The future of long-duration deep space travel hinges on solving many problems related to microgravity, a unique environment that determines how humans will have to adapt to life and work far from Earth. 

At the School of Engineering, Research Assistant Professor Jannatun Nawer, EG06, EG18, is working closely with her Ph.D. advisor and Professor of Mechanical Engineering Doug Matson to contribute solutions that will help with one of those problems: in-space manufacturing. 

The Tufts engineers are developing new alloys—metals made by combining two or more metallic elements—that could help future astronauts repair their equipment and fabricate new parts. The Tufts research is funded by NASA.

Repair challenges that might be solved on Earth by standard tools (and the convenience of a hardware store) are complicated in space by microgravity. Weightlessness, just as it affects human bodies, also affects how the materials in tools and other equipment behave.

Testing materials for use in space is exacting work. Over the past several years, the Tufts team has undergone a rigorous process to qualify alloys for experiments on the International Space Station. Round one is testing of alloy compositions at NASA’s Marshall Space Flight Center in Huntsville, Alabama, where an electrostatic levitation process allows an ultra-pure study of materials under high temperatures. 

The next step is a parabolic flight that simulates the weightless conditions of deep space through maneuvers that alternate ascents and descents (U-shaped parabolic curves) with level flight. On parabolic flights, periods of free fall recreate weightlessness for 22 seconds and are repeated 31 times. “If we're going to go beyond the surface of the Earth, we need to do parabolic testing first,” said Nawer.

This September, Nawer experienced her first parabolic flight as co-principal investigator on NASA-funded research on Inconel, a super alloy found across a range of industries. As part of that role, she joined the flight and technical crews in the experimental area to observe test conditions for the Tufts-designed alloy, her legs secured for safety. (After testing, she had the chance to join others in a “free-floating” zone, “the closest I’ve been to being an astronaut!” she said.)

Tufts has been conducting parabolic testing in Europe since 2014 when Matson flew during an investigation of the solidification of structural steel alloys.  The experiment in September of this year, organized by the German Aerospace Center, was one of eight experiments included on an Airbus A310 ZERO-G flown out of France’s Bordeaux–Mérignac Airport.

On learning that she would join the flight, “I was ecstatic,” recalled Nawer, who grew up in Bangladesh with dreams of being an astronaut and earned her undergraduate degree in aeronautical engineering.

During the flight in September, the Tufts sample was tested during 10 of the 31 parabolic trajectories. Nawer’s main goal was to study physical properties such as viscosity, surface tension, density, and electrical resistance.  She was also poised to modify any experimental parameters if needed, but all went smoothly. The results of the experiment are still being analyzed.

At the heart of the parabolic flight experiments is an ultraclean chamber known as an electromagnetic levitation facility. The device, which can process metallic samples up to 2400°C, allows the contactless study of thermophysical properties and microstructures of hot and highly reactive molten materials. 

Such tightly controlled and high-stress variables make possible observations that aren’t available on Earth, where gravity can modify results, Nawer said. 

On the ground, gravity’s force turns a molten sample that’s expected to be a spherical shape into “an inverted tear drop,” she said. “This is why we go to space. Once the sample melts in microgravity, there's no gravitational force. The shape is spherical. It gives us multiple advantages because now we have a sample that allows us to perform different types of tests.”

Matson said the flights reveal changes that occur during convection, or heat exchange, during a “melt” under microgravity conditions. 

“My interest is what happens during solidification,” he said. “If we change the composition of our material slightly, those kinetics will change. By investigating these changes in flow patterns, we can get closer to what’s going to be effective when manufacturing in space.”

Learning how an alloy will behave will help future space crews have reliable and safe manufacturing, he said—and understanding convection more fully can also make manufacturing on Earth better.

The basic science being conducted as Tufts contributes to efforts by researchers from various backgrounds to design alloys for use in space, Nawer said. “You will need to know about existing alloys and how they behave so you can then develop new alloys from them,” she said. “That means we simplify: If an alloy has 11 elements, we simplify it and see if we simulate a similar performance with just three elements.”

Her parabolic flight experience was particularly meaningful because it advanced her scientific goals. “If I wanted to just experience the fun of a free fall, there are commercial flights that would have made that possible,” she said. “But bringing my research into that environment and being part of work that's so interesting to me and to my lab—that gives me a tremendous sense of accomplishment.”