Before planets can form, Gustafson said, dust grains must come together to form planetesimals, which then are pulled together by gravity to form planets. The formation of planets from planetesimals is relatively well understood. But the process by which planetesimals are formed from dust particles is less clear. To explain the possibilities scientists have developed various theories, some of which conflict. Fundamental to most theories is the role of the transfer of radiative energy in the formation process.
Energy can either cause gas to evaporate, or to condense, on dust particles.
That, in turn, influences whether colliding dust particles stick together. Gustafson and his co-investigators want to gather data that could be useful in creating new theoretical models that would help explain the process. Current theory doesn't do that well, positing a planetesimal formation process that would take more time than the few hundreds of millions of years in which planets are thought to form. Earth has not proved to be the ideal environment in which to test dust theories. To overcome the limits gravity places on the experiments, scientists have attempted to test dust reactions in micro-gravity situations by dropping instruments from specially designed tall towers, or by sending them aloft on rocket flights.