Young Star

1. in COSMIC • What is regolith? • The surfaces of asteroids are covered by “regolith”, or layers of loosely connected and fluffy fragmentary debris, produced (in particular) by impacts with other asteroids. Planetary and satellite surfaces are also covered by regolith. • How does its surface change with time? • The formation and evolution of regolith depends on the asteroid’s gravitational field and on the mechanical properties of its constituent particles. ICAPS will simulate such regolith by forming thick and fluffy dust layers (“dust cakes”) in microgravity. or model ICAPS • Measurements • light scattering • tensile strength • thermal conductivity • compressibility and influence of porosity • collisions by solid impactors and aggregates particle • Why is light scattering important in astronomy? • How do planets form? Protoplanetarynebula observation Dust is everywhere in our universe, both far away in the empty regions of space between the stars, and in our own solar system, in comets and on the surfaces of asteroids and planets. These tiny dust particles scatter stellar and solar light, and by studying the properties of this scattered light, astronomers establish the physical properties of the dust, in environments that are impossible for humans to visit. model 0-50 m/s YoungStar Gas Dust Protoplanet Gas 0-50 m/s ICAPS Credit: DIRBE Team, COBE, NASA Dust 0-50 m/s Credit: NASA Planets form in dense dust disks around new-born stars. When the protoplanets are still very little (smaller than about 1 km in size), dust agglomeration (sticking collisions) is believed to be the key process for planetary growth. • How do particles agglomerate? ICAPS will investigate the formation and evolution of small dust grains and agglo-merates under a variety of conditions. • What can we learn about comets from light scattering? Active comets, with their bright comae and elongated tails, have different light scattering properties. In the microgravity environment of the ISS, ICAPS will study the light-scattering properties of dust aggregates and icy particles, under a variety of cometary conditions. light source camera Credit: A. Dimai and D. Ghirardo, (Col Druscie Obs.), AAC