Daily Kos writes, This was supposed to be a secret until this coming Wednesday, and it was secret, right up until someone spilled the beans almost a week early: Buzz is building about a planned 2018 private mission to Mars, which may launch the first humans toward the Red Planet. A nonprofit organization called the Inspiration Mars Foundation — which is led by millionaire Dennis Tito, the world's first space tourist — will hold a news conference on Feb. 27 to announce the 501-day roundtrip mission, which will aim for a January 2018 launch. Yes, there are many unresolved questions. But these people are not…