Here Robert Zubrin and Christopher McKay talk about terraforming Mars. Have your browser find "Moving Ammonia Asteroids" and it will take you to the relevant section about 3/4 down the page.

Zubrin and McKay talk about using a gravity assist. But using Saturn's gravity to toss down a 2.8 kilometer Centaur, not Neptune's gravity to toss down a 240 kilometer KBO. They figure .3 km/s would suffice to nudge an ice-teroid close enough to Saturn to throw it Mars-ward.

They also suggest vaporizing the asteroid's volatiles for the reaction mass. To accomplish this they propose a "quartet of 5000 MW nuclear thermal rocket engines". That's 20 giga-watts. The Palo Verde power plant is the largest nuclear power plant in the U.S. It is about 3.3 giga-watts.

So they're proposing sending the equivalent of 6 Palo Verde nuclear power plants out past Saturn. Not very plausible, in my opinion.

You seem to be talking about an object about a million times more massive than Zubrin and McKay's pebble. Let's say we could send it to Mars by nudging it near Neptune. For around .3 km/s, like Z & M's scheme. You'd need 20 million giga-watts. Sunlight's power density out among the KBOs is about 1/100 of what we enjoy. You would need a very large mirror.

Then what happens at impact? An object falling from 30 A.U. would strike Mars at about 10 km/s (at least). It'd have a kinetic energy of about 50 mega-joules per kilogram. I believe most of the cometary volatiles would escape Mars. The impact would also probably blast off all Mars' CO2 atmosphere above the tangent plane at impact.

Terraforming Mars via volatile rich asteroids pre-supposes we could send massive power sources to the asteroids and establish extensive onsite infra-structure.

If we had this ability, why not just use the asteroidal volatiles where they sit? Developing the small bodies would give us far more real estate and natural resources than the outer surface of Mars. I make this argument in more detail at Terraforming Mars vs Orbital Habs.

Here Robert Zubrin and Christopher McKay talk about terraforming Mars. Have your browser find "Moving Ammonia Asteroids" and it will take you to the relevant section about 3/4 down the page.

Zubrin and McKay talk about using a gravity assist. But using Saturn's gravity to toss down a 2.8 kilometer Centaur, not Neptune's gravity to toss down a 240 kilometer KBO. They figure .3 km/s would suffice to nudge an ice-teroid close enough to Saturn to throw it Mars-ward.

They also suggest vaporizing the asteroid's volatiles for the reaction mass. To accomplish this they propose a "quartet of 5000 MW nuclear thermal rocket engines". That's 20 giga-watts. The Palo Verde power plant is the largest nuclear power plant in the U.S. It is about 3.3 giga-watts.

So they're proposing sending the equivalent of 6 Palo Verde nuclear power plants out past Saturn. Not very plausible, in my opinion.

You seem to be talking about an object about a million times more massive than Zubrin and McKay's pebble. Let's say we could send it to Mars by nudging it near Neptune. For around .3 km/s, like Z & M's scheme. You'd need 20 million giga-watts. Sunlight's power density out among the KBOs is about 1/1000 of what we enjoy. You would need a very large mirror.

Then what happens at impact? An object falling from 30 A.U. would strike Mars at about 10 km/s (at least). It'd have a kinetic energy of about 50 mega-joules per kilogram. I believe most of the cometary volatiles would escape Mars. The impact would also probably blast off all Mars' CO2 atmosphere above the tangent plane at impact.

Terraforming Mars via volatile rich asteroids pre-supposes we could send massive power sources to the asteroids and establish extensive onsite infra-structure.

If we had this ability, why not just use the asteroidal volatiles where they sit? Developing the small bodies would give us far more real estate and natural resources than the outer surface of Mars. I make this argument in more detail at Terraforming Mars vs Orbital Habs.