 to help make discoveries in deep space.

DAY OR NIGHT: Deep Space Station 35 will be operating 24/7 to help make discoveries in deep space.

The new dish, Deep Space Station 35, incorporates the latest in Beam Waveguide technology: increasing its sensitivity and capacity for tracking, commanding and receiving data from spacecraft located billions of kilometres away across the Solar System.

The Canberra Complex is one of three Deep Space Network stations capable of providing two-way radio contact with robotic deep space missions. The Complex’s sister stations are located in California and Spain. Together, the three stations provide around-the-clock contact with over 35 spacecraft exploring the solar system and beyond. You may remember this technology being utilised recently for the Rosetta and Philae comet landing; and for communicating with the ever so far-flung New Horizons spacecraft on its journey past Pluto.

"Does it get Channel two?"

“Does it get Channel Two?”

As a vital communication station for these types of missions, the new antenna will make deep space communication for spacecraft and their Earth-bound support staff even easier.

But don’t put away the space candles just yet. For today marks the 55 anniversary of the signing of the original space communication and tracking agreement signed between Australia and the United States, way back on the 26th February 1960.

It is a partnership that has that has led to many historic firsts and breakthrough discoveries – the first flybys of Mercury and Venus, the vital communication link and television coverage of the first Moonwalk, robotic rover landings on (and amazing views from) the surface of Mars, the first ‘close-ups’ of the giant outer planets and first-time encounters with worlds such as Pluto.

The first ever Moon landing: a momentous occasion, broadcast around the world thanks to the Australian-US partnership.

The first ever Moon landing: a momentous occasion, broadcast around the world thanks to the Australian-US partnership.

So, we say welcome to the newest addition to the Deep Space Network and happy birthday to our space-relationship with the US. Here’s to another fifty five years of success!

P.S. We couldn’t finish the blog without including this little gem:

A famous photobomb, taken during the antennae's construction.

A famous photobomb, taken during the antennae’s construction.


Powerful new tool produces proteins in 3D

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The amazing depth of atomic-scale 3D structural information now available via Aquaria.

By Andrew Warren

If you’re a regular at the gym or an early morning boot-camp fanatic, it’s possible that the first thing you picture when you think of protein is the powder you use to make your post-workout recovery shake.

But when our scientists discuss protein, they’re talking about the many thousands of molecules that act as the essential building blocks of life as we know it. Because proteins are so important to constructing life, researchers need a way to visualise the exact ways in which they fit together so that they can better understand the functions they play in our bodies.

With this in mind, a team of international programmers and bioinformaticians (think biology, computer science and maths mixed together) led by our very own Dr Seán O’Donoghue have created a new web-based tool named Aquaria that can create unprecedented 3D representations of protein structures.

Aquaria is based on the Protein Data Bank, an online resource which houses more than 100,000 structures of proteins that contains a wealth of detail about the molecular processes of life. But Sean and his teams were conscious that few biologists were taking full advantage of the site. The Protein Data Bank is designed for and by biologists who are expert in structures; however for most biologists, its organisation can be confusing.

So, they created Aquaria to make this valuable information more accessible and easier to use for discovery purposes.

Freely and publicly accessible, Aquaria can help scientists like ecologists, nutritionists and agriculture, biosecurity and medical researchers to streamline their discovery process and gain new insight into protein structures.

Sean’s team added additional layers of information (like genetic differences) to the basic protein structure and made it accessible in a fast, easy-to-use interface that’s visualised in a fully 3D environment.

“We’ve added protein sequences that don’t yet have a structure, but are similar to something in the Protein Data Bank,” says Sean.

“That meant we first had to find all these similarities. We took over 500,000 protein sequences and compared every one of them with the 100,000 known protein structures, and that has given us around 46 million computer models.

ICAM-1 a

This image shows an example of one of the many spectacular molecular structures that science has determined at atomic resolution. This is the Aquaria view of Intercellular Adhesion Molecule 1, a protein that occurs on the surface of endothelial and immune system cells.

“For example, you can add Single Nucleotide Polymorphisms (SNPs) that cause protein changes, then visualise exactly where those changes occur in the protein structure. This provides valuable insight into why proteins sometimes completely change their function as a result of one small change in the DNA code.

“You can then ask interesting questions like ‘Does this set of SNPs cluster in 3D?’ and the answers to such questions can set new research directions.”

Aquaria was developed in collaboration with Dr Andrea Schafferhans from the Technical University of Munich, and is hosted with support of a grant from Amazon Web Services.

To learn more about Aquaria, you can take part in a special webinar scheduled for 9am Tuesday, 3 February (AEDST).


Viva Parkes-Vegas!

Viva Parkes-Vegas!

When stars collide: Elvis meets The Dish

By Glen Nagle

The town of Parkes, NSW – home of our famous Parkes Radio Telescope – has slipped on its Blue Suede Shoes.

In the second week of January each year, Parkes marks the birthday of Elvis Presley with a massive festival celebrating everything Elvis. It started over 20 years ago as a one-day get together of just a few hundred fans. In 2015, the festival has grown to cover a week of events, shows, parades and exhibits and over 15,000 visitors more than doubling the town’s population.

Along with one of the largest collections of Elvis memorabilia on permanent display at the Henry Parkes Visitor Centre (donated by Wiggles performer, Greg Page), the Parkes Elvis Festival is one of the town’s major icons.

