Abstract: In systems and methods for freezing and subsequently thawing liquid samples containing biological components, a sample is fractioned into a very large number of small drops (10) having surface area to volume ratios of 1000 m-1 or greater. The drops are projected at a liquid cryogen (40) or at the solid surface of a highly thermally conducting metal cup or plate, where they rapidly freeze. The cold gas layer that develops above any cold surface is replaced with a dry gas stream (75). The environmental temperature experienced by the sample then abruptly changes from the warm ambient to the temperature of the cryogenic liquid or solid surface. To thaw drops with the highest warming rates, the frozen drops may be projected into warm liquids. The sample is projected with cold gas to the warm liquid, so that again there is an abrupt transition in the environmental temperature.