Focus On Science
STORIES FROM THE FIELD: MADAGASCAR
Catherine Wheller is completing her PhD in the School of Earth Sciences, with a focus on igneous and metamorphic petrology. Catherine also has a Bachelor of Science and a BSc (Honours) from the University of Melbourne. She visited the enigmatic African island in search of rocks that hold the key to the formation of Gondwana.
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Many researchers are bursting with field stories; tales of arduous travel to far-off places, of courageous food choices, of staring at the stars listening to the sound of the jungle. And, of course, of juggling kilo upon kilo of rocks in their backpacks.
For Catherine Wheller, a final-year PhD student in the School of Earth Sciences at the University of Melbourne, these field stories include ancient rocks, perilous roads and a newborn Malagasy girl named ‘Wheller’.
My PhD research took me to Madagascar with Dr Steven Boger, also from the University of Melbourne, and Professor Richard White from Johannes Gutenberg University Mainz. We were searching for rocks that could hold clues about the formation of the supercontinent Gondwana.
Rocks found in the south of the island record an event that took them to extremely high temperatures around 520 million years ago. By looking at the timing of other events around the world, it is thought that this preserved history in Madagascar represents one of the final collisions involved in the formation of Gondwana.
Under the supervision of Professor Roger Powell, I looked deep into the minerals that make up rocks in order to find out the conditions in which this part of the Earth is formed.
Events such as continents colliding at plate boundaries can cause rocks formed at the surface (sedimentary or igneous) to be buried deep into the crust. The deeper a rock gets buried (or ‘subducted’) the higher pressures and temperatures the rock experiences. Minerals in the rock change to reflect the changing conditions. After the burial has stopped and fluid runs out, the minerals stop changing.
After millions and millions of years, these rocks can be found back at the surface (via erosion and uplift) and record that an extreme event occurred. We can look at the minerals preserved to piece together the Schoothe history of the terrane. The timing of this heating event can then be determined to match up with events elsewhere in the world.
My work is to quantify the pressure and temperatures associated with these rocks, and therefore this final collision.
By investigating how minerals change with the conditions and what can effect these changes, we can use this knowledge to identify terranes all across the world that formed in the same type of event (i.e. as a result of subduction or mountain building) and piece together a global history of the movement of our continents.
I spent one month in Madagascar, flying into the capital, Antananarivo, to organise supplies and collect our field vehicle and guide. It took three days to drive about 400 km down the east coast before heading inland, where the scenery changed suddenly from dodging children and chickens on the roads to apparent isolation.
Typically, days included manoeuvring the Hilux through narrow dirt roads, either overused to the point of collapse or only used by zebu (cattle) carts, from village to village. With a map in hand, we targeted areas of high magnetism – a key feature of the rocks we aimed to sample.
Each night we approached a new village and camped nearby, often fortunate to experience the hospitality of the chief and his family. In most places we were the first foreigners to visit in a generation.
The following is a field account from my diary, recalling my time in the village of Imanombo, a central market town near where our best rock samples were taken.
We are working to a ‘field clock’ – awake at 5:30am and in bed at 8:00pm. The moon is getting fuller now and sleeping in a tent under the moonlight is blinding.
We arrive in Imanombo to find the chief and his family. We are to camp behind his house near the zebu and turkey pen. The turkeys do not seem to like the zebu and gobble in protest, making for a night full of strange sounds.
That evening we share some local music and dance with the children, as I try to keep up with the fast beat. A reciprocal sharing of knowledge leads to Aussie rock being played for what I believe to be the first time in southern Madagascar. I must also take responsibility for introducing the ‘chicken dance’ to the locals of this remote village.
We stay here for two nights, the longest we have stayed in a village. Arriving back at dusk one afternoon, the chief asks whether I want to ride on his motorbike with him (this is obviously his pride and joy; it was wheeled out during the day and polished). We ride out of the village down a straight track with the sun setting over the mountains.
On the last evening, the chief’s nephew proclaims some news – the chief’s wife had just given birth to a daughter, their second. But that isn’t all. The timing of the birth is not a coincidence, but fate; a foreign girl has come into their village, accepted their hospitality, played with their children and brought together two cultures where there is often mistrust, with the motorcycle trip ultimately solidifying the ‘you are one of us’ mentality. Consequently, the chief would like to name his newborn daughter after me.
This is translated to me through a giant grin, which only grew as I am absolutely struck dumb by the honour. This is not a simple process though – as it happens, his eldest daughter’s name is ‘Catharina’ and so ‘Catherine’ wasn’t an option. However, they did like the sound of ‘Wheller’ - here pronounced ‘Whale-a’. Feminine names often stress ‘a’ on the last syllable, so this was perfect! So there you have it – there is a little girl born in remote southern Madagascar called ‘Wheller’.
We could easily have spent many more weeks in the care of the Malagasy. And while there are no more field expeditions in the near future, there are still more research questions to be answered.
Where is the location of the suture that joined the African and Indian parts of the continents? Does this suture extend into then neighbouring, now isolated Sri Lanka, Tanzania and Antarctica? And most importantly, on which Malagasy rock did I leave my camera lens?
FINDING A NEEDLE IN A SPACE HAYSTACK
Stephanie Bernard is completing a PhD in the School of Physics, focusing on cosmology and extragalatic astronomy. Stephanie also has a Bachelor of Science and a Master of Science (Physics) from the University of Melbourne, and she has been given rare access to the Spitzer Space Telescope to explore the origins of the universe.
Stephanie Bernard is one in 24 million.
The University of Melbourne PhD candidate is the only Australian given access to NASA’s Spitzer Space Telescope, and she is using her time to explore one of the earliest galaxies in the universe.
Selected from hundreds of astrophysicists seeking access to the telescope for 12 months (beginning mid-2016), Ms Bernard is now analysing infrared signals from an ancient galaxy that could hold the secrets to how life developed in the universe.
“We’re strongly focused on understanding how the first generation of stars formed,” she says.
Scientists have dated the birth of the universe to about 13.8 billion years ago, when the Big Bang occurred. Ms Bernard and her supervisor, astrophysicist Dr Michele Trenti, from the School of Physics, have just received their first lot of data from Spitzer, and they are focused on a large galaxy – bigger than our own Milky Way – called 11153+0056_514, which formed sometime between 500 and 800 million years after the Big Bang.
“So what we’re doing is going back 13 billion years in time,” Ms Bernard says.
Just the process of finding a galaxy this old is a challenge, let along exploring its intricate details and origins.
“It’s like a needle in a haystack; these galaxies are just a small patch in the sky, something like 150 to 200 times smaller than the moon,” Dr Trenti says.
“We can search thousands of galaxies, and if we’re lucky, there might be one that’s 13 billion years in the past. And if you’re after the brightest galaxies at the time, those are even rarer, because galaxies start forming small and then over time they grow and they often merge into much bigger galaxies.”
Formerly known as the Space Infrared Telescope Facility, the powerful Spitzer Space Telescope is part of the NASA Great Observatories program.
It was later named after astronomer Lyman Spitzer, who in the 1940s advocated the concept of space telescopes.
The telescope was blasted into space in 2003 and NASA planned to operate it for two and a half years, possibly up to five.
Now, in its 13th year, Spitzer is still going strong, despite its original use-by-date having well and truly passed. While some of its original functions no longer work, because the telescope has run out of its liquid helium fuel, its two short wavelength infrared array cameras still operate.
And it is this infrared capability that makes access to Spitzer so important.
To use the telescope, Ms Bernard sends the coordinates of the galaxy to NASA, who then position the telescope to that area when there are enough other requests for data from that particular corner of the universe. Raw data is then emailed to Ms Bernard, who analyses it.
Ms Bernard and Dr Trenti found galaxy 11153+0056_514 using the better-known Hubble Space Telescope, but in order to explore its details further, they needed to see it in infrared, which cannot be seen with the human eye or Hubble.
Dr Trenti says seeing these galaxies in infrared is important because the universe is expanding. As the light from this galaxy travels towards us it loses energy, because space is stretched.
“These distant galaxies would have emitted high-energy UV light, but because the universe has grown approximately 10 times larger in the past 13 billion years, by the time this light reaches us, it has been stretched, and the energy is lower than what the human eye can see,” Dr Trenti says.
Given Spitzer’s age, and the fact the vastly more advanced James Webb Telescope – which will eventually replace both Hubble and Spitzer – is set to be launched in 2018, this was likely the last opportunity for Ms Bernard to use Spitzer.
The images that Spitzer has sent back to Earth over the past 13 years are spellbinding. Swirls of neon purple, green, red, blue and pink, contrasted against the darkest of black of the universe.
But it will still be some time before Ms Bernard and Dr Trenti can properly process all the data that will eventually create those stunning images. At the moment, their images look like large splotches, with no discernible detail.
But these splotches are fascinating to Ms Bernard and could hold some vital clues that could answer some of humankind’s most profound questions.
“We have a basic idea of what this galaxy should look like and so we basically comb through this image and see if we can match it with these ideas of the galaxy,” Ms Bernard says.
“Finding these first galaxies tells us a bit about what the universe was like at that time, because we can look at what the properties of the galaxy are, what sort of stars it has inside it and we can get an idea of how these processes we see in the universe today, like galaxies merging, all started.”
Exploring the early universe and getting so close to the Big Bang is at the centre of Ms Bernard and Dr Trenti’s research.
“It’s really to address one of the most fundamental questions: where did we, humanity, come from?” Dr Trenti says.
“After the Big Bang, the universe was a pretty dull place; it was only hydrogen, helium and traces of maybe a few heavier elements such as lithium, but nothing else.
“With time, tiny fluctuations in these elements grow and gravity makes them collapse and you have the physical conditions that lead to the formation of the first generation of stars and galaxies. And those produce chemical elements through fusion processes and then you have the elements – carbon, oxygen, iron – that are necessary for life.”