Mars One envisions a colony of humans on the red planet, starting in 2025. Plenty of people think that is unrealistic, but the nonprofit is vigorously recruiting potential pioneers to go to mars, one-way, with no hope of coming back. Here’s the ambitious — some say too ambitious — timeline: February 13, 2015: About 50 men and 50 women learn they’ve made it to Round 3. Group challenges will test survival skills and math ability, but they’ll also reveal how candidates deal with adversity — and with each other.