On a crowded planet, astronomers are continuously seeking out pristine locations with low pollution levels (e.g. from light, radio interference, and unwanted chemicals) as well as excellent weather and atmospheric transmission. Logically, such sites typically have reduced access to industrial facilities such as electrical power. Moreover, we have a duty to preserve these sites both as guests in such locations and for future generations to appreciate.
The Atacama Large Aperture Submm Telescope (AtLAST) project hopes to serve as an example of sustainability, taking our responsibility seriously from inception to every stage of the project: construction, power generation,1 remote operations, improvements in daily usage, and by providing a long-lived, sustainable and upgradeable facility. One of the several such innovations will be a regenerative braking system, akin to those in electric cars, that both recovers > 60% of the kinetic energy typically wasted as heat when the telescope decelerates, and reduces the scale of the power generation facility required to accelerate the structure quickly.
AtLAST is a massive, 50-meter diameter concept for a next generation submm (30-950 GHz) facility with a field of view orders of magnitude larger than the current generation of > 10-meter survey experiments.2 The current design is over 4000 tons, implying a proportionally large inertia. Simply accelerating the structure would require megawatts of power production, but the good news is that the design is relatively low friction. AtLAST will be able to recover the vast majority of kinetic energy with a simple but very effective modification to the standard drive: a bidirectional DC-DC stage that charges a super-capacitor (aka “supercaps”) bank during braking and reuses the recovered energy for the next acceleration burst. Supercapacitors provide very high instantaneous power and can tolerate millions of charge–discharge cycles; their comparatively low energy capacity is sufficient because only the subsequent slew or scan motion must be covered. The system is described in detail in the following research paper: Kiselev et al. 2024.3
The benefits do not stop there, however! From a power generation perspective, we can expect the power demand to be more stable and the peak demand to be significantly lower, as the supercapacitors effectively shave the power peaks by pre-charging for the next burst of acceleration. This allows all related electrical components – such as transformers/converters, cables, etc. – to be downsized. In summary, the proposed kinetic energy recovery system will substantially reduce the overall energy consumption of the telescope drive system – a significant consumer in most observatories – and cuts grid power peaks by up to 80%, thereby lowering the carbon footprint and moving us one step closer to turning our vision for a sustainable observatory into a reality.
As noted in Figure 1, this system can easily be adapted to current and future telescopes. It is our hope that, once demonstrated in the field by the AtLAST team, others will follow this example and improve the sustainability of other astronomical facilities as well.
ACKNOWLEDGMENTS
This project has received funding from the European Union’s Horizon 2020 and Horizon Europe research and innovation programs under grant agreements No. 951815 (AtLAST) and No. 101188037 (AtLAST2).
REFERENCES
[1] Viole, I., Valenzuela-Venegas, G., Zeyringer, M., and Sartori, S., “A renewable power system for an off-grid sustainable telescope fueled by solar power, batteries and green hydrogen,” Energy 282, 128570 (2023).
[2] Mroczkowski, T., Gallardo, P. A., Timpe, M., Kiselev, A., Groh, M., Kaercher, H., Reichert, M., Cicone, C., Puddu, R., Dubois-dit-Bonclaude, P., Bok, D., Dahl, E., Macintosh, M., Dicker, S., Viole, I., Sartori, S., Valenzuela Venegas, G. A., Zeyringer, M., Niemack, M., Poppi, S., Olguin, R., Hatziminaoglou, E., De Breuck, C., Klaassen, P., Montenegro-Montes, F. M., and Zimmerer, T., “The conceptual design of the 50-meter Atacama Large Aperture Submillimeter Telescope (AtLAST),” A&A 694, A142 (Feb. 2025).
[3] Kiselev, A., Reichert, M., and Mroczkowski, T., “Energy recovery system for large telescopes,” in [Ground- based and Airborne Telescopes X], Marshall, H. K., Spyromilio, J., and Usuda, T., eds., Society of Photo- Optical Instrumentation Engineers (SPIE) Conference Series 13094, 130940E (Aug. 2024).
