The ultimate floating hotel, a “cycler” to carry astronauts, and ultimately tourists, in orbit between Earth and Mars, is being worked on by US engineers. Cyclers are the brainchildren of Edwin “Buzz” Aldrin, one of the two Apollo astronauts to make the pioneering visit to the moon in 1969. These metal “hotels” would ferry people and materials across space between the two planets, aiding exploration and commercial opportunities on Mars. The first could be in business by 2018. “Some day people will be going to Mars on a regular basis,” said James Longuski, of Purdue University, Indiana, in the US. “Most people are convinced we are going to do this. The only question is when.”