Microgravity Sci. Technol. (2010) 22:517–527 DOI 10.1007/s12217-010-9236-3 ORIGINAL ARTICLE Astrophysical Microgravity Experiments with Dust Particles Jürgen Blum Received: 28 December 2009 / Accepted: 23 August 2010 / Published online: 12 September 2010 © Springer Science+Business Media B.V. 2010 Abstract Dust particles play an important role in astro- physics. Experiments can help to describe their mutual interactions as well as their interactions with an am- bient gas flow or a field of electromagnetic radiation. In many cases, these experiments are not feasible in the laboratory, owing to the overwhelming effect of gravity. Then, only microgravity experiments can help to uncover the physics behind dust interactions. In this article, I will review the dust experiments, which we performed in the Bremen drop tower during the past years. These experiments have helped us to better un- derstand the role of solid particles in planet-forming re- gions, on the surfaces of small solar-system bodies, and in Saturn’s rings. Keywords Microgravity · Astrophysics · Dust Introduction Microgravity offers the unique opportunity to exper- imentally investigate the physical interactions of dust particles and agglomerates thereof in parameter re- gions unaccessible to laboratory experiments. Knowl- edge about the motion, collisions, the reaction to gas Electronic supplementary material The online version of this article (doi:10.1007/s12217-010-9236-3) contains supplementary material, which is available to authorized users. J. Blum (B ) Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany e-mail: j.blum@tu-bs.de flows, and the interaction with electromagnetic radia- tion of dust is of utmost importance for astrophysics, planetary science, and atmospheric research. In the past 15 years, we have performed more than 300 drop-tower flights to study the physics of astrophysical and plane- tary dust particles, which I will review in this article. I will start with some technological achievements, which allow the handling and manipulation of particulate systems under microgravity conditions, followed by an overview of the scientific results we obtained with the aid of drop-tower experiments. Technology Deagglomeration and Dispersion of Dust Cosmic dust particles are often (sub-)micrometer in size and are usually embedded in a tenuous gas. To study the motion and interaction of such small particles under realistic experimental collision, it is mandatory to – deagglomerate dust samples into their individual particulates, – disperse the dust particles as homogeneously as possible into a reservoir of rarefied gas, and – to achieve or sustain sufficiently high number den- sities (without leaving the parameter-space of inter- est) so that interaction timescales are so short that meaningful results can be obtained within the few seconds of free-fall duration. Based upon preliminary studies in the laboratory, we developed several methods for the deagglomeration and dispersion of micrometer-sized dust grains of arbi- trary composition into rarefied gas under microgravity