It’s a dream for many children, but what does it actually take to become an astronaut? Science correspondent Hannah Devlin tells Ian Sample about her trip on a zero gravity flight with the European Space Agency (Esa). Back on solid ground she also got to speak to Rosemary Coogan, one of Esa’s newest recruits, about the rigorous process that led to her being chosen from more than 20,000 applicants, to become an astronaut, and what she hopes to achieve in her role