If we order NASA's exoplanet catalog by order of ascending distance from Earth, we'll see that the closest system to us is NOT Tau Ceti at 12 lightyears: it is Proxima Centauri at 4 lightyears from our solar system.
They are effectively taking Deimos out of the solar system, which could have unpredictable long-term effects on the orbits of everything else in the system, and moving it on a trip that will take three times longer than if they take it to Proxima Centauri!
You might argue "but VikingBoyBilly, Tau Ceti has a yellow G-type star like our sun, and Proxima Centauri's star is a pathetic M-type red dwarf." True true, but take a look at the exoplanets we discovered over the last decade (which the Martians of 2494 should have known about in even greater detail than we do now): The only planet in Tau Ceti's habitable zone is Tau Ceti f. So what's the problem? There's a rocky world in the habitable zone to colonize! Well, the problem is obvious when you notice the eccentricity of Tau Ceti f's orbit (which is 0.16) and it's orbital radius (1.334 from tau ceti) puts it outside of the habitable zone for more than half of the year, which is only about a third longer than an Earth year! It can't be colonized. Not without the assistance of artificial technology we can't even fathom. So the best thing to do would be to sit in the marathon at an ideal orbital eccentricity of 0.0... forever... so they'll just be living in a small, rogue moon.
Now take a gander at Proxima Centauri b! It's a rocky world capable of forming water that stays inside the habitable zone all year round! And it's a "Super-Earth" classification of planet with a radius just 1.08x wider than earth and a mass that's just 1.27x more than earth... so it would be like earth with about 25% more gravity. It's perfect! It's proximity to a red dwarf may mean a exposure to radiation from a dim star, but it's survivable and rife for terraforming.
How could the UESC be so stupid??????