Instead of colonising Mars, or Titan or Venus ect we should be looking to colonise the closest exoplanet, Proxima Centauri b. The planet is likely tidally locked (so itll be an eye ball planet) 30% larger than earth. Despite retarded I FUCKING LOVE SCIENCE type articles claiming it wouldnt have an atmosphere, it probably does because it likely had a hydrogen or helium sacrificial envelope protecting its atmosphere AND more nitrogen due to its higher atmospheric gas retention. Not to mention constant replenishment from volcanic out gassing AND the constant addition of oxygen (as much as 30-40 bars) and hydrogen to the atmosphere from photolysed water vapor blowing off the hydrogen and eventually the oxygenhttps://www.aanda.org/articles/aa/pdf/2016/12/aa29576-16.pdf. As such a significant partial pressure of oxygen may have accumulated in the atmosphere that exists today having reach equilibrium, The atmosphere may potentially be breathable ! the atmosphere is also likely protected by a induced magnetic field due to its proximity to the star and may have its own magnetic field powered by convection currents . Surface temps on the day side more than habitable. If the atmosphere is thick enough ozone may exist at lower altitudes that can protect surface level habitations from the massive solar flares along with the radiation shielding of the atmosphere. Despite this protection, inhabitants will be engineered to express uv protecting astaxanthin and Scytonemin, iron scavenging proteins for ferritin damage to prevent free radicals, and humanised dna repair molecules from radiation extremotrophs. a beam core rocket or a fusion rocket could realistically get us to between 0.2c and 0.7 c so between 20 and 6 years each way, worst case scenario is we have to use project Orion and get there in 40 years. Vitrification of colonists will be used to endure these timeframes.