[m4rtink]

It only worked in the Expanse because they expertly choose a special trajectory that made the rocks hard to detect and some questionable (but plot necessary) "stealth coating".

By this point UN and MCR have been in cold war for 100+ years staring each other down with region killer nuke arsenals and an absurd amount of interceptors always ready. See than one time Mars actually fired a barrage - only like two warheads got through, only due to shitload of decoys and overall numbers.

A dumb rock would totally get vaporized without the plot armor in a safe distance.

[Ajakks]

Ok. The Expanse is a show/book - that doesn't actually portray any of this very well, but its very important to note - there are no satellites in orbit, with nukes or any kind of missiles - if you want to pretend they are, they are most definitely pointed at the earth.

I'd love to buy into that plot armor but there is too much to take seriously by S6. The reality is, the first time a colony decided to it was independent enough, to use an asteroid - they would pick one, or many, so as to to render earth uninhabitable, there is no doing what they did in the show - thats how you lose a war AFTER having already used a weapon of last resort.

Once Inoki or w/e his name decided to use an asteroid, and one hits, the ONLY choice open to Earth is an immediate unconditional surrender. The only correct choice for asteroid #2 is one that will end all life on the planet without any doubt.

What's her name? The President would have killed us all and attained nothing doing so.

[m4rtink]

I think given the technology that has been shown - a massive space and planetary infrastructure base, torpedoes with torch drives armed with nukes that would make Teller blush - I don't think you can actually use Dinosaur killer asteroid unnoticed.

That would be far too big to not be spotted by the many UN aligned sensor platforms all around Sol, well before it is actually on a collision course as changing the trajectory of something this massive could take a long time, not to mention for it to actually travel all the way to Earth on that trajectory.

I am sure that Belter Cheguevara was not the first one to get these ideas, so any major power not tracking most asteroid orbits in almost real time at this point would be stupid. The technology they demonstrated to have should easily allow that.

And by that point one of the many Ships UN has all around the system would just go there and shoot anyone working on the big rock to pieces. Possibly deploying tugs to change the trajectory to a safe one afterwards.

So I think they had to use rock small enough not to be easily tracked, that could be quickly accelerated + that special stealth coating from the Martians. Enough to kill a city and devastate a region but not much else.