The other great icon of course is the Dish – our very own Parkes radio telescope – so combining these two great icons into one stellar event was always going to be, quite literally, a match made in Heaven.

'Return to sender' took on a new meaning for the Dish last night.

‘Return to sender’ took on a new meaning for the Dish last night.

On Wednesday, 7th January an inaugural concert was held at the Dish to help mark the opening night of the Festival – and to celebrate what would have been the King’s 80th birthday the following day.

Starring popular Elvis tribute artist, Shakin’ Rick Mackaway, and backed by the fabulous rock band, The Wilsonics, the dinner and show night attracted hundreds of people from across the region and as far and wide as Canberra, Wollongong, Sydney, Adelaide and Melbourne.

Storm clouds threatened earlier in the day, but nothing was going to rain on this parade of love for the King and the Dish. The clouds almost magically bypassed the telescope and the brightest stars in heaven came out for an incredible night of songs, dancing and laughter against the impressive backdrop of Australia’s iconic radio telescope.

Shakin' Rick, rockin' in to the night.

Shakin’ Rick, rockin’ in to the night.

Continuing to observe the heavens throughout the show, the Dish even performed during the intermission with several large moves enthralling the audience and provoking  questions about both the science behind, and the history of, the Dish.

As the evening came to a close with a final encore performance and the audience departed, the number one question was, “Are you going to do it again next year?!”

Hmmm? Elvis and the Dish 2! Two icons, exciting audiences everywhere with music and astronomy.

The possibilities are endless. Watch this space.


Waking Up to New Horizons

Nicholas Kachel:

Our Canberra Deep Space Communication Complex just received a signal, sent at the speed of light, from 4.8 billion kilometres away. Who was it from? What was it about? Find out below…

Originally posted on Universe @ CSIRO:

New Horizons' flies past Pluto in this artists' rendition. Image: NASA/JHUAPL New Horizons’ flies past Pluto in this artists’ rendition. Image: NASA/JHUAPL

I guess we all love to sleep in on a Sunday morning, maybe just snoozing under the doona, laying there for a few hours before getting up for a late brunch. Ah! Luxury.

On Sunday 7th December 2014, the New Horizons spacecraft, 5 billion kilometres away from the warmth of Earth, had little time to sleep in. It was ‘wake up’ day. The final awakening from hibernation for the next 2 years until well after its encounter with rapidly approaching dwarf planet, Pluto, set for the 14th July 2015.

Waiting back on Earth to hear the spacecraft’s morning ‘alarm’ go off was the giant 70 metre antenna dish at the CSIRO-managed, Canberra Deep Space Communication Complex – Deep Space Station 43 (DSS43).

Deep Space Station 43 in Canberra receiving the 'wake up' call from the New Horizons spacecraft. Image: CDSCC/CSIRO Deep Space Station 43 in Canberra receiving the ‘wake up’ call from the New…

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World Soil Day: a chance to worship the ground we walk on

By Leon Braun

It’s downtrodden, underfoot and often under appreciated, yet so crucial to our existence that one of our scientists describes it as “the complex natural medium that supports all life on Earth”. It holds our crops, stores and purifies our water, and provides habitat for amazing creatures like the giant Gippsland earthworm, which can reach up to 3 m in length. But most of us only think about it when we’re trying to get it out of footy socks on laundry day.

It’s soil – and today (and all next year) it gets a bit of long-overdue recognition. December 5 is World Soil Day, and the United Nations has declared 2015 to be International Year of Soils. That’s a good thing, because globally, soils are under threat: from erosion, poor land management and urbanisation. At the same time, we need soils more than ever to produce the food we need for a growing population, to help manage climate change and to ensure ecosystem health.

Cracked soil at Chowilla, South Australia.

Cracked soil at Chowilla, South Australia.

Luckily for Australia’s soils, they have CSIRO looking out for them. We started researching soils in 1929, published the first soil map of Australia in 1944, and have been working hard ever since to improve our understanding and management of soils. We’re looking at ways to make agricultural soils more productive and to ensure they’re used sustainably, so future generations can continue to reap their bounty. And we’re working internationally too, so it’s not just Australia that benefits.

Our latest achievement (with allies from around the country) is the Soil and Landscape Grid of Australia, a digital map of Australia’s soils with two billion ‘pixels’ of about 90 by 90 metres, down to a depth of two metres below the surface. It contains information such as water holding capacity, nutrients and clay, and has applications for everyone from farmers deciding where to plant their crops to conservationists looking for habitats for endangered native species. You can read more about it here.

We’re also home to the Australian National Soil Archive, which has just gotten a new home in Canberra. The archive contains about 70,000 samples from almost 10,000 sites across Australia, the oldest dating back to 1924. Each sample represents a time capsule of the Australian landscape at the time it was collected, so we can measure things like caesium dispersal from the British nuclear tests at Maralinga and the impact of phosphate-based fertilisers on agricultural land. The archive is a vital national asset for soil researchers and industry, and has even been used by the Australian Federal Police to examine the potential of new forensic methods. Finally, data from the archive powers our first official app, SoilMapp, which puts information about Australian soils at your fingertips. This is incredibly useful, whether you’re growing canola on a farm in Western Australia or planning a major roads project in Victoria.

So as you go through your day today, eat your lunch, wipe your shoes, just remember: it takes 2000 years to form 10 centimetres of fertile soil suitable for growing our food, but just moments for that soil to blow away or get covered in a layer of asphalt. Something to think about next time you sit down to a meal – or do your laundry.


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