Elon Musk, the co-founder of PayPal, a global e-commerce business, is planning to build a small city on planet Mars. However, there is a small catch - only 80,000 space explorers would be allowed to live on the red planet, and they must be vegetarians.

A month earlier, Mr Musk hinted the ticket prices for each Mars traveler would be an astounding $500,000. In justifying the price tag, Mr Musk was quoted as saying, "The ticket price needs to be low enough that most people in advanced countries, in their mid-forties or something like that, could put together enough money to make the trip."

Mr Musk, however, did not state if the payment could be made via PayPal.

He also did not explain why vegans are the preferred residents of Mars, but it may have to do with the planned futuristic settlement running on sustainable technology. He said the 80,000 targeted population is just enough since a small headcount would cause the gene and culture pool to dry up while too many people could risk a civil war.

Mr Musk told the Royal Aeronautical Society that his Mars dream has been for about a decade now.

"Then it seemed ridiculous because there were no rockets, no infrastructure and NASA was the only game in town - and it had no schedule for exploring Mars," The Hindu Business Line quoted Mr Musk.

To address the lack of rockets, he established SpaceX in 2002, for which he was awarded in November 2012 by the Royal Aeronautical Society a gold medal for his contribution to space exploration. SpaceX's Falcon 9 rocket delivers NASA cargo to the International Space Station.

"But with my work, and many others working in the private sector, the mission is coming closer to reality," he added.

The Mars-bound rocket would be powered by liquid oxygen and methane, and these are what the vegan residents would see based on images taken by Mars Curiosity.

People's curiosity of what life in Mars would be like was probably sparked by an American TV show title My Favorite Martian, first aired in 1963. Here is a video clip of that show.