What is SpaceX and why is Elon Musk working with Nasa?

SpaceX made history in 2020 when it teamed up with Nasa and sent two astronauts to the International Space Station and back again - the first time a private company has done this.

Now in April 2021, SpaceX Crew 2 is transporting four crew members to the ISS.

The company is headed up by the billionaire entrepreneur Elon Musk, but what is his main aim for the company?

Science correspondent Laura Foster, external takes a closer look.