Understanding that humans are uniquely adapted to the living conditions on Earth, are there planets that exist that closely imitate living conditions on Earth?
What are the living conditions like on each identified candidate planet?
Are there factors that prevent the spacecraft from entering orbit/landing on the planet?
What considerations must be taken into account when designing the spacecraft?
How do the conditions on each candidate planet support/challenge human life?
What areas of the planet are most suitable for colonization?