Elon Musk's massive Starship rocket is still only in the prototype phase, but the SpaceX founder is already planning a bigger version.
At over 387 feet (118 meters) in length, Starship will be bigger than the Saturn V rocket, which launched the first humans into space, as well as NASA's forthcoming Space Launch System.
A reduced-scale Starship prototype, , is currently in testing and successfully completed its first test launch last week.
However, Musk is already planning the next version of the spacecraft - which he claims will be twice as big.
Discussing the diameter of Starship with fans on Twitter , Musk said the the "next gen system" would probably be 18 metres wide - double the width of the current model.
Assuming it's kept at the same scale and its height is doubled as well, the future Starship model would tower over the launch pad at a height of 240 metres.
That's significantly taller than St Paul's Cathedral and around three quarters the height of the Eiffel Tower.
A spacecraft of this size would weigh nearly 90 million pounds (40 million kilograms), and need to over 100 Raptor engines just to get off the ground, according to Teslerati .
Musk's ambition should come as no surprise.
His vision of the future involves humans not only travelling to Mars but setting up colonies there - complete with governments, pizza restaurants and nightclubs.
Starship is a key part of this vision, with the giant rocket supposedly capable of ferrying up to 100 people at a time to the Red Planet.
During its test flight, the Starhopper prototype rose nearly 150 meters over the Texas coast before coming back down for a soft landing.
Musk has said his next move will be to hold a presentation to update the world on the design of Starship and any changes to his plans on September 28.
The final Starship will have a total of six or seven engines and be paired with a new SpaceX Super Heavy rocket (previously known as BFR or Big Falcon Rocket)
