Businessman Elon Musk says his company is building a powerful, reusable rocket and a spaceship that may travel to the planet Mars. The spacecraft would eventually be able to take as many as 100 people and their equipment to the red planet, he said. The entrepreneur announced his plan on Tuesday at the 67th International Astronautical Congress in Guadalajara, Mexico. Elon Musk is the founder of the American company SpaceX. It designs, manufactures and launches rockets and spacecraft. During his speech in Mexico, Musk did not talk about the September 1 explosion of SpaceX’s Falcon 9 rocket and the satellite it was carrying. But Musk did say he wants to establish a city on Mars. He said the planned city would be able to support itself -- complete with the ability to make iron, as well as pizzas. Musk wants human beings to be able to live on more than just one planet. And he said the best way to do that is to first colonize Mars.