2018 is not going to be the year that humans land on Mars. But, if millionaire space tourist Dennis Tito has his way, it could be the first year that humans visit Mars. Tito has formed a group called the Inspiration Mars Foundation, which is going to try to swing two people around Mars without stopping and then bring them back to Earth on a mission lasting 501 days.
From the press release:
This “Mission for America” will generate new knowledge, experience and momentum for the next great era of space exploration. It is intended to encourage all Americans to believe again, in doing the hard things that make our nation great, while inspiring youth through Science, Technology, Engineering and Mathematics (STEM) education and motivation.
Well, that sounds great, but let’s talk about the details. If we’re going to try and do something like this, 2018 is the year to make it happen due to an aligment of Earth and Mars that won’t occur again until 2031. There’s no landing on the table: the astronauts will be on a free-return trajectory, making a half-orbit of Mars and using the planet’s gravity to slingshot them back towards Earth. It’s the same basic technique that got Apollo 13 safely back home. A trajectory like this is the safest way to do it, although it means that the Mars close encounter will be relatively brief, likely just a few hours out of a mission that will last hundreds of days.