Sounds of the planet

Acoustic remote sensing and its uses in underwater environments

Topic: From the lab

Acoustics - From the deep sea to outer space

  , , ,

📥  From the lab

Asteroids near Earth

"In space, no one can hear you scream" ,,, This was the motto from the first Alien movie and it has been used and abused in the decades since. I lost track of the number of times I have worked on ships and seen T-shirts or posters with "In the deep sea, no one can hear you scream ..." or similar. Although sound travels very well in water (and better than in air) ...

So how would it work in space? Sound does not travel in vacuum, despite what countless movies seem to imply (and yes, I love the sound effects of Star Wars or Farscape, even if I need to leave my scientific mind aside for a time). But space is made of much more than vacuum.

There are planets, first, and some of them are getting increasingly closer as plans for their exploration are firming up. Elon Musk gave a much talked about presentation at the International Astronautical Congress in Mexico last week. I was interviewed on Al Jazeera to talk about the actual feasibility of the scheme, and this still seems rather far off. The exploration of Mars, which needs to take place before any attempt at colonisation, will need to include assessing potential resources in the ground. We know there is water below the surface, from remote sensing by satellites in orbit around Mars. And there are very strong indications that some of this water is still freely flowing at the surface in specific areas. But what about other deposits, for example oxygen? How easy would it be to drill and get it? How stable would exploration platforms, or habitats, be as resources get extracted from below them? Like on Earth, these questions can be answered directly with acoustics. Sending sound waves of different frequencies through the surface, we can listen to their returns and find out how deep they are, and what they are made of. Just like seismics or non-destructive imaging (think about ultrasound scans of human bodies ...)

Planets are great (I love planets) but they are far away, expensive to get to, and with the current state of space exploration programmes, it will be a while before we can get more than passing glances at their marvels and really explore them. Closer to home, though, we have asteroids and comets. They are big pieces of rock or gravel (comets are often compared to "dirty snowballs"). They contain all sorts of minerals and oxygen or frozen water. And they often pass in the neighbourhood. So what about exploring asteroids?

Asteroids near Earth

Asteroids often come to the neighbourhood of Earth. Artist's view from the European Space Agency (Copyright ESA - P.Carril).

This seems much more feasible, and there are actually several companies aiming to mine asteroids for their riches. These companies have been in existence for several years, so they are no "seven-day wonders" but real companies, with serious investors. The government of Luxembourg recently announced it had its own plans to support space exploration and space utilisation. And they organised a great workshop two weeks ago, inviting space industries to meet space scientists. It was a packed programme over two days, with world-famous scientists describing the main discoveries of recent missions to asteroids and comets, and their plans to learn more over the coming years. The ASIME-2016 workshop is now leading to a White Paper, which will lead to recommendations on space mining, the science behind it but also the implications for protection of any possible astro-biology (none found yet, but one can hope ...). I was there to present seismo-acoustics to a different audience, and it was very encouraging to see possible avenues for acoustic exploration of still mostly unknown planetary bodies ...

Once we get to them ... (but at least we have the tools ready ...)



Newborn icebergs - A fresh start to 2015

📥  From the lab

Having fun in the field is one thing. But to have impact, and be really useful, this research also needs to be published. This is where the hard work continues.

Led by Oskar Glowacki, a young and promising glaciologist from Poland, one of our articles was recently published in Geophysical Research Letters, the prestigious journal of the American Geophysical Union. And they liked it so much that it is now featuring on their own blog.

The YouTube video shows examples of glaciers collapsing, and what they sound like underwater. We are meeting in Poland in two weeks to discuss the rest of the analyses, and how we will follow this up, in publications and in the field. Stay tuned 🙂

The Sound of Silence

📥  From the lab

Logo of EC SITAR project

The European SITAR project used sound to detect toxic buried waste at sea. Logo drawn by Peter Dobbins.

Sound is the most useful tool to investigate the world's oceans; it is also used in medical physics, for example for ultrasound scanners. The image above is a nice picture drawn by my colleague and friend Peter Dobbins when he was working with us on the SITAR project, a European collaboration to detect toxic waste buried under the seabed and how risky it was.

But sound is much more than just a tool. It also holds beauty and variety. I was recently invited to write a review for “Sonic Wonderland: a Scientific Odyssey of Sound”, by Trevor Cox. This was a beautiful book, and it invites us to celebrate the richness of sounds all over the world, from home to far away, sometimes below our feet or high up in mountains. More details about the book are available in my review, published by Physics World in its December 2014 issue . This book is a must-read, written by one of the true experts ... And a good gift for the coming festive season too ...