If we are terraforming a planet then why would you not want an earth-like planet? Unless there is plan to allow for the natural evolution of a martian ecosystem then I assume we would be wanting to reproduce an earth like ecology so earth plants/animals could eventually be native to Mars. Also if the plan is for martian environment to support life then "earthlike" would probably be the best.
Ryan is a biologist so I woukd be interested to hear how biologists could "figure out a proper biologigical model" - this sounds extremely naive to me. We barely understand earth ecosystems in their complexity - to then apply this to a foreign environment... Like is said I wuld be very interested to hear a biologist opinion on this.
With current economic depression - and future forecasts, I would argue most governments have to justify "why worry about that now?" As what would be the point in undertaking a massively longitdinal project without definitive success.
These two statements seem to contradict each other - the technology would need to be designed, produced and tested, then a comet located and redirected - I highly doubt 25 years is realistic. Also with regards to Ammonia Asteroids:
"While attractive in a number of respects, the feasibility of the asteroidal impact concept is uncertain because of the lack of data on outer solar system ammonia objects. Moreover, if Td is greater than 20 K, a sustained greenhousing effort will be required. as the characteristic lifetime of an ammonia molecule on Mars is likely to be less than a century, this means that even after the temperature is raised, ammonia objects would need to continue to be imported to Mars, albeit at a reduced rate. As each object will hit Mars with an energy yield equal to about 70,000 1 megaton hydrogen bombs, the continuation of such a program may be incompatible with the objective of making Mars suitable for human settlement."
Nikitin I do agree with you and I think in the next thousand years then these sorts of projects become more and more technically
feasible. Note I bolded technical as these are not the only limiting factors. Increasingly cost may be the main concern for a long term project of this nature - it may be that commercial reasons push terraformation projects.