Dr Kerri Donaldson Hanna discusses involvement in NASA's OSIRIS-REx mission on BBC Sky at Night podcast

Dr Kerri Donaldson HannaDr Kerri Donaldson Hanna, Postdoctoral Research Fellow in Physics at Christ Church and UK Space Agency Aurora Research Fellow, was recently interviewed on BBC Sky at Night magazine’s podcast, Radio Astronomy, where she spoke about her work as a participating scientist working on NASA’s OSIRIS-REx mission.

Dr Donaldson Hanna’s research focuses on understanding the formation and evolution of planetary crusts of airless bodies like the Moon, Mercury and asteroids. In the podcast, she discusses her involvement in the OSIRIS-REx mission to send a spacecraft to the asteroid Bennu and bring back samples to be analysed on Earth, to find out more about the makeup of asteroids and the process by which they may have been instrumental in giving Earth the ability to support life.

It is likely that asteroids are the building blocks of terrestrial planets such as Earth, Mars, Venus and Mercury, and they can tell us a lot about their history; according to Dr Donaldson Hanna, ‘understanding these small bodies tells us something about how our own Earth formed, and they also seem to contain the building blocks of life’. Some asteroids may come close to or impact Earth, so studying them and understanding their physical characteristics and chemical makeup allows us to begin to work out how to mitigate these impacts.

Dr Donaldson Hanna also discusses the criteria that were used when choosing which asteroid to target in the OSIRIS-REx mission, involving narrowing down 7000 near-earth objects to just 5 that had the necessary size, composition and orbit shape. Instruments on board the spacecraft heading to Bennu include cameras for mapping the surface, spectrometers that will tell scientists more about the geology of the surface and allow them to map its composition, and a laser altimeter, which will map its topography and surface structure. The spacecraft does not have a lander, and instead uses the ‘touch and go’ sampling method, whereby material is pulled into a sample head via a long arm.

These samples will eventually be returned to Earth, where a number of scientists, including several based in the UK, will work on analysing them. Dr Donaldson Hanna will be working with Dr Neil Bowles, also based in Oxford: ‘We’re mostly interested in trying to understand the surface composition and the thermophysical properties by looking at spectra that we’re going to get back from the spacecraft’. The mission is also groundbreaking in terms of the amount of sample that will be returned to Earth: ‘no other spacecraft has ever brought back this amount of sample before, so it’ll be the largest sample collection since the Apollo astronauts flew to the Moon and hand-collected sample at the lunar surface. So it’s pretty exciting and pretty amazing’.

Although the mission is already making important discoveries, there is still a long time to go before these samples will return. The spacecraft has been doing flybys of the poles and equator to understand its mass and shape, so that it could safely go into orbit around it, and until July 2020 will be carrying out compositional mapping in order to understand the surface composition and physical properties, and once there are maps of the surface a number of sampling sites will be selected. Sample will start making its way back to Earth in March 2021, arriving back in September 2023.

You can listen to the podcast online on the Sky at Night website.