  Despite their very low surface gravities, the surfaces of asteroids and
comets are covered by granular materials - regolith - that can range from a
fine dust to a gravel-like structure of varying depths. Understanding the
dynamics of granular materials is, therefore, vital for the interpretation of
the surface geology of these small bodies and is also critical for the design
and/or operations of any device planned to interact with their surfaces. We
present the first measurements of transient weakening of granular material
after shear reversal in microgravity as well as a summary of experimental
results recently published in other journals, which may have important
implications for small-body surfaces. Our results suggest that the force
contact network within a granular material may be weaker in microgravity,
although the influence of any change in the contact network is felt by the
granular material over much larger distances. This could mean that small body
surfaces are even more unstable than previously imagined. However, our results
also indicate that the consequences of, e.g., a meteorite impact or a
spacecraft landing, may be very different depending on the impact angle and
location, and depending on the prior history of the small body surface.
