How engineering, logistics, and a passion for deep-sky observing led to the creation of our giant Dobsonian telescope
In astronomy, aperture matters.
The larger the telescope, the more light it collects and the more details we can see in distant galaxies, nebulae, and star clusters. For many astronomers, using a large telescope is a dream. Designing and building one from scratch is an entirely different challenge.
After working as a mechanical designer for almost twenty years, the engineering itself wasn’t the most difficult part of the project. The real challenge was something else entirely: combining the desire to build a very large telescope with the practical constraints of transportation, daily setup, and professional use.
This telescope was never intended to be a hobby instrument used occasionally. It had to work as a professional observing telescope, something we could operate every night during our astronomy experiences on the slopes of Mount Teide, one of the best locations in the world for stargazing.
And that requirement defined the entire design process.
The First Challenge: Transporting and Storing a Giant Telescope
Before thinking about mirrors or optics, we had to solve a much simpler problem: where to store the telescope.
Our astronomy activity is a small family-run business, so building or renting a dedicated observatory or warehouse was not financially realistic. The only viable solution was storing the telescope in the garage of our house during the day.
However, in Tenerife houses with garages are surprisingly rare. This immediately created a set of physical constraints that determined the maximum possible size of the telescope:
- The telescope had to fit inside a van
- The van had to fit inside our garage
- The telescope had to be transported safely and quickly every day
This logistical limitation ended up becoming the starting point of the entire engineering project.
Designing the Telescope Starting From the Van
Once we found a house with a garage large enough for a van—and enough extra space to use as a small workshop—the real design work could begin.
The very first thing I did was open my CAD software and model the interior volume of the van.
That digital model became the maximum transport envelope for the telescope.
Initially, the dream was ambitious: building a telescope with a 1-meter primary mirror. But even a quick estimate showed that the mirror and its support structure alone would weigh around 200 kilograms.
That immediately ruled out the classic approach used by most large amateur telescopes: fully disassemblable structures.
Even if the telescope could be taken apart, the heaviest component would still be impossible for one person to handle safely.
So the design philosophy changed completely.
Instead of a modular telescope assembled piece by piece, the instrument had to be a single integrated structure equipped with its own assisted mobility system, allowing it to be moved safely and efficiently.
Why a Dobsonian Telescope?
Over the last 25 years we have used many different telescopes during public observing sessions. From that experience, one design proved consistently superior for visual astronomy with guests: the Dobsonian telescope.
This type of telescope was popularized in the 1960s by John Lowry Dobson and remains one of the most efficient designs for large-aperture instruments.
A Dobsonian telescope combines:
- Newtonian optics, originally developed by Isaac Newton
- A simple alt-azimuth mount, moving up–down and left–right
This configuration is mechanically simple, extremely stable, and incredibly intuitive for public observing sessions. For sharing deep-sky objects with visitors, it remains one of the best solutions ever invented.
For this reason, the optical tube assembly became the first component to design, since it determines the overall dimensions of the entire telescope.
When the CAD Model Meets Reality
The first conceptual design was based on a 1-meter mirror.
But once the optical tube was modeled in CAD and the rest of the structure was added—including the mount and the integrated transport system—it quickly became clear that the telescope would simply not fit inside the van.
Fortunately, parametric CAD modeling allows rapid adjustments.
By progressively scaling down the design and constantly verifying the available transport volume, the optimal size slowly emerged.
The largest possible mirror diameter that satisfied all constraints was: 82 centimeters.
Or, using the units preferred by optical manufacturers: 32 inches.
A Telescope Far Larger Than Commercial Instruments
Even though we had to abandon the idea of a full one-meter mirror, the final result was still extraordinary.
A 32-inch mirror has a light-collecting surface four to five times larger than the biggest telescopes typically available on the commercial market and eight to twelve times larger than the telescopes used by our competitors in Tenerife.
This enormous increase in light-gathering power allows us to show galaxies, nebulae, and star clusters with a level of brightness and detail that most visitors have never seen before through a telescope.
Today, this telescope is the centerpiece of our observing experience, the Grand 32″ Scope Adventure, where guests can explore the deep sky under the pristine skies of Tenerife.
But defining the aperture was only the first step of the project.
A giant mirror is useless without a structure capable of supporting it with extreme precision while remaining portable, stable, and lightweight enough to be transported every day.
Designing such a structure required combining very different materials, advanced vibration control, and a completely custom mechanical system.
In the next article, I’ll explain how the engineering of the telescope structure evolved—from the mirror cell to the carbon fiber truss and the motorized transport system.