Free Astronomy Magazine January-February 2021

14 JANUARY-FEBRUARY 2021 ASTRO PUBLISHING A n image of the sample-collection site ‘Nightingale’ with a silhou- ette of the OSIRIS-REx spacecraft overlaid for scale. [NASA, Goddard and University of Arizona] T he four TAGSAM approach sites selected after months of surface imaging and analysis. The sample was ultimately taken from Nightin- gale. [NASA/Goddard/U. of Arizona] the focus of an article in the Janu- ary-February 2019 issue. Bennu is a large near-Earth object (NEO) that crosses Earth’s orbit regularly. While most of the predicted orbits in the next few centuries do not bring both objects into close-enough proximity to worry about a collision, there are a few instances where the two may come into uncomfortably close contact. Furthermore, we can only predict with a certain confi- dence level how the gravitational influence of Earth (or even more distant bodies) on these approaches will affect the future orbits of the much smaller Bennu. Any other fac- tors that influence Bennu’s orbit are details that we need to understand to improve our models to know if, at some point, we need to start planning in advance to avert a planet-wide disaster. OSIRIS-REx has provided invaluable information about the composition and orbital dynamics of Bennu, which alone might be sufficient to improve our models and make pre- dictions for future close encounters. Well beyond the ability to measure the phenomenon in detail from Earth’s surface, we have now stud- ied another process occurring at Bennu that addresses yet another complicator to our prediction of the