To other worlds via the laboratory (Invited)

Planetary science is fun, largely by virtue of the wide range of disciplines and techniques it embraces. Progress relies not only on spacecraft observation and models, but also on laboratory work to provide reference data with which to interpret observations and to provide quantitative constraints on model parameters. An important distinction should be drawn between two classes of investigation. The most familiar, pursued by those who make laboratory studies the focus of their careers, is the construction of well-controlled experiments, typically to determine the functional dependence of some desired physical property upon one or two controlled parameters such as temperature, pressure or concentration. Another class of experiment is more exploratory - to 'see what happens'. This exercise often reveals that models may be based on entirely false assumptions. In some cases laboratory results also have value as persuasive tools in providing graphic support for unfamiliar properties or processes - the iconic image of 'flaming ice' makes the exotic notion of methane clathrate immediately accessible. This talk will review the role of laboratory work in planetary science and especially the outer solar system. A few of the author's personal forays into laboratory measurements will be discussed in the talk; These include the physical properties of dessicated icy loess in the US Army Permafrost tunnel in Alaska (as a Mars analog), the use of a domestic microwave oven to measure radar absorptivity (in particular of ammonia-rich water ice) and the generation of waves - and ice - on the surface of a liquid by wind with fluid and air parameters appropriate to Mars and Titan rather than Earth using the MARSWIT wind tunnel at NASA Ames.