Galileo did not invent the telescope, but he did engineer it into a precise scientific instrument. By grinding and refining his own lenses to increase their magnification, he was able to make observations that challenged the longstanding belief in a stationary earth. In astronomy, as in many other fields, engineering and science are locked together in a very close embrace.
University of Notre Dame students, Peter Verges, a junior majoring in aerospace engineering, and João Pedro Ferreira Gil, a sophomore majoring in applied and computational mathematics and statistics, discovered this for themselves by designing and building their own 10-inch Dobsonian telescope.
“Large scale scientific experiments such as the James Webb Space Telescope, require close collaboration between scientists and engineers,” said Paul Rumbach, associate teaching professor in aerospace and mechanical engineering as well as the students’ advisor for the telescope project. “The astrophysicists lay out the overarching scientific objectives and design criteria, while engineers handle more specific details for design and construction. Building their own telescope provides students with a micro version of this process.”
Telescopes collect light from many points on celestial bodies such as the moon. Mirrors redirect these incoming light rays so that light from each point converges to form an image, which can then be magnified.
Building their own telescope required Verges and Ferreira to do extensive design and fabrication work. Verges used Autodesk Fusion to design the telescope tube sections and the secondary mirror mount—a component which must be precisely engineered so that the mirror successfully redirects light toward the eyepiece.
“The 3D printers in the Engineering Innovation Hub (EIH) were not large enough to print a full tube section of the telescope,” said Verges. “We had to make a way for the tubes to be printed in separate parts and then connected to each other. So, we made the interlocking dovetail design that you can see on the telescope. This was further complicated by the tube sections being curved, but the dovetails were successful.”
The components of the telescope’s base—two side panels and two circular plates—were also designed in Fusion, but water-jetted, rather than 3D printed, from HDPE, a strong and durable plastic.
Ferreira worked primarily on the telescope’s optics. “The most difficult parts were achieving proper alignment between the mirrors and finding the exact focal distance,” he said. “Proper collimation [alignment] ensures that light travels in a perfectly straight path through the telescope to produce images that are crisp, not blurry or distorted.”
Verges and Ferreira grew up in very different parts of the globe—Verges close to New Orleans, Louisiana and Ferreira in Betim, Brazil. Yet both developed an early passion for studying the night sky that’s led them to pursue careers in the space industry as undergraduates.
Building their own telescopes not only fulfilled their childhood dreams, it also reshaped their understanding of engineering and experimentation. Verges said he learned that “reality often is not as exact as our 3D models,” and that he needed to “learn how to better anticipate those differences.” Ferreira noted the challenge of dealing with things outside your control—such as the weather in Northwestern Indiana.
“It’s almost always cloudy and too cold to stand around outside with our telescope.” In the end, he said, “that taught me that sometimes things don’t go as planned—and that’s okay.”
Ferreira and Verges are planning to continue their observations of the night sky during the spring semester, patiently awaiting a break in the clouds.
—Karla Cruise, Notre Dame Engineering
From left: João Pedro Ferreira Gil, Professor Paul Rumbach, and Peter Verges.