Research

Sulfide minerals are common accessory minerals in samples returned from asteroids Itokawa and Ryugu and carbonaceous chondrites. Sulfides are formed by aqueous alteration events, and their chemical and microstructural properties can also be modified by surface processes on airless bodies. Initial analyses of samples from asteroid (101955) Bennu returned by NASA’s OSIRIS-REx mission showed the ubiquitous presence of sulfides.

Magnetite is a relevant component of asteroidal surfaces as this mineral phase has been identified in carbonaceous chondrites, on the surface of asteroid Bennu through remote sensing observations, and in samples returned from asteroid Ryugu. However, the effects of space weathering processes on magnetite have not been explored. To investigate how this mineral responds to space weathering, here we simulate micrometeoroid bombardment and solar wind irradiation for magnetite using pulsed laser and ion irradiation, respectively.

Transmission electron microscopy analyses of the polymineralic regolith particle RC-MD01-0025 show microstructural and microchemical characteristics indicative of space weathering on the surface of asteroid Itokawa. The depletion of sulfur and nickel was identified in space weathered rims on troilite and pentlandite minerals. This corresponds to the first report of nickel depletion in samples returned from asteroid Itokawa by the Hayabusa mission.

Several studies have suggested a significant water availability on ancient Mars that produced water bodies fed by surface runoff, precipitation or groundwater. Most of those studies have focused on the distribution and possible origin of those water bodies. However, the geochemistry of these lakes is and the implications for habitability is not well known. Columbus crater was previously proposed as a candidate groundwater-fed paleolake.