People left to colonize North America because they were trying to get away from something, usually tyrannical rule. These are scientists who would be voluntarily accepting a death sentence that might happen in 5 years, or maybe 2, or maybe right after launch. Either way, they would be leaving for the purpose of scientific advancement whereas colonists were leaving to make a better life for themselves and their families.
Also, what happens when they get there, or are enroute, and decide they want to come home? What a public relations nightmare.