Hawarden, Timothy George

British-South African scientist Timothy (Tim) Hawarden was one of the most influential astronomers of the late twentieth and early twenty-first centuries, primarily due to his recognition of the critical importance for astronomy of radiative cooling of very large infrared (IR) space telescopes. The necessity to cool infrared astronomical optics and detectors to only a few degrees Kelvin was well known, but before Hawarden’s insight it was widely—and erroneously—thought to be possible only by surrounding the optical system with a massive toroidal tank of liquid cryogens, which perforce limited the mission lifetime and telescope aperture. In contrast, Hawarden’s radical alternative to instead use radiative (or passive) cooling in space is now taken for granted thanks to his work, supported, at first, by a small team of mainly European scientists ((Davies, The Space Review, August 21, 2006)). This concept led directly to the James Webb Space Telescope (JWST, (Gardner, Pub Astr Soc Pacific 135:068001, 2023)), which was launched on December 25, 2021, 1 day after what would have been Hawarden’s 78th birthday.