Maui’s Sun-Telescope: how a 3.6-ton mirror stays cool enough to image the Sun
On Maui’s Haleakalā, the Daniel K. Inouye Solar Telescope uses a 3.6-ton Zerodur primary mirror and a seven-mile Dynalene coolant loop across 13 independent temperature zones; a heat-stop dumps about 95% of the incoming heat from a 12 kW beam, with nightly ice cooling to prevent overheating, enabling the sharpest solar images yet (roughly 20 km resolution) and revealing fine-scale solar features while funding questions loom over its operation.
