The Mars 2020 Perseverance rover has explored the escarpment at the front of the western fan in Jezero crater, Mars, where it encountered a variety of rock units as in-place outcrops and as loose pieces of rock separated from outcrops, or “float” rocks. Comparing float rocks to in-place outcrops can provide key insights into the crater’s erosional history and the diversity of units in the Jezero watershed that the Perseverance rover cannot visit in-situ. Here, we used multispectral observations from Perseverance’s Mastcam-Z instrument to investigate the lithology and origin of float rocks found on the western Jezero fan front (sols 415-707). We identified four textural classes of float rocks (conglomerates, layered, massive, and light-toned) and investigated their physical characteristics, spectral properties, and distribution to interpret their source and constrain their mode of transport. We found that the conglomerate and layered float rocks are highly spectrally variable and altered with differing ferric and ferrous signatures, and they likely derived from local sedimentary outcrops in the western fan front. Massive float rocks are the least altered, exhibit ferrous signatures, and could have derived from local outcrop sources or more distal sources in the Jezero watershed. Massive float rocks separate into two subclasses: massive olivine and massive pyroxene, which likely derived from the regional olivine-carbonate-bearing watershed unit and the crustal Noachian basement unit respectively. The unique light-toned float rocks have variable hydration and low Fe-abundance, but there are no local outcrop equivalent of these rocks in the western Jezero fan or crater floor.

Africa is a continent with great assets for Astrophysics and Planetology (including astrobiology): skies unpolluted with anthropogenic light, meteorites and impact structures, and vast sedimentary-metamorphic-igneous records of early Earth’ geologic evolution. Aware of these assets, a community of scientists is involved in increasingly ambitious projects. Their original works notably highlight the African scientific heritage, alongside engagement in economic, cultural and societal development. One of the notable achievements of this group is the observation of three stellar occultations by asteroids in Senegal, in direct support of NASA missions of exploration of the Solar System. The first campaign was achieved in August 2018, in support of the flyby of Kuiper belt object Arrokoth by the New Horizons spacecraft. The second and third campaigns, in September 2020 and October 2021, in preparation for the upcoming flybys of Trojan asteroids Polymele and Orus by NASA’s Lucy mission, were led by Senegalese scientists, supported by a few European astronomers. Other notable achievements include fieldwork at potential or known impact structures (including search of tektites in Côte d’Ivoire), providing opportunities for student training and local education. Members of our group have also launched the first popular science magazine on astronomy (in French) (l’Astronomie Afrique). Last, founding the RISE 5A project (Astronomy and Astrophysics Arising Across Africa), with proposal intended to be resubmitted to the Horizon Europe program in 2022, together with some joint educational initiatives linking Egypt and Spain, will hopefully open new opportunities for staff and students exchanges between Europe and Africa. These achievements also impart an enduring engagement of the youth, while reinforcing the role of West African scientists in the scientific, cultural, and economic development of their countries and communities worldwide.