Asked by: Samuel Chaabane, Brighton and Hove
Gravity is easy to manipulate: it’s just a matter of moving masses around. The challenge lies in achieving anything useful by doing it, as gravity is incredibly feeble. Even so, NASA has succeeded many times, by waiting until planets are in specific locations before launching probes, and using the gravity of the planets to hurl the probes to precise locations.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.