Free Astronomy Magazine January-February 2019

SMALL BODIES 23 The OSIRIS-REx probe reached its goal, the asteroid Bennu, and en- tered its scientific phase. This mission, together with the Hayabusa2 probe around the asteroid Ryugu and other missions in an advanced phase of design, are expressions of the will to defend our planet from possible collisions with the rocky bodies that periodically cross Earth’s orbit. We are still far from a global coordination of these initiatives, but the first steps have moved us in the right direction. moon” Defense JANUARY-FEBRUARY 2019 O n December 3 rd , after traveling over two years and more than two billion kilometers, NASA’s OSIRIS-REx probe (Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer) finally reached the asteroid Bennu. This mission is almost a photocopy of the Japan- ese probe Hayabusa2 at the asteroid Ryugu and, incredibly, the two asteroids even ap- pear at first sight very similar to each other. After arriving near the asteroid, OSIRIS-REx started a series of approach maneuvers, which at the end of December ended with its insertion into operational orbit, just over 1 km above the Bennu surface. The probe then conducted a preliminary survey of the Bennu surface structures from a polar orbit. Bennu has a diameter of only 492 meters, I n the background, a depiction of the meteoroid 2018 LA, which disintegrated on June 6 th , 2018 in the atmosphere above Botswana just 4 days after its discovery. [NASA/ JPL-Caltech]