D/H ratios of different celestial bodies found in the solar system. The figure has been modified from A. E. Saal et al. (2013) with data from K. D. McKeegan et al. (2006) (Stardust) and K. Altwegg et al. (2015) (Rosetta). Other relevant values not shown include Rosetta’s measurement of 67P’s coma dust particles (J. Paquette et al. 2021). Also not shown are the additional cometary coma D/H measurements made since Rosetta, including those of 46P/Wirtanen (D. C. Lis et al. 2019), C/2014 Q2 (Lovejoy) (N. Biver et al. 2016; L. Paganini et al. 2017), and C/2012 F6 (Lemmon) (N. Biver et al. 2016), as well as a revised estimate for C/1996B2 Hyakutake (D. C. Lis et al. 2019).