  The miniaturization of electronic and mechanical components has allowed for
an unprecedented downscaling of spacecraft size and mass. Today, spacecraft
with a mass between 1 to 10 grams, AttoSats, have been developed and operated
in space. Due to their small size, they introduce a new paradigm in spacecraft
design, relying on agile development, rapid iterations, and massive redundancy.
However, no systematic survey of the potential advantages and unique mission
concepts based on AttoSats exists. This paper explores the potential of
AttoSats for future space missions. First, we present the state of the art of
AttoSats. Next, we identify unique AttoSat characteristics and map them to
future mission capabilities. Finally, we go beyond AttoSats and explore how
smart dust and nano-scale spacecraft could allow for even smaller spacecraft in
the milligram range: zepto- and yocto spacecraft.
