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GLAS Education’s tactile telescope cannot be used to gather light. But as a teaching tool, it is quite enlightening.

Imagine a telescope with a section cut away. Students don’t look through it, they look into it – or feel inside it. The ingeniously viewable scope came out of a project called Innovators Developing Accessible Tools for Astronomy (IDATA), which was funded through a National Science Foundation (NSF) grant. One of the goals of IDATA was to make astronomical information accessible to blind/visually limited students.

The late Kevin McCarron and GLAS volunteer Ed Sadler, both retired high school science teachers with workshop skills, took it upon themselves to create a tactile telescope. Copies of the plans to build the McCarron-Sadler Tactile Telescope are available in PDF at https://glaseducation.org/able/.

Youngsters are particularly intrigued by the workings of a telescope, said GLAS Education Director Kate Meredith. And in their desire to learn, they want to touch and feel the devices.

“Typically, our volunteers and staff don’t like it when people touch their telescopes, especially the lenses and the mirrors,” Kate said. “So we needed a telescope that we could touch.”

McCarron, who passed away in 2020, taught science at Oak Park and River Forest High School in Illinois, was a talented craftsman with a workshop at Yerkes Observatory. In 2017, he created the touchable telescope, using pieces of PVC plastic pipes, scrap wood (properly fashioned) and springs and screws from a hardware store. McCarron’s prototype is still a GLAS treasured possession.

Sadler, a retired science teacher who taught at high schools in Williams Bay and Elkhorn, and a long-time and continuing GLAS volunteer, took on the task of creating a simpler version of McCarron’s design and then writing concise, easy-to-follow instructions for its construction.

Dark haired woman in a white sweater sitting on a couch with a gray-haired, bearded man in glasses with a white and black tube lying across his knees.
Kate Meredith, left, GLAS director, talks with Kevin McCarron, maker of the original tactile telescope prototype, in a video made just before his passing in 2020.

Ed said McCarron’s model is a work of art, but it would be difficult and expensive to recreate. McCarron’s prototype used some real components, like lenses, mirrors and a telescope focuser.

“It became apparent that some of the pieces would be hard to come by,” Ed said. “We decided that perhaps we should make it more accessible for people to put together.”

Anywhere from 2-feet to 6-inches long and with a diameter of 4-inches, the tactile telescope now available from GLAS Education are patterned after a Newtonian reflector telescope. GLAS wants to distribute the tactile telescope instructions to educational institutions so schools and museums can create their own tactile telescopes.

In a video made prior to his passing in 2020, McCarron pointed out that his telescope is not real, but a model. As a teaching tool, it is important to consider objectives before creating anything. McCarron did just that, making every feature of the telescope available for exploration.

“Does this telescope work? No. In fact we made it so it does not work,” McCarron said. The telescope parts are spaced out so it’s easier to explore the components visually and with hands and fingers, he said.

A seated, smiling older man in glasses and baseball cap holding a white tube with orange plastic components onm his knee.
Ed Sadler, a GLAS volunteer and retired science teacher, crafted a simpler version of McCarron’s tactile telescope and wrote simple instructions for building one.

Many of the parts can be made from items available at hardware stores, like PVC tubing, standard screws, and wooden doweling. Ed said that in the years since McCarron made his model, 3D printing has become more common. Most educators and model makers can do their own 3D printing or know someone who can, Ed said. For example, instead of real mirrors and lenses, the mirrors and lenses in Ed’s version are opaque plastic. The faux lenses and mirrors are 3D-printed discs made concave and convex like the real mirrors and lenses. And they are accessible to the touch.

Ed didn’t do the work alone. He needed help with the 3D printing, and James Cudworth provided that assistance. James is the son of Kyle Cudworth, retired Yerkes Observatory astronomer and former observatory director. James learned 3D printing in the observatory workshops and he remains a frequent volunteer at GLAS Education. James said he stopped by GLAS one day to deliver cookies – or something – and got lassoed into the project.

It wasn’t difficult, he said. “I put it on freeCAD and got it printed,” he said. “It went pretty smoothly.”

Student volunteer William “Liam” Finley of Lake Geneva helped out as well, working out the construction of the telescope’s main focuser in the eyepiece. According to Ed, Liam figured out some of the trickier aspects of building the focuser.

Ed took the pieces, hardware and printed, and built a new, 16-inch prototype tactile telescope. That became GLAS’s traveling telescope, going with Kate to American Astronomical Society conferences and accessible education workshops around the country. With GLAS producing more of the tactile telescopes, GLAS staff can take copies to workshops around the country where the curious can lay their hands on it.

Ed and GLAS staffers Adam McCulloch and Chris Schultz have also finalized instructions so others can build their own McCarron-Sadler Tactile Telescopes. With the tactile Newtonian telescope instructions now complete, Ed and Adam are working at creating tactile models of other kinds of telescopes.

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