On September 22, RSES students contributed to Australian effort to monitor a robotic spacecraft, OSIRIS-REx. The spacecraft swung towards Earth and was directly overhead near midnight, swinging around the planet and blasting its thrusters to make the most of our gravity well. By sunrise it was shooting off into deep space again, on course for the near-Earth asteroid (NEA) Bennu. Throughout this so-called "gravity assist" OSIRIS-REx was tracked as part of an Australia-wide campaign led by Curtin University to confirm its reported trajectory. From the ANU, a team of PhD students from RSES, RSPE, and RSAA imaged it from a dark sky site near Nimmitabel, NSW.
Video images from the night can be seen here courtesy of Bryce Henson.
Bennu is a C-group asteroid, a carbonaceous, and volatile-rich group that in some cases may host pristine samples of the oldest objects in the Solar System. OSIRIS-REx will arrive at Bennu in August next year, and return a sample to Earth in 2023. Besides its scientific significance, the mission is also important for global security reasons. Bennu has an estimated 0.037% chance of collision with the Earth between the years 2175 and 2196. Were such an impact to occur, it would release kinetic energy equivalent to 1200 megatons of TNT (the largest nuclear bomb ever detonated released the equivalent of 50 megatons of TNT). An understanding of the asteroid’s structural integrity is essential for developing an impact mitigation strategy.