Free Astronomy Magazine January-February 2019

24 JANUARY-FEBRUARY 2019 SMALL BODIES Researchers expect to get information about the composition and initial conditions of our Solar System, and to understand if and how the primeval ma- terial brought to Earth by asteroids may have contributed to enrich- ing our planet with the organic com- pounds from which life was established. The in-depth study of Bennu (as well as that of Ryugu) has another remarkable goal – to understand the compactness of its making it the smallest body ever orbited by a probe. The scientific objectives of this first phase are to improve the estimates of the physical properties and the rotational period of Bennu, and to create a more precise model of its shape. By ex- amining the images and the data gath- ered with a suite of five scientific in- struments, mission technicians will be able to select the most suitable site for collecting the only sample of de- bris and regolith scheduled from the mission. This will happen in about a year, after which the collected sam- ple, weighing at least 60 grams, will be brought back to our planet, where it is expected to land in Utah in Septem- ber, 2023. The goals of the laboratory analysis of the ma- terial taken from Bennu are the same as those of the Hayabusa2 mission. A series of radar images of the asteroid Bennu, recorded in September 1999 by the Goldstone’s Deep Space Net- work antenna. Despite the poor resolution, the shape is already recognizable, as confirmed (below) by the OSIRIS-REx probe. [NASA/JPL- Caltech/Goddard/ University of Arizona]

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