From Blebs to Blobs with Christopher Charles

Detecting live, rare atoms is challenging work – even when you work with accelerator mass spectrometry at the University of Toronto's IsoTrace Laboratory.

"Rare atoms were produced in meteorites or natural geologic samples by processes including supernova explosions or cosmic ray spallation," says Postdoctoral Fellow and Lecturer Christopher Charles. "Some of these atoms may still exist 'live' in natural materials, however they exist at extremely low levels and it is very difficult to detect these atoms in natural geologic samples due to the overwhelming background 'sea' of other atoms that tends to drown them out."

Charles is developing new instrumentation and techniques to find these rare atoms - technology that can be applied to meterorites, environmental samples and even to medical research. And, on May 22, he'll offer members of the public a glimpse at some of the challenges involved in understanding and interpreting the composition, structure and formation of meteorites.(Read more about his talk.)

It's the latest in a series of talks at the Toronto Public Library, organized by Professor Ray Jayawardhana, senior advisor to U of T president David Naylor on science engagement. Charles spoke with U of T News about his upcoming talk, and about teaching and conducting research at U of T.

What drew you to this area – and to this particular focus?

Intellectual curiosity and the difficulties of rare atom detection. Meteorites are extremely valuable and unique rocks - think of them as early Solar System time capsules that tell you what the early Solar System was like over 4.5 billion years ago. Each part of a meteorite is like a page in the history of our Solar System. So holding a meteorite is a very humbling experience, since that little piece of rock has witnessed more than any other rock. The hard part is understanding how to read the book since its very easy to skip words, pages, or chapters.

What drew you to U of T?

My interest in U of T is traceable back to the first time I visited the university as a grade nine high-school student where we were given a tour of the IsoTrace Laboratory (oddly enough). I was absolutely awestruck seeing the IsoTrace 3-million volt particle accelerator - that huge and complex machine made an immediate and everlasting impression. I had absolutely no idea what it did or what it was, but I immediately thought it was the coolest thing I had ever seen and knew that someday I wanted to do something with it. That visit to U of T and IsoTrace was enough to cement my interest in science, and gave me a desire to work with atoms and electronic gadgets. Throughout high-school I then developed a fascination with radioactive beam instrumentation, mass spectrometry and the scientific problems that could be explored by studying atoms. I eventually completed an Hon.B.Sc. in astrophysics at U of T where I did a thesis project at IsoTrace using the accelerator.

For my graduate degrees (masters and doctoral) I stayed at U of T but switched departments and became a geochemist at the Jack Satterly Geochronology Laboratory. Switching departments was almost like switching schools, since geologists have a much more "down to Earth" point of view about the analysis of natural materials and the use of mass spectrometry than physicists. This was an important and necessary change for me, that gave an appreciation to look at problems in planetary science from different and sometimes opposing points of view. Staying at U of T for my graduate work was a decision I made due to the incredibly abundant and diverse resources at this university, and the exceptional colleagues and friends that I had developed over the years.

What is it like to conduct lab work?

It is a wonderful and liberating experience to have the freedom to study new, unique and hard problems in the lab. I particularly love the creative aspect of lab research — where you have almost no bounds on inventing new interdisciplinary ideas, theories, solutions or instruments to tackle any number of problems. Like most of us, I typically approach problems from previous experience and intuition; however, experience and intuition are often wrong! There are a few seasoned souls at U of T who instead approach problems very rationally and logically with an open mind. This is a hard thing to do, so I've tried to learn from those brave people. When doing lab work with isotopes and mass spectrometry, it is important to learn from one's mistakes and misconceptions, and accept the mistakes and misconceptions of others. But is is also essential to devote yourself with the highest attention to detail and concentration since careless mistakes will ruin not only your work but also that of your peers. Thus I've found that lab work should be approached from a mindset that considers not only my needs, but also the needs of others and the integrity of the laboratory. The payback is that something new and exciting could be discovered.

And teaching?

Teaching has been my single most rewarding experience at U of T. There is no better feeling than when students approach you after class, in the hallway, or at office hours and express a genuine interest and curiosity in what you just taught. This year I've had a few students who were considering switching their major to geology after taking my introductory geology course. That makes it all worth it. The greatest privilege a university researcher can have is to be that person who helps students through interesting and tough scientific ideas, that could spark a lifetime career interest. Thus with teaching comes a great responsibility to your students.

Do you involve students in your research? If so, can you give us a sense of what that means for them?

Yes, absolutely. Students are full members of the university and must always be involved in research as much as possible, the sooner the better. In a university environment, research is the best way for a student to find what they like or dislike and where their strengths and weaknesses lie. This is because research demands long hard work and thought, so a student will come to see if they either love or hate a given project. Being part of a research group teaches important life lessons including independence and responsibility, and gives a strong sense of belonging, purpose and confidence to a student. This is where U of T is exceptionally unique since there are so many excellent research options and resources. For me to take on a student in my research all I want to see is a genuine interest and drive. I'll do the rest!

Can you give us a glimpse of what your Toronto Public Library audience can expect?

The library talk focuses on a project I did a couple years ago that applied medical 3D X-ray microcomputed tomography to study the shapes and structures of "blobs and blebs" (chondrules and metal) in a meteorite from the Royal Ontario Museum. Chondrules are millimeter-sized spheres made of metal and silicate minerals, that formed free-floating in the early protoplanetary disk, after the Sun formed but before the Earth formed. Chondrules are among the oldest known natural objects in our Solar System and thus provide a rare and unique geologic record of the astrophysical environment in the protoplanetary disk over 4.5 billion years ago. Chondrules have been well known to meteoriticists for around 200 years, but their formation and significance is poorly understood in general, because chondrules can have diverse and complex geochemistries. Some chondrules have very complex shapes and structures that are poorly understood.

What I did was to study the 3D shapes and internal structures of chondrules using microcomputed tomography. This was somewhat unusual since tomographic scanners are a medical imaging tool rather than a geological technique. However, it is possible to image meteorites in these instruments, thus the goal of this project was to see if the 3D shapes and structures of chondrules offered any new information on the conditions that existed in the nebula when they formed. Indeed, this was the case but, as the talk will discuss, interpretation can be rather tricky. So the talk will describe the project, present the 3D shape data in a non-technical way, and offer two interpretations that are currently being debated.