Biotechnology leader Noubar Afeyan PhD ’87 urged the MIT Class of 2024 to “accept impossible missions” for the betterment of the world, in a rousing keynote speech at the OneMIT Commencement ceremony this afternoon.Afeyan is chair and co-founder of the biotechnology firm Moderna, whose groundbreaking Covid-19 vaccine has been distributed to billions of people in over 70 countries. In his remarks, Afeyan briefly discussed Moderna’s rapid development of the vaccine but focused the majority of his thoughts on this year’s graduating class — while using the “Mission: Impossible” television show…