Seery Chen, a student at the University of Toronto, got in touch about their Raspberry Pi-powered PhD thesis project: a telescope called the Dragonfly Spectral Line Mapper.
Yes, we’re pretty sure the design is named after real dragonflies due to their cool compound eyes which look like millions of lenses all smushed together.
Dragonfly design inspiration
The design is based on the Dragonfly Telephoto Array, which was developed to find clues to the distribution and nature of dark matter in the universe by imaging faint and spread-out objects in the sky. The original Dragonfly is a telescope made up of a mosaic of Canon telephoto lenses on two mounts. The lenses all point to the same target in the sky: adding together all the images from the mosaic of lenses makes Dragonfly the equivalent of a one-metre telescope. One of those would usually have a starting price of around $500,000.
Looking at intergalactic gas
While the original Dragonfly was built to look at starlight, the Dragonfly Spectral Line Mapper looks at gas. Special filters were added to target a specific wavelength of light, allowing imaging of the “glow” of gas around galaxies. The gas this Dragonfly is looking for is what’s called the circumgalactic medium; this is a huge reservoir of gas and plasma that surrounds a galaxy. The circumgalactic medium can act as a sort of barrier between galaxies themselves and the space between them, which is sometimes called intergalactic space. The circumgalactic medium is really diffused and faint, making it difficult to observe, but the combined strength of Dragonfly’s multiple lenses and the special filters mean that not only can you observe this elusive gas, but you can also take a picture of it.
Switching in Raspberry Pi
Adding the gas-seeking filters to the original Dragonfly design wasn’t the only change Seery’s team made; they also chose to switch from Intel Compute Sticks to Raspberry Pi. Each lens of the new design acts as an independent subsystem with its own focuser, camera, and Raspberry Pi computer.
Two of the four mounts that will eventually make up the Dragonfly Spectral Line Mapper are built and ready. The final two are planned for completion this summer.
Research papers for further reading
Exciting images of galaxies taken by the Dragonfly Spectral Line Mapper don’t yet exist, but the team’s prototype collected quite a lot of data on the M81 and M82 group of galaxies. You can learn more about it from these two papers by Seery’s colleagues:
NASA also has a short explanation of how the two galaxies have been “locked in gravitational combat for a billion years.” We do love NASA; so dramatic.
Seery has also written up a conference paper about the project, and while the official version is behind a paywall, the preprint version is open access: The Dragonfly Spectral Line Mapper: Design and First Light.