“How do you prevent contamination and what are the chances of finding a harmful microbe in the sample?”

after Earth return. We do not expect any microorganisms on Bennu and consider finding one a very unlikely event. The asteroid is too small and the radiation doses on its surface would kill any living organism in a very short time. We had to prove this as part of our Planetary Protection rating – which is Unrestricted Earth Return – meaning that we do not have to take any special precautions to avoid contaminating the Earth with extraterrestrial life. Instead, we hope to find organic molecules that may have led to the origin of life on Earth. We will focus on measuring the organic molecular inventory of the samples but don’t have any plans for biological assays.