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Nishant Shirodkar: This IS rocket science

The following story was written in April 2019 by Kendall Hoggard in ​ENGL ​4824​: Science Writing ​as part of a collaboration between the English department and the Center for Communicating Science.

This photo shows a young dark haired man wearing glasses and and a gray suit. He is standing in front of a research poster and smiling at the camera.
Nishant Shirodkar (photo courtesy of Nishant Shirodkar)

Early detection sensors do a lot for the systems they are installed in. They can warn of future costly repairs and help to prevent disasters--especially if the sensors tell us about the volatile materials used as rocket fuels. This is what Nishant Shirodkar is trying to perfect in his lab. The applications for these sensors are endless.

    Shirodkar came to Virginia Tech for graduate work after completing his degree in mechanical engineering. Now working under Dr. Gary D. Seidel, he is researching how to make an effective sensor system that will detect damages in crystalline materials.

    The main focus of the research is to detect damage in solid fuels that are highly volatile. To research this, the lab team creates their own polymers that would hold these solid fuels, but they remove the volatile fuels for safety reasons.  They then mix the polymer with carbon nanotubes. The nanotubes are a different formation of carbon atoms, similar to how diamonds and graphite differ in structure but are still made of carbon. 

This black and white photo shows an undulating surface adorned by wavy tendrils. Probably an transmission electron micrograph of the carbon nanotubes discussed in the story.
Carbon nanotubes (magnification 50,000x). (Photo credit: Nishant Shirodkar)

    These nanotubes have electrical conductivity and, when added to the polymer, they create a material that has a resistance that can be measured. After measuring the  resistance of the newly created material, the lab team applies stress to it, either by compressing it or stretching it, to cause microfractures in the material. Then the material has its resistances measured again, and the changes are documented and the microfractures observed.

    This test is repeated over and over to compile a database that can relate damage to changes in resistance. The idea behind this, Shirodkar explained,  is that these sensors can be running constantly and computers can keep an  electrical current through the material, constantly measuring changes in resistance and checking for damages in the material.

    To put the importance of this into terms I could understand, Shirodkar explained to me how volatile rocket fuels could be. The process for just loading the fuel into the rockets is a tedious and time-consuming event. The fuel has to be carried very slowly, which can take days, so as to prevent damage to solid fuels or combustion from liquid ones. 

This photo shows a 10,000 times magnification of a structure that is cracked. This is probably a transmission electron micrograph of the polymer material described in the story.
Microcrack (magnification 10,000x). (Photo credit: Nishant Shirodkar)

    As of right now, there really are no sensors in place that track any type of fractures in crystalline fuels to a degree as sensitive as Shirodkar’s research would allow. The system he’s working to develop measures fractures that are nanometer thickness, which can prevent bigger and more dangerous cracks and damage from occurring.

    In the case of solid fuels, this can prevent wasted time and wasted product. When these volatile solids are damaged in certain places, they can cause chain reactions that can cause the rest of the fuel to expend its energy, causing further explosions. This would leave the fuel in a state that is either unpredictable or depleted to the point that it would not put out the amount of power that was expected.

    When it comes to space travel, we need everything to go as smoothly and as predictably as possible, and Shirodkar’s sensors are a great way to assist in that.