A PASSION FOR SPACE
Dr Kerri Donaldson Hanna on asteroid missions.
We are in the midst of a new era of space exploration – the investigation of some of the smallest bodies in the Solar System: asteroids. These primitive bodies hold vital clues about the earliest times in our Solar System including the origin of volatileand organic-rich materials, the building blocks of life, as we know it. The exploration of asteroids allows us to better understand our beginnings here on Earth as well as the possibility of using their resources for taking humans to new places within our Solar System.
Missions to small bodies have become an international effort, with agencies from around the world actively developing and flying new spacecraft to these diverse planetary bodies. Currently two missions are underway. The Japanese Space Agency’s Hayabusa2 spacecraft has arrived at asteroid Ryugu and is busy selecting a sampling site and landing spots for its rovers, while NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) has begun its approach to asteroid Bennu. One of the main goals for both missions is to return samples to be studied using the best laboratories on Earth.
To pick out the best locations for collecting samples, each spacecraft will use instruments to perform reconnaissance of the asteroid’s surface, identifying regions that: (1) are safe for the spacecraft to sample the surface; (2) have plenty of regolith for collecting; and (3) are scientifically compelling. This will allow us to better map asteroid compositions across the Solar System and identify planetary bodies rich in volatiles and organics.
Fingerprinting asteroids
As a NASA-selected scientist on the OSIRIS-REx mission, the excitement for its rendezvous with Bennu in December is building. With each day, the spacecraft gets closer and closer and the view of the asteroid becomes larger and larger, allowing it to be studied in greater detail.
In preparation for the spacecraft’s arrival at Bennu, our research group at the University of Oxford has been making laboratory measurements of materials that Bennu is thought to be composed of. In particular, we’ve been using our bespoke vacuum chambers, which are capable of simulating the near surface conditions of asteroids, to measure the thermal infrared radiation (aka, heat) emitted from minerals, mineral mixtures, and meteorites. Different minerals and meteorites can be easily identified from one another because each has its own unique thermal infrared fingerprint (or spectrum). We’ve been building a library filled with thermal infrared spectra of as many minerals and meteorites as possible. Once the spacecraft begins mapping the surface of Bennu, we will begin comparing thermal infrared spectra of Bennu’s surface against spectra we measure in our laboratory at Oxford. In this way we will begin mapping Bennu’s surface composition, which will be used in picking a location for collecting a sample.
Over the next year, the OSIRIS-REx team will be busy poring over the latest images and spectral maps of Bennu’s surface, but it will be worth it in the end when the sample is collected and begins its journey back to Earth. We can’t wait to start the analysis of the real thing!