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Advanced materials from space: Where it all began

Posted March 5, 2013
Test particle image, supplied by Milos Toth and Aiden Martin

Test particle image, supplied by Milos Toth and Aiden Martin

The origin of our universe remains a mystery, but that may soon change. In collaboration with the National Aeronautics and Space Administration (NASA) and with funding from the Science and Industry Endowment Fund (SIEF), physics PhD student Aiden Martin is developing a technology that processes advanced materials from space. His work may, one day, help solve the cosmic mystery of how our solar system was formed.

In 1999, NASA launched the Stardust mission in which a robotic space probe was sent to collect and intercept particle samples from the comet Wild 2. The comet fragments were imbedded into silica aerogels – a light, low density, solid foam-like substance – and returned to Earth for analysis after a seven-year round trip.

Since then, international teams of scientists have been examining the particles. However, many questions remain unanswered. While NASA’s main objective is to learn about the origins of the solar system, Aiden Martin’s work is aimed at using advanced nanotechnology techniques to remove the particles from the silica aerogels, without damage to their original state, for further analysis.

The second-year PhD student was recently awarded a competitive SIEF John Stocker Postgraduate Scholarship which will enable him to work on a special research project motivated by NASA’s Stardust Project.

The scope of Martin’s PhD project originally came from the work of two senior researchers – the Harvard-Smithsonian Center for Astrophysics’ Eric Silver and UTS Professor of Physics and Advanced Materials Milos Toth.

Silver and Toth have been collaboratively working together on electron beam induced etching and x-ray analysis, two techniques that are key to Martin’s research, for over six years. The pair met in 2005 when Toth was working for FEI Company – a world leader in electron microscopy technologies, based at the Harvard-Smithsonian Center for Astrophysics.

Using funding from NASA, FEI Company and SIEF, they were able to find, and fund, the right PhD candidate to apply their research to, and contribute to the objectives of, the Stardust mission. Their aim is to develop a technology that can analyse the cometary particles from space.

Martin’s project is specifically looking at the development and technological application of advanced materials.

He explains: “Once the samples were brought back to Earth, the challenge has been to remove the tiny particles from the encapsulating aerogels in a non-destructive way so they can be studied and analysed, by scientists, to determine the make-up of different materials in space.”

To do this, Martin will use an electron beam to chemically etch the advanced materials and look at the reactions that take place when different gases are applied. At a fundamental level, what he is interested in is how these gas molecules interact on different surfaces and what happens when they are exposed to electrons, ions and lasers.

“If an electron beam is directly put onto a material it may not do anything,” says Martin. “But by adding an appropriate chemical in the form of a gas there may be an interaction between the beam, the chemical and the material. This can result in vapourisation, or the removal, of the material, like the aerogel, under the beam.

“This is called electron beam induced etching. By using this technique in an electron microscope we can study a lot of interesting chemistry and physics that underpin many processes used in nanotechnology.”

To conduct his experiments and perform his research, Martin has been using the high-powered FEI Company scanning electron microscope (SEM).

He says, the “FEI Company is an official collaborator on this project as most of my research will be carried out using their world-leading electron microscopy technologies that are housed at UTS.”

Utilising the SEM to perform the electron etching technique Martin has been able to remove the aerogel foam without attacking or damaging representative test particles. The particles can then be subsequently analysed by Silver from the Harvard-Smithsonian Center for Astrophysics.

“The gases that we’ve been using can’t really be put under a normal microscope; they’d literally eat the microscope away,” says Martin.

“We need to extract these particles out of the aerogel and determine whether they are going to be contaminated, or damaged, by the electron beam or the gases we are using to remove them.

“The gases also have the potential to etch the particles, so we need to make sure we are using the right chemistry and the right process to ensure the cometary particle is still in pristine condition for further analysis.

“The FEI equipment,” adds Martin, “enables us to expose the nanoparticles in a way that is reproducible and reliable for analysis.”

The young scientist’s work has a secondary benefit too. “An extension of my PhD project is to work with FEI to develop and improve the processes of electron beam induced etching which is one of the advanced techniques used to extract advanced materials without changing the original state of the particles.”

Though Martin’s research is still in its infancy, and there is still much work to be done, his test samples are already producing some outstanding results. He expects the project to take a further 18 months before the extraction technique can be fully verified.

Source: University of Technology Sydney

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