Elon Musk schooled Donald Trump in rocket science after the president-elect awkwardly asked whether a rocket booster that crashed into the ocean could be re-used. The Republican joined the billionaire, who has been tapped to head up the newly formed Department of Government Efficiency, to watch a SpaceX launch in Texas. Mr Trump’s granddaughter, Kai Trump, posted their interactions in a vlog on her YouTube channel. Mr Musk appeared baffled when Mr Trump asked if the destroyed booster could be retrieved from the sea, before explaining the rockets SpaceX plans to launch in the future.