Why assume the Kryptonians can terraform anything when the film shows us evidence to the contrary?
Many detractors will propose Mars as a candidate without thinking through what they’re assuming. They clearly intuit that Mars is a better candidate than Jupiter or Pluto because they understand that technology has limitations. It isn’t magic that simply does whatever you wish it to. If Mars is a better candidate than Jupiter or Pluto based on the limitations of technology, why assume that Mars is even a candidate within the limits of an unknown alien technology? To the contrary, the film shows terraforming technology to be quite limited:
1. It’s difficult – If it was easy and if it garnered lasting results, after thousands of scout ships departed during the age of exploration, there would be living colonies or sister planets for Krypton to have evacuated to or for Zod to find during his 33 years of searching. The total failure rate suggests candidacy is quite limited.
2. Zod had limited tries – Jor-El’s Phantom Drive technology takes energy and didn’t solve Krypton’s resource crisis. If it did, they would have stopped mining Krypton’s core. That means that Zod has limited resources. He acknowledges as much, saying they were destined to starve before retrofitting the hyper-drive and explaining what they did have as scavenged. With limited resources and limited power, that means that Zod had a limited number of jumps with the Black Zero. Given how precious the World Engine was to his plans, why drag it into dangerous and unknown places with the Black Zero? Unless their limited power meant they couldn’t go backwards to fetch the World Engine after discovering a viable planet. For all we know, Zod had only one shot at using the World Engine before exhausting his Phantom Drive. If you have only one shot, don’t you use it on the best possible candidate?
3. The World Engine only modifies mass and atmosphere – These are the only things explicitly mentioned, so why assume World Engines can magically change anything about a planet? By proposing Mars, there’s already the assumption a World Engine can’t turn a gas giant solid, it can’t create liquid water from nothingness, it can’t directly modify a planet’s distance from its star, it’s orbit, or precession in relation to temperature, and it can’t give a planet a magnetosphere. Without a strong magnetosphere, any atmosphere created would simply be blown away by the solar winds. However, Mars has a frozen core incapable of generating a magnetosphere. We know World Engine’s can’t fix planetary cores otherwise the Kryptonians would have used World Engines to fix the instability of Krypton. This means that Mars is not a viable candidate for permanent terraforming. Certainly not an easy one or a better one than Earth.
4. There are no other candidates – Zod spent 33 years wandering as interstellar nomads. If terraforming was easy and candidates plentiful, why hasn’t Zod already terraformed a planet? Surely an entire planet shaped to Kryptonian needs and comfort is a far better staging point than a retrofitted prison ship. Isn’t it much more likely that Zod hadn’t found a viable candidate yet? Or, if he had, it didn’t meet his criteria and limitations as well as Earth did?
5. What about the Scout Ship and Genesis Chamber – Even if other viable candidates are out there, how does Zod get the Scout Ship to those planets? The Scout Ship was vital to Zod’s specific vision of Krypton which demanded genetically engineered eugenic perfection. The 18,000-year-old Scout Ship did not have a Phantom Drive and the journey which took Kal-El mere moments, took the Scout Ship 10-years to complete. The explorers underwent hibernation in order to survive the long journey. That to cross a mere 27.1 light years. The next nearest candidates, evaluated on only a few criteria we can observe from Earth, take years upon years to journey (even at that speed). Time that Zod lacks the patience and resources to take.
6. Scout Ships are scouts – The Scout Ships were equipped with a Genesis Chamber and a Growth Matrix, while World Engines stayed behind on the outposts until viable planets could be found. This means that the Scout Ships were intended to begin colonization even before the arrival of the World Engine (otherwise, why equip every Scout Ship with a Genesis Chamber?). That means that the Scout Ships were intended to land on planets that were baseline habitable to Kryptonians, even if they weren’t comfortable prior to the arrival of a World Engine. That suggests that a World Engine can only make an already habitable planet more comfortable, not turn an uninhabitable planet into Krypton.
This explains why, in part, the Kryptonian age of exploration failed. Although they had wondrous technology… faster than light travel, the ability to shape planets, etc…. their technology wasn’t enough, because it was limited and not magic. The sphere of what they could actually explore with approximately three-times the speed-of-light was limited and the planets they could actually terraform were limited.
When nothing shows us that a World Engine could terraform Mars into New Krypton, how reasonable is it to criticize choices based on that unfounded assumption? When everything shows us that terraforming is difficult and that Zod isn’t one for diplomacy or alternatives, is it reasonable to propose something contrary to the facts and the character we’re shown?