In the first episode of a new series this April, The Sky at Night met Ashley King, the only British scientist to take a first look at the asteroid sample brought back by NASA’s OSIRIS-REx mission
The formation of the Solar System was a little like making a cake. A set of ingredients – in this case, a vast cloud of interstellar gas and dust – were mixed together over 4.5 billion years to create the Sun, planets and moons that we see today. Planetary scientists like me aim to reconstruct that recipe, from the ingredients of the first solid materials in the protoplanetary disc, through to the evolution of habitable environments like the one we find on Earth.
I investigate the origin of the Solar System using asteroids, the rocky and metallic leftover building blocks of planets. I’m particularly interested in asteroids that formed in the cold, outer disc, as they retain the primitive composition of the Solar System and accreted complex ices that reacted with the rocky materials within their interiors. One such asteroid, 101955 Bennu, is now on a near-Earth orbit and was recently visited by NASA’s OSIRIS-REx mission. Bennu was selected as the mission target because it holds vital clues about our past, as its dark surface suggests a composition rich in hydrated minerals and carbon, including potentially organic molecules that may have been the precursors to life on Earth.
The primary aim of OSIRIS-REx was to collect a sample of Bennu and return it to Earth. I held my breath as the spacecraft made a daring sample grab using the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) in October 2020. Samples returned from known planetary bodies are a crucial tool in our efforts to understand the Solar System. Unlike most of the 70,000 or so meteorites in our collections, returned samples have geological context – we know which body they come from, and where and when they were collected. They’re also preserved in a pristine state, unmodified by the terrestrial environment. Our laboratories on Earth offer a level of analysis that often can’t be matched by any instrument on a spacecraft, while sophisticated curation enables samples to be analysed for many decades after the mission has ended.
The OSIRIS-REx spacecraft delivered its precious cargo to the Utah desert on 24 September 2023. The Sample